N6CC: Recent Episodes
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Updated 4/29/2025: Members of the West Coast Military Radio Collectors Group deployed a Communications Forward Operating Base at MVCC Camp Plymouth for the April 2025 event.
The intent was to provide the Military Vehicle Collectors of California club with tactical, theater and strategic communications as necessary. Enabling the MVCC to Move, Shoot AND Communicate! The After Action Report follows:
The MVCC is a non-profit organization of collectors and historians interested in encouraging the acquisition, restoration, preservation, and public display of historic military vehicles and related militaria. It is the largest regional military vehicle collector organization in the U.S. The MRCG is similar – except military radios are the vehicle.
Lots of sun and a warm breeze made for a nice 3-day operation under the ParaHootch. The Battalion Comm Center had lots of visitors and we reconnected with many friends.
This OP entailed issuing a FRAG Order to the troops to set up a Forward Operating Base (FOB) in the Amador County (CA) Fairgrounds. The purpose was to demonstrate the use of military radio gear from WWII through Vietnam and the Cold War eras and have some radio fun. Primary authorized freqs were 3.885, 7.050 and 51.00 mc in Ham radio service.
A 1960’s era long-range high frequency AN/TRC-77 morse code set was used for primary comms. We made contacts in NORCAL and SOCAL locations with it although daytime propagation on 7050 was weak (high D-Layer absorption). We also received good signal reports from Oregon and Utah; low power CW works in-theater!
The 10-watt AN/TRC-77 HF CW Manpack set is a very capable field radio system and my go-to camping set at places like Camp Plymouth. The receiver sips battery power. The internal gel cell batteries will power the receiver continuously, 24/7, for over a month. Ideal for monitoring the Alert Net from an FOB.
TRC-77 comms included a SITREP from one of our members who was operating CW while mobile. He was en route at the time running a Transworld RF3200E suitcase set sitting on the front seat of his truck.
On site equipment also included a “Cold War” PRC-174 and a Yugoslavian RU-20 HF manpack sets plus a 70’s British clandestine/diplomatic service MK-123 morse code set.
(There is a VERY interesting story about how a MK-123 set hidden off-site was used to alert the UK that Iranian “students” had seized, looted and burned the UK Embassy in Tehran in 1978. The battery-powered MK-123 was used to send the alert after power and communications lines had been cut. That was done on an emergency frequency by a CW message, encrypted via a One Time Pad. It was received by the Australian Government station in Darwin in the Northern Territory of Australia. That’s 6144 miles if you’re counting. Twenty watts of CW does the job.)
You can learn about some history at the Forward Operating Base. Here is one in operation:
Below is the Collins-designed RU-20, a set built in Yugoslavia under license. Also known as the PRC-515, it provides 20 watts, 2-30 mc AM, CW and USB/LSB in a manpack. We were monitoring the Pacific Maritime Mobile Service Net on 14,300 kc in case any open ocean sailors needed our assistance.
The HF wire antenna installation at our Forward Operating Base was simple. It used a DIY PVC dipole mount with Balun, held up by 15′ of AB-85 mast sections which also held up the T-10 parachute. On the right freq at the right time of day it’s a very good NVIS system for regional contacts, our goal.
Additionally, we ran a VHF FM tactical Net which included a Vietnam era PRC-77, PRC-6, VRC-46 and a PRT-4/PRR-9 “Helmet” set on the Net throughout the event areas. We also had a Racal TRA-967 VHF FM set that was formerly operated by Saddam’s army in Kuwait. These are all interoperable FM sets.
We also had 6+ WWII BC-611 “Handy Talkie” portable sets on the Net simultaneously among the various venue patrols. Was this the largest collection of these WWII radios in Net operation since the defense of the Pusan Perimeter in Korea? They still do the job. For a 1940 design they are not perfect (through the lens of 2025, or even 1945) but vastly better than hand signals at night or sending runners during a firefight, the previous alternative.
Below: Your basic candid action photo. “Checkmate King 2 this is White Rook, Over”. You remember. The guy on the right could not understand why his PRT-4/PRR-9 FM Helmet Set was not interoperable! Can you hear me now? LOL
This deployment was designed to be simple, portable and low-profile. As a result we only used battery-powered field sets as this site had no power, water or any other utilities. The TRC-77 battery was solar-charged but aside from that we ran for 3 days un-resupplied. Except for some great BBQ provided by the Ione CA VFW Post 8254!
NO commercial/civilian/Ham radio equipment was involved at this site, as it should be at an event like this.
Other MVCC members had bolted their military vehicles to their cool, operational military radios too! Not surprising, many military vehicle owners are also Hams to add that dimension to their joint hobbies. Plus camping! We had fun passing Swap Meet SITREPS around the event which even included Russian, Spanish and German operators (ahem!) who were heard this close to The Front Lines.
We had hoped to run an east coast/west coast comm check with military radios on each end. A friend with an M-151 MUTT/GRC-106/Whip back east plus a Humvee and 150 watt PRC-138/Whip set on the west coast end. This was hoped for Saturday afternoon on 18145 kc when there was a chance for useful propagation but well after our FOB had to shut down. Alas, our end then had to abort due to MVCC club duties, the annual business meeting and dinner conflicting. Rats! We will try again when an east coast MV rally is happening. Hopefully some other MRCG members tried from their locations Saturday.
Some of the Usual Suspects are seen below with the portable sets monitoring the Nets. Operators included these folks plus several other participants scattered around the event.
The MRCG group includes experts in researching, repairing, restoring and operating this type of military comm equipment. They can often be heard using this historic gear on weekly west coast military radio nets.
For you Military Vehicle fans these kind of Ops do require an FCC-issued Amateur Radio License to transmit with this equipment these days. A “No Code” license can be earned by passing a written test administered by your local radio club under the auspices of the American Radio Relay League. A 1-day class can do it. Easy, get some of those rigs going on your MV’s. Those mobile whip antennas are not just for MVCC flags ya know!
Got Comms? Yes. Mission Accomplished
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Some Links:
Interested in getting a license? Visit https://www.arrl.org/licensing-education-training
For more information on the AN/TRC-77 radio take a look: https://www.n6cc.com/trc-77-hf-cw-transceiver/
Check out the MVCC website: http://www.mvccnews.net/
Or the MRCG website: https://www.mrcgwest.com/
Check out our similar FOB from Winter Field Day 2025: https://www.n6cc.com/winter-field-day-2025/
The post A Communications Forward Operating Base appeared first on N6CC.
In an effort to encourage grid-down emergency communications exercises with rugged, reliable equipment the following After Action Report is posted..
The above is KGO-AM San Francisco after the 1989 Loma Prieta earthquake. Done.
A friend and I set up 2 off-grid stations on Brannan Island in the Sacramento River Delta this past weekend. This is an Island in the river system; it is also a Park and we were set up on its high point (23′) above ! sea level. So we were informally operating an Island/Park and Summit on the air: IOTA, POTA, SOTA simultaneously.
Here is an early morning shot of my very hasty but portable setup on the island chatting with Andy in Coalinga via morse code:
Winter Field Day is a National emergency communications preparedness operating event and not a contest. Our goal was to exercise our equipment and our “Go Kits” from the field. To this end we contacted and chatted with our like-minded friends on HF CW (Morse Code), SSB and AM voice modes. We did not claim any contact points or even keep a log of contacts.
The American Radio Relay League sponsors “Field Day” every June with the same goals and upwards of 30,000 hams in North America participate. Winter Field Day has the same purpose with the added challenge of cold weather and more austere conditions. Stuff can happen at any time.
The winter weather in central California was mild with highs of around 50 and lows at night hitting 32 F. My buddy brought his camper trailer, I snoozed in the Bronco Tailgate Motel. It’s my dedicated camping truck which is otherwise pretty comfy. We were here for 3 days, 26, 27 and 28 January 2025. This included Sunday of the Winter Field Day Operating Period. Below is the simple site overview:
We operated 2 separate stations on site, both included PRC-174 manpack HF sets. These covered 2-30 mc providing 20 watts of CW and SSB plus 5 watts of DSB AM. We also had a PRC-77 and a Racal TRA-967 low band VHF FM set for local ops on 6 meters. We were both running low (20′), horizontal HF dipoles on 40, 60 and 75/80 meters. We are both primarily Morse Code operators although we used AM and SSB voice as well.
My setup also included a 1950-60’s Special Forces long range, crystal controlled AN/GRC-109 CW set. This set can be powered by a hand-cranked DC generator but I chose my DIY 12 volt power supply this time. The transmitter is tilted up in my transit case to access the built-in (pretty good) CW key; the receiver had a separate long wire antenna.
This rugged set was designed to be cached underground if necessary or even under 16′ of water until needed. It was a mainstay for Reconnaissance troops in Vietnam, Europe and elsewhere. Bomb proof (but heavy), it provides dependable comms and is ideal for my purposes.
I also had an SSB/CW PRC-47, AM/CW GRC-9 and an FM VRC-7 (RT-70) installed in the Bronco for mobile ops.
My buddy is a Marine Corps veteran, I am a retired Navy veteran. Both of us and our friends in the West Coast Military Radio Collectors Group have a long interest in military communications and military radios: hence the “unusual” load out.
Consequently the friends that we contacted on the Nets were running a Korean War GRC-9 on AM, a WWII British Wireless Set 19 HP, a Cold War Russian R-353 “spy” set, a Vietnam era TRC-77 CW set and a 1980’s Yugoslavian PRC-515. The PRC-174’s were a Hughes Aircraft design manufactured in Israel. A very international gathering.
No commercial radio equipment was used in any contacts and we made multiple contacts each with these other stations over 30, 37 and 155 mile paths via ionospheric NVIS. No commercial power or any other infrastructure was involved at this site.
The worst CW report we received was RST 569, very good. However CW (and some 60 meter Voice) comms were often being “jammed” by the incessant, non-stop digital drone of %&*@! computers slowly texting “599” to each other tying up the 7040/7050 kc CW freqs. Sorry, Rant over. Improvise, adapt, overcome.
While working Andy on his Russian spy set I donned my Russian Navy Ushanka hat as a symbolic but warm accessory. За тебе товарищ!
My setup was solar powered via a 12 volt garden tractor battery recharged by a 20 watt solar panel. I also had that smaller panel to charge the cell phone if needed (the phone wasn’t used). A small DC-DC converter generated 24 volts from 12 volts for the PRC-174. The other station on site used 2 deep cycle 12 volt marine batteries in series for his station. If my fishing skills were not laughable we could operate here indefinitely!
The OSHA-Approved, hasty power system. It easily kept up with the demand:
Speaking of cold, woolen trigger finger mittens are called for and especially good for operating CW with the J-45 Knee Key driving the PRC-174:
Night time is the right time: The Aether never sleeps.
As part of my contingency field kit I also sent and received some HF Winlink radio-internet-radio EMail messages. This was utilizing a simple PC notebook driving a Signalink USB interface to the PRC-174 handset connector for transmit and receive.
EMail messages were sent and received well; this is a very handy off-grid capability if commercial power, cable, WiFi, internet or cell connectivity is compromised locally or regionally. My messages were handled by the automated gateway station W7DEM in Reno NV. It was an easy 141 mile HF radio shot. This is on 7102 kc, up into the otherwise rarely utilized 7100-7125 kc sub band.
But at some point you have to EAT! (It’s a rule…) Roughing It.
Coffee ‘N Code: Life is good – We got this!
Some Techno-Details: Below is a report from the Reverse Beacon Network of test messages received that I had sent in CW during the exercise. These 10-20 watt portable sets get out quite well on 40 meters. Several spots were in excess of 500 miles but I was not trying for long distances. They can go much further on the higher bands if needed. (I have worked over 30 states and into Europe and Japan with the GRC-109 in the past.)
| ● spotter | ● spotted | distance mi | freq | mode | type | snr | speed | time | seen | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | N6TV | N6CC | 39 mi | 7050.0 | CW | CQ | 10 dB | 16 wpm | 1744z 28 Jan | 2 days ago | | K2PO/7 | N6CC | 527 mi | 7050.0 | CW | CQ | 17 dB | 16 wpm | 1744z 28 Jan | 2 days ago | | K2PO/7 | N6CC | 527 mi | 7050.0 | CW | CQ | 16 dB | 16 wpm | 1751z 27 Jan | 3 days ago | | W6YX | N6CC | 29 mi | 7050.3 | CW | CQ | 15 dB | 16 wpm | 1729z 27 Jan | 3 days ago | | K2PO/7 | N6CC | 527 mi | 7050.4 | CW | CQ | 18 dB | 15 wpm | 1728z 27 Jan | 3 days ago | | K2PO/7 | N6CC | 527 mi | 7050.0 | CW | CQ | 20 dB | 16 wpm | 1659z 27 Jan | 3 days ago | | W6YX | N6CC | 29 mi | 7050.0 | CW | CQ | 17 dB | 16 wpm | 1659z 27 Jan | 3 days ago | | N6TV | N6CC | 39 mi | 7050.0 | CW | CQ | 12 dB | 15 wpm | 1659z 27 Jan | 3 days ago | | N6TV | N6CC | 39 mi | 7050.3 | CW | CQ | 14 dB | 17 wpm | 0012z 27 Jan | 4 days ago | | WA7LNW | N6CC | 468 mi | 7050.4 | CW | CQ | 12 dB | 14 wpm | 0007z 27 Jan | 4 days ago |
I am a long time member of the Contra Costa County Sheriff’s Communications Unit attached to the Emergency Services Support Unit. This is great training and preparation for “When all else fails”.
Of course this was a fun “ham radio” oriented exercise but the principles, procedures, equipment and overall utility of grid-down communications is universally applicable.
Got Comms? Yes. Mission accomplished.
BT
NNNN
Certainly not a “military radio” but a radio nonetheless. I bought this Lafayette HE-90 CB transceiver in 1964. After the Heathkit CR-1 Crystal Radio, it started my long road into learning electronics while in High School and beyond.
Next to Ham Radio, CB was THE vehicle for “Social Networking” for many in those days; well before “Smokey and the Bandit” started the national CB radio craze 13 years later. Internet? What’s that? Cell phones? were sometimes installed in Jail cells to call your Lawyer.
Many of my buddies and cousins had CB’s in the mid 1960’s and it was a lot of fun. Plenty of clandestine capers were coordinated on channel 13.
With the 1958 creation of 27 mc Citizens Band radio, the FCC required a CB Class D license. However back then we were all under 18 and ineligible so we convinced our parents to obtain the required license. What were THEY thinking? haha
Legit call signs were routinely in use back then – it was The Law and the FCC was to be feared! Unlike the free for all that followed a few years later on CB after the FCC gave up.
I bought this one at the Lafayette Radio store in Syosset NY for $89.95; that was a LOT of paper-route work for Newsday and odd jobs back then. That’s $913 in 2024 dollars!
This radio was made in Japan by Trio Corporation, later to be renamed “Kenwood”, you may have heard of them. Branded by Lafayette, the HE-90 and dozens of their other CB radios kept Lafayette in business for many years. These and their myriad competitors equipped the nation’s truckers, farmers, ranchers, hunters and families as it was intended. Plus Good Buddies and curious kids.
Playing with this radio taught me a LOT about radio communications, antennas and electronics in general. This much abused transceiver was modified (ham-mered) by me to include an RF gain control, Noise Limiter disable switch and a nice red incandescent pilot light (LED’s had not yet been invented). And a VFO jack. The S Meter was our Video Game.
We all did a lot of experimentation with antennas, microphones and audio processing (clippers, compressors) to “improve” the transmitted signals. I used the Argonne AR-54 crystal desk mic a lot. Most of us considered it superior sounding to the classic, expensive D-104 Lollipop mic. Universally known as “The Green Hornet microphone”, at $3.95 it was a deal! See below.
Another modification was to change the 5-pin Amphenol microphone jack on the front panel and replace it with a 1/4 inch 3 circuit stereo type and a T/R relay for PTT. That made it compatible with the other microphone connectors I had available.
I also did that because I needed that 5-pin female connector to restore my 1950’s CIA RS-6 spy radio system which amazingly used the same connector between the transmitter, receiver and power supply. Improvise, Adapt, Overcome. But that’s another story.
But the fun didn’t stop there. I also had these two Lafayette CB walkie talkies, Bicycle Mobile. The 100 milliwatt HA-60 and later the GT-50 which was a 2 channel set with 500 milliwatts output, a squelch circuit and a battery status meter. They were a solution looking for a problem. Lots of sneaking around town/school ensued. Night Ops…
Like the night Artie climbed up the massive water tower in town to see how far his walkie talkie could reach across flat Long Island. Fun, until we illuminated him with a huge spotlight – TURN THAT OFF!!! That experiment ended quickly…
The 500 milliwatts output required a license to operate (imagine the bedlam one could create with one of these). The HA-60 could be operated “unlicensed”.
After seeing a Korean War PRC-6 “Handy Talkie” I had to paint the HA-60 with OD spray paint (very tacticool you know) but the walkie talkie’s were both handy and fun. I often used these while fishing from a rowboat on Shinnecock Bay to talk to my parents a few miles away back at the “base”. All over salt water, they worked great.
Olive Drab radio-equipped small boat operations conducting clandestine beach landings came later in life, but I digress.
I soon earned my Novice Ham radio license in 1966 and quickly upgraded to General and Extra Class while still in High School. Those higher licenses enabled me to use the HE-90 on the 10 meter ham band, specifically for participation in the Long Island RACES (Radio Amateur Civil Emergency Service) AM radio network. (“FM” had yet to become widespread on 2 meters for these sorts of nets and general Ham use.)
FCC Regs required anyone “tweaking” a CB radio transmitter for use on the CB channels to have a First Class Radiotelephone Operators license. So off to the New York City Federal Building to take and pass that license exam. Check. But then, for me, it was Adios CB…
Ten Meters Ops: A hack my cousin showed me was to take the channel 9 receive crystal and insert it into the transmitter channel socket, realign and presto: operation on 28.715 mc for the 28.720 mc Net. Close enough. (At this point, and to me, a “Wide Receiver” is indicative of the primary-secondary IF transformer coupling, not some overpaid NFL football catcher. HaHa)
The radio has an IF of 1650 kc so the “high side injection” receive crystal operated the transmitter on that 10 meter frequency. 27.065 + 1.650 = 28.715. Neat! CB rigs modified for 10 meters were common back then.
The red Dymo label above the tuning dial and the gray tape over the word “Citizens” (Band) on the front panel completed the conversion to 10 meters Ham ops!
I then figured out how to drive the transmitter with the VFO section of a modified BC-459 Command Set transmitter. I adjusted its VFO to provide a signal near 9.5 mc which was then tripled in the HE-90 to enable VFO operation on 10 meters.
The HE-90 could even work CW by inserting a key into the PA cathode current monitoring jack on the rear panel.
With my 4 element Cush Craft Yagi and even the 5/8 wavelength Colinear II ground plane antenna I was able to work some AM stations in Europe, Africa and many all over the US and Caribbean with this lashup. Ten meters was pretty hot back during solar cycle #20.
At one point I even tried to inject the 28 mc signal into the BC-459 transmitter PA stage using the 1625’s as a “Linear” amplifier. This was before I understood the difference between Class C and Class A amplifier biasing. HaHa! That experiment thankfully ended quickly but I then learned about vacuum tube biasing and linearity (and filtering etc…).
With its external vibrator pack, the HE-90 spent some time installed in the family 1962 Chevy Nova and then many more years installed in my 1971 Ford Bronco, working on 10 meters. The 102″ whip antenna was the way to go but you rarely see them any more.
All this was a lot of fun for this kid and it quickly became a life-long interest in communications and electronics, both in further education, employment and operationally in the US Navy. The Magic of radio captured my curiosity; I wonder what captivates kids these days to propel them into the future.
The establishment of Amateur Radio in the US 100+ years ago had a probably-unintended consequence. It produced many thousands of electronics-savvy people just in time for WWII. Those Hams were quickly put to work teaching electronics, radio communications and the all-important Morse Code skills essential for the war effort. Likewise, how many of the later “CB-ers” also moved on and into today’s wireless and electronics technologies with those similar roots.
Epilog: I still have the HE-90 and it still sounds great with its Heising plate modulation. The receiver is “Hi Fi” with its wide IF bandwidth and it is very sensitive with its 6DS4 Nuvistor RF amplifier stage. It works great with the AS-1729 military vehicle whip antenna installed at the base station. But listening to today’s CB band is quite “entertaining”.
With the great “skip” propagation on the upper HF bands in 2024, signals from all over arrive here. “Ol’ Gator” in the Loozianna Swamp talking with “The Big Dingo” in Australia on Channel 18. Lots of pretty good music and endless “characters” abound. CB Lingo is alive and well, well.
No qualms about describing your Kenwood TS-990 transceiver driving your Ameritron Kilowatt amplifier either. “Which sounds better – this pair of 811’s or……click, this 4-400”.
Plenty of Viking Valiant’s, DX-100’s and Yaesu FT-101’s out there, and that’s just on AM! Some of these classic Ham rigs included 11 meters as original since 11 meters had been a Ham band before 1957. (Hams have not forgotten this!) Many of the first CB-ers were hams as a result.
The SSB “Freebanders” between Channel 40 and 28+ mc blast in. But some offer good advice:
“It’s not the Poooower, it’s what’s on the Tooooower” good buddy! (with max Echo Effect.)
“You be talkin’ to Da Man most IN Demand on Da Band”! DJ Wanna Be’s are everywhere.
Long ago and far away…… YOU remember….
ARRL Field Day 2024: In an effort to encourage more off-grid, portable field radio operation and exercises the following After Action Report is posted:
I used some of my usual equipment from Mt Diablo State Park this year as in the recent past: “aPOTA”. “A Park On The Air” although very unofficial and unannounced. I operated Class 1BEB (1 transmitter at a time, battery operated, in the East Bay Section.) But I don’t “do” contests, or even keep a contacts log when in the field.
Battery powered, man-portable military radio gear makes this a simple (and effective) off grid and emergency communications exercise with like-minded people. As before, I also ran the PRC-174 for some HF Winlink test messages to/from the Internet using the laptop PC and a Signalink radio interface.
That messaging was via an automated HF Radio/Internet interface gateway station in Reno NV, a 163 mile HF shot. This is very handy Internet EMail connectivity from The Bush. EMail your buddy: “I’m here, Get on the air!”
Included was the British Racal TRA-967/3 man pack transceiver running on 6 meters FM, 52.525 mc. The Picnic Table TOC – Field Day BBQ not included.
I made a bunch of CW contacts (and a few SSB voice) on HF using the PRC-174 20 watt man pack set as mounted on the ALICE Pack frame. Seen below with the whip antenna later tilted downward to enhance the NVIS effect for regional contacts.
I had good results inside central California on 40 meters with the antenna deployed like this (also running a quarter wave ground wire). Propagation was otherwise very good. The tilted whip won’t out perform a low horizontal dipole, but this is easy and worked under today’s conditions.
Eg: Had a nice chat with Mike at Maritime Radio Historical Society station K6KPH in the Marin headlands, a 42 mile, midday NVIS shot on 7050 kc CW.
The AN/PRC-127ef handy talkie was along for monitoring the local simplex and repeaters on 2 meters. This is the 3rd generation of the PRC-127; the “ef” model is made by EF Johnson and is keypad programmable. These were designed for use by Combat Support units and not technically “tactical” combat equipment. They can include P-25 digital and DES encryption as options as needed. A rugged, semi-COTS radio. (EFJohnson 5117)
I also had the PRC-47 HF transceiver as normally mounted in the Bronco. It can be easily dismounted for field-portable ops. It provides 20/100 watts of HF CW, RATT/RTTY or SSB, 2 to 12 mc. I have 2 modulator modules so I can switch between them for USB or LSB operation; just plug in the desired sideband. A military USB net or Field Day favorite. Fixed, portable or mobile.
The little fold-down operator table is handy when needed. With the patch panel I can connect the PRC-47 or GRC-9 to any number of antenna systems including the MP-57/MS-49/52 mobile whip, external dipoles or other wire antennas when fixed-portable.
On a related note: This Op was also a shakedown cruise for the ChiCom “MGGi” 12 volt-to-24 volt converter I bought via Amazon. See below. I would have preferred the US Mil. EMCU-116 converter to power the 24 volt PRC-47 from the vehicle 12 volt system but this was readily available and cheap at $36. I just installed it in the truck to evaluate it to power that radio. The efficiency, regulation and ripple “specs” looked good but Caveat Emptor.
This one is rated to deliver 20 amps, 480 watts; more than enough although its output is fixed at 24.0 Volts. A few more volts would be better but it does the job with the PRC-47 in high power mode just fine. So far it has proven to be RFI-quiet while in operation, always a concern with SMPS power supplies.
Note to self: The converter draws an idle current of 30 ma @ 12 volts with no 24 V load. It pulls 1.5 amps@ 12 volts to power the PRC-47 receiver @ 24 volts..
The Bronco is also wired to provide 24 volts for my other military radios such as the PRC-174 when operating “tailgate portable” at campsites.
Site selection is important! I stopped at this shady spot and then unloaded the truck in 100° + F heat. Whew. Upon initial power up checks I noticed a periodic loud raspy “DZZZZT” occasionally. Then I looked up through the dense tree cover. DOH! Too hot to relocate.
Next time I’ll be more careful in assessing the overall site suitability. Once noted and after I decided not to move, I elected not to install my usual wire antennas under this 3 phase HV line. This was not a show stopper but just an annoyance. Improvise, Adapt, Overcome.
Got Comms ? Yes. Mission Accomplished.
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For more information on the PRC-174, take a look here:
https://www.n6cc.com/prc-174-hf-manpack-radio-set/
More on the AN/PRC-47 look here:
https://www.n6cc.com/the-prc-47-hf-ssbcw-transceiver/
Details on the TRA-967:
https://www.n6cc.com/racal-tra-967-3-transceiver/
UPDATED 14 April 2024
A signal I couldn’t avoid hearing with my trusty BC-348, S-120 or HA-350 receivers was the Russian дуга Over The Horizon Radar (OTHR) that they had built and operated near Chernobyl in Ukraine.
It is still a popular topic all over the Interwebs. Here’s my take, plus some fun with satellite photos and a Slide Rule to explore some facts and myths about these systems:
Two other OTHR installations had been fielded by the Russians as they developed this system. The first, experimental one was located near the port of Mykolaiv on the Black Sea, the other in the Russian Far East near Komsomolsk. We probably heard all 3 at times.
The DUGA-1* system near Chernobyl was also known by many as “the Russian Woodpecker” for what its 10 pulses per second sounded like. From Wikipedia; here in 1984 interfering with the WWVH Time/Frequency broadcast from Hawaii. File courtesy Rolypolyman:
https://upload.wikimedia.org/wikipedia/commons/5/5b/Woodpecker.oggTo me, it sounded exactly like a helicopter, the UH-1 Huey to be exact. Why? 10 pulses per second made by the blades of the 2-bladed helo rotor = 5 Rev/Sec. Times 60 seconds/Min = 300 RPM. That’s exactly the rotor speed of a Huey in normal flight. But I digress….
These radar pulses produced a massive level of worldwide radio interference to high frequency communications all over the mid-HF bands in the mid 1970’s to the late 1980’s. Those services included shortwave broadcasting, maritime, aviation, utility, military, commercial, navigation and scientific services. Also included were many frequency bands used by Ham radio operators such as myself. It also interfered with Radio Moscow.
It was also reportedly heard on wired telephone systems, stereos and car radios, especially in Europe.
дуга “DUGA” (Arc in Russian). Arc probably indicating its over-the-horizon mission. To achieve “long range” it used the ionosphere to bend its transmitted pulses back down, well beyond the curvature (horizon) of the earth. Something a conventional microwave “line of sight” radar cannot do.
Its signal was plenty loud in the U.S. at the time with its massive peak radiated power estimated at 10+ megawatts EIRP to 40 megawatts ERP (estimates vary). I’d like to see the azimuthal gain versus frequency plots. Has anyone modeled this complex array with EZNEC?
Note that the US/Canadian NORAD Command operated the DEW (Distant Early Warning) Line across the Alaskan/Canadian/Greenland arctic. It used line-of-sight microwave radars and was not intended for nor capable of “over the horizon” detection of Russian bombers and missiles. It was replaced by satellite-borne detection systems.
The gigantic DUGA-1 receiving antenna is 500′ tall and nearly a half-mile wide with its broadband cage dipoles fed by open wire transmission lines and linear wire reflector screens . There are actually 2 arrays here, one “small” and the other much larger. Likely for receiving high and low frequency return pulses respectively. I’d have to visit with a tape measure.
There are many You Tube videos of this antenna array and probably hundreds of online photos. Sadly, NONE of them were taken by an Electronics Engineer!
(I wonder if there is an SO-239 Connector on it somewhere. Just saying…)
Below: The antenna array installation near Chernobyl, that camera was facing west. The individual towers seen at each end of each array support the hundreds of reflector wires which make the system uni-directional off to the northwest.
These reflector wires also reduce the effect of signal pulses arriving from behind it 134+ milliseconds later (after these powerful pulses circled the Earth at times). “Front-to-Back ratio”. Photo credit Ingmar Runge.
(Can you find the man in the photo below?)
DUGA Radar antenna array. (Man on central tower at the bottom) Photo credit: Peter FrancThe Ignoraty and Conspiracy Whacko’s described its purpose as mind control, weather control, Russian HAARP, a death ray, an earthquake trigger, etc. (Actually, it does control their minds.)
Dude! Like it totally caused Chernobyl to freakin’ EXPLODE! and THEN Explain Hurricane Katrina to me. Huh! Huh!
CNN opined in a March 4th 2019 article that it has “a far more sinister and mysterious reputation.” CNN continues: “its true purpose and the important details of its functioning are covered in mystery.” (Umm no CNN, it’s purpose and function was EXACTLY understood – 40 years ago.)
That CNN Travel article included a map with the locations of the radar and the Chernobyl nuclear power plant (reversed – ahem…). “CNN: News you can trust”…
The radar sounded like that recording, a staccato pulse train of about 10 pulses per second, however spread over a very large bandwidth due to the fast pulse risetime. Where Bandwidth = 0.35/Pulse Risetime.
Individual pulses were observed having bandwidths of between 40 KHz and up to 800 KHz. This varied as the individual pulses contained variable BPSK modulation data.
It jumped around in frequency as they adjusted it to deal with HF propagation realities, appearing randomly at between 5 and 28 MHz (sources quote different limits at different times) with higher harmonics in the HF spectrum. Transmissions sometimes lasted several minutes on each frequency before they moved it to another.
The above 2 main DUGA-1 broadside antenna arrays (NATO variously Code named Steel Yard or Steel Work/s) were built along a carefully surveyed axis line of 053/233° True
Below: See Google Earth 51° 18.30N 30° 4.00E. (I used the “Line” Ruler tool to measure the azimuth of the yellow line that I inserted in this satellite photo along the array axis. Try it. It runs 053°/233° True) That orientation was no accident.
This is the receiver site; its abandoned/dismantled transmitter site is 57 km away to the northeast, built on that same 053/233° axis.
Which Way? The T/R system emits and then receives the reflected return signal at right angles to the dipoles/reflector wire arrays off to the northwest on an azimuth of 233+90=323° True. If you plot that Great Circle azimuth from the transmitter site, it goes over eastern Europe, Scandinavia, Greenland, Hudson Bay, Ontario then directly over the ICBM missile fields in north-central U.S. Check.
Nothing “sinister and mysterious” about it. It’s a Radar. The “target” was the US ground-based missile deterrent force they wanted to monitor. “Important details”. How about range capability?
Timing is Everything With its 10 pulses-per second, the interpulse period is 100 milliseconds. As every radar operator knows, radar pulses (radio/light) travel 328 yards per microsecond. That works out to a one-way distance of about 18,000 miles before the next pulse is transmitted. Since radar is a round-trip system, the max detection range is half that, about 9,000 miles before the next pulse is transmitted, deafening the receiver to any return echoes.
However, that 9000 mile distance (time available between pulses) has to include extended “side” trips up to the ionosphere and back, at least twice, likely 3-4 times. This depending upon the operating frequency, ionosphere height and density at the moment. Also, the Transmit/Receive “T-R” switch that protects the receiver from the massive transmitted pulse needs some recovery time, as does the receiver itself.
So the effective detection range to a target would be still less; more like the 5,000 ground miles (8000 km) to the center of the ICBM missile fields from DUGA-1.Hence the 100 millisecond interpulse period. Check.
There CNN, solved if for ya. “Important details covered in mystery” revealed by a kid with a 4-tube Hallicrafters S-120 shortwave radio, an old Heathkit oscilloscope and a simple slide rule. Of course the USG also had CORONA satellite or SR-71 imagery to confirm the structures.
Why there? They located the radar in the southwest part of the then USSR (in Ukraine) to try to minimize HF radio propagation disturbances over or near the north polar areas. These are caused by charged particles in the solar wind interacting with the Earth’s magnetic field which is concentrated at the poles. Think “Northern Lights” etc. Check.
I’ve chatted with dozens of Russian Hams over many years from locations throughout the US; HF radio propagation over the north pole is certainly problematic. HF morse code (pulses) arriving from Russia via the ionosphere have a very characteristic and well known polar/auroral instability known as “flutter”. This is caused by multipath through the chaotic ionospheric medium above the north magnetic pole. All day every day.
Below is a QSL (contact confirmation) post card I received in 1977 from Vlad, at club station UAØCDS from a morse code contact I had with him “over the pole”. Note that his classic Soviet era QSL card illustrates the shimmering green Northern Lights curtain above the Reindeer sleigh.
Probably common sights in his local area. Vlad was in the Siberian city of Sovetskaya Gavan, in the Russian Far East, (coincidentally about 150 miles from DUGA-2). My signal would also have had that characteristic “flutter” as he received me. When you hear it, you immediately know the station is over the pole in Russia or even India or Southwest Asia.
(The DUGA-2 installation at Komsomolsk operated along an azimuth of 40.0° True, also aimed directly at the same ICBM sites in the north-central part of the U.S. The Russians also selected the Far-East site as it mostly avoided unstable ionospheric propagation conditions over the north polar regions.)
High Frequency Direction Finders (HFDF) systems (and eventually even Hams) had accurately located the transmitters at the time.
Powering the OTHR System: Ohm’s Law would suggest that DUGA-1 was not built immediately adjacent to (15 km from) the Chernobyl nuclear power plant (NPP) to provide it with limitless electrical power as many have asserted. (Mind-controlling Death Rays and Earthquake Triggers DO require enormous power however.)
This is the receiver site which would consume relatively little power as compared to the requirements of the massive transmitter located much further away. Even then, the estimated 10 MW pulse transmitter with its roughly 3% Duty Cycle (3 millisecond pulses spaced 100 milliseconds apart) = 300 KW average. That, plus assumed inefficiencies would barely be noticed by the 3500 megawatt capacity of Chernobyl with all 4 reactors operating.
It is more likely that particular receiver site was selected in Ukraine to be in proximity to suitable housing and civil infrastructure (Occam’s Razor applies). The nearby (doomed) town of Pripyat had been build to support the nuclear power plant construction and operations. Both installations would require large staffs. Kyiv was also relatively close by.
Today there are remains of a single 3 phase power pole line heading directly from the Chernobyl NPP transformer/switch yard to the south towards Kyiv. There is a visible tap 4.8 miles down this line which then heads southwest over to the DUGA receiver site. Recognizing that this site was built several years after the power plant and its national power grid connections, that tap makes sense.
The transmitter site looks to be powered by the local grid in nearby Chernihiv rather than by the Chernobyl NPP directly. It is easy to follow the (only) twin, 3 phase power pole lines and associated service roads leading WNW from that city over to the transmitter site 40 km away. No power lines are seen heading from Chernobyl to the transmitter site or any other power lines leading to the transmitter..
Propagation studies: Today there are the remains of a what appears to be a small Wullenweber-type or related CDAA direction finding receiver antenna nearby. The site is 1.6 km SW of the receiver array along nearly that same 233° array axis. Thus also putting it in the DUGA transmitter antenna system pattern side-null to protect it from the transmitter pulse energy.
That HFDF (NATO – FIX 24?) site is generically known as a круг “Krug” (circle in Russian) and has been reported to possibly include an ionospheric chirp sounder. Makes sense – queuing DUGA to the optimum frequencies for operation. The word азимут (azimuth) is not surprisingly seen on an interior control panel photo. Indicating to me that this detects favorable propagation paths both in frequency AND direction, 323° true being the most interesting to them at this DUGA installation.
It would be used to measure the variable ionospheric height as that is essential to knowing where your signal is going to/coming from.
(DUGA-2 in the Far East also has a CDAA antenna array 3 km away from that receiver site, similarly in the transmitter antenna side-null to protect it. There are remains of a similar CDAA antenna installation at the receiver site in Mykolaiv. These are also presumably ionospheric sounders used to queue the operators to the optimum frequency/azimuth of operation.)
OSINT doesn’t seem to report if the Duga receiver antenna system or its associated transmitter antenna was actually designed to be a steerable phased array or more simply a fixed directional system. That would cost them complexity and Gain. Also, their intended radar targets didn’t move much in azimuth. No need.
Without seeing photos (taken by an EE or RF Engineer) of how all those open wire transmission lines are terminated I cannot determine. Pulse analysis indicated it might have a range resolution of perhaps 10 miles but did they need good bearing resolution? The ionosphere is big, squishy and always moving. “Komrade! Is that a missile or Montana?”
FUN FACT: I noticed when DUGA often shifted into the internationally allocated Amateur Radio ham bands (in violation of international law which the Russians signed: nothing to see here, move along). When it showed up with impunity that 10 PPS signal obliterated all communications on those frequencies.
When THAT happened I found myself needing to test my transmitter and electronic CW keyer on frequencies allocated for ham radio use. Testing my keyer at 10 dots per second, or thereabouts, on the DUGA frequency, or thereabouts, I could often get them to move off frequency (coincidence?). My puny 40 watt Hallicrafters transmitter CW signal was significantly stronger than any reflection they could detect off a missile, exhaust plume, disturbed patch of ionosphere, aircraft or maybe even the North Dakota ground clutter.
Doing my part in the Cold War…LOTS of other Hams tested their equipment in a similar manner. “Woodpecker Hunting”…
Must have driven their operators crazy as it was apparently fairly easily “discouraged”, accidentally of course. I don’t know what kinds of pulse-forming networks** or signal processing in the receivers they used at the time but it was probably adequate given the technology available. Receiver transversal matched-filter gymnastics notwithstanding.
Russian engineers were/are particularly good at designing pulse forming networks and pulse power machines. Apparently not so good at operating nuclear power plants.
My chirpy Novice transmitter pulses probably looked like up-doppler shifted INCOMING! “Komrade Kononel! They launched!” “Nyet, that’s just Tim again”.
Enterprising Hams designed filter circuits and even sold the “Moscow Muffler” Woodpecker filter and others for Ham/shortwave receivers. It was only partially effective because the Russians (and especially the ionosphere) caused random changes in the received signals. Hard to keep up.
The DUGA-1 site was abandoned in 1989 due in part to significant radiation contamination from the explosion and melt down of the Chernobyl nuclear power plant (and the implosion and melt down of the “Union of Soviet Socialist Republics” and the Communist Party).
There is wide speculation that the Russians abandoned the system because “it didn’t work” (“work” being undefined). Not so fast. This technology does “work” within the limits of physics, the state of the art and Operational constraints. OTHR signals can still be heard in parts of the HF spectrum, including in Ham bands.
The US and several other countries are operating OTHR systems today. That includes Russia with its relatively new “Kontayner” OTHR systems and its significantly different antenna arrays. What’s old is new again. But that one is another story. Individual Russians are capable of some good science and engineering.
(UPDATE 4/12/24: During Ukraine’s counter attack against the Russian invasion, a Ukrainian 650 km drone strike hit the Russian Kontayner OTH radar receiver site at Parapino, Mordovia. BDA pending.)
Today, all 3 DUGA transmitter and associated receiver sites have been abandoned, collapsed and then looted for scrap. However the Chernobyl system receive antenna still stands and is now a local tourist attraction. The other sites and infrastructure are gone, being reclaimed by the forests.
Below: Some remains of the Chernobyl DUGA radar electronics system, November 2017. I wonder what the background radiation levels are in there. (Check those air filters Komrade.) Photo credit Jorge Franganillo.
The above-mentioned 2019 CNN article closed with this: “The Soviet Union may have gone forever but its ghosts still haunt Ukraine.”
Indeed.
For some really excellent analysis and background on “DUGA” be sure to take a look at Ringway Manchester’s series on Youtube about this and other communications topics.
- I’m going with DUGA-1 for the Chernobyl installation. “Open sources” widely disagree on the number suffixes of these 3 DUGA systems, seemingly randomly assigning them by location. Not helped by Russian political warfare “Active Measures” programs including military deception (maskirovka) and disinformation (dezinformatsiya) campaigns. At the time they identified this site on Russian maps as a “Childrens Camp”. Of course they did. There was such a camp nearby, close enough.
“The AS-1729/VRC is an omnidirectional, vertically polarized whip antenna assembly that provides transmission and reception of radio signals (very high frequency (VHF)) between 30 and 76 MHz.” TM 11-5985-262-15
BACKGROUND: This antenna was designed for installation on various vehicles as part of Radio Sets AN/VRC-12 and AN/VRC-43 through 49 (RT-524/RT-246 radios).
These as replacements for the 1950’s AN/GRC-3/8 systems with their AB-15/GR base and MS/AB series antenna masts.
The AS-1729 antenna is seen below on the M-151 “Mutt” drivers side, held bent over by the tie-down (range killer) rope kit. The AB-15/GR antenna/masts for the R-442 auxiliary receiver is also seen here tied down on the passenger side. The setup is either a VRC-12 or VRC-47.
The AS-1729 was also used with the vehicle-mounted AN/PRC-25 and PRC-77 systems including the AN/VRC-53, AN/VRC-64, AN/GRC-125 and AN/GRC-160 respectively.
This antenna system with associated radios was deployed beginning in the early-mid 1960’s and was widely used in Vietnam on jeeps, trucks, armored vehicles, shipboard, combat craft, PT Boats and fixed installations.
Below is a photo of an AS-1729 antenna mounted on Fast Patrol Torpedo Boat PTF-17 along with 2 HF antennas, the AS-390 UHF “spider” antenna and radar antenna. A second AS-1729 antenna was later mounted on top of the mast to increase range and to improve the radiation pattern of the associated VRC-46 system aboard..
A pair are seen below aboard a STAB: Strike Assault Boat in Vietnam.
These systems continued on into the 1990/1991 Gulf War as the SINGCARS frequency-hopping systems continued to replace it in Line combat units. They soldiered on well into the 1990’s and beyond in Reserve and NG units until replaced. I have seen a base unit with a 1993 contract date.
DESIGN: The antenna consists of two mast sections, the upper AS-1095 and the lower AS-1730 connected to the MX-6707 Matching Unit/Base assembly. The 2 fiberglass mast sections are center-fed in a 10′ high, vertical dipole configuration.
Note that this antenna is NOT a base fed, “quarter-wave” vertical that would ordinarily require a ground plane to control the base impedance and to reduce ground losses. It’s a different animal. As a center-fed vertical it ideally does not need a ground plane.
The center-fed design works by keeping the highest RF currents (that cause the actual radiating) further up the whip near the center and further away from vehicle/installation obstructions near the base. This, versus the max current/radiation that actually occurs in the spring (!) area of a base fed vehicle antenna closer to the lossy ground and buried next to a pattern-disturbing fenders and other metal parts. It’s a very good design.
The internal coaxial transmission line driving the center feed point is terminated by a choke balun residing inside the lower AS-1730 mast section, denoted as L1 in the schematic.
The MX-6707 provides switchable matching components over the entire frequency range as well as the base mount and spring assembly. The base unit matching circuits can be set to the radio’s operating frequency by remote control via a cable from the radio or manually selected by a rotary switch located at the base.
Ten bands are provided from 30-76 MHz. The below image is from a “parts set”; band switch segments as shown. Note that they are non-sequential. The manual band switch is to be rotated clockwise. Note the missing screw from the water drain hole below the BNC connector.
The performance specification states that the VSWR will be below* 3:1 within any selected frequency band; the nominal feed point impedance at the BNC connector is “50 Ω”. The power handling capacity is 70 watts.
(*In practice the VSWR can exceed 3:1 depending upon the actual installation in the field, Ref. 112. It will then be significantly worse when tied down on a vehicle as seen in the top photo.)
The Gain is not specified as its measurement is subject to many caveats in a multi-frequency system and deployed in random installations as these are. However subjective, it would approach that of any center fed vertical antenna of the same length minus small matching circuit losses. (Gain in dBd = decibels as referenced to a dipole)
A 10′ long center-fed half wave dipole has a natural resonant frequency of around 46.8 MHz. Operating it above or below that frequency requires some reactive elements to transform the resulting impedance closer to 50+j0 Ω. How was that implemented?
The MX-6707 base unit contains a 12 position band switch for selecting the appropriate reactance elements to achieve the best match / lowest SWR within each selected band segment. These include inductors and a piston type capacitor, all adjustable per the schematic. There are 2 null positions. See below:
The Depot Level tuning and adjustment procedure requires an Admittance Bridge to measure the network conductance/subceptance under test. Also required is an elaborate holding fixture which includes* a 10×10 foot square metal ground plane to control the systems’ local environment while being adjusted. Lacking that, I just used some trial-and-error adjustments on the bench and then tested in-place with a simple SWR meter. It works. Improvise, adapt, overcome.
- I assume the Depot procedure made an attempt to control the test antenna’s local environment to minimize that variable during factory alignment or repair.
IN HAM RADIO SERVICE: I have used these antennas mounted on the old ’71 Bronco using the SC-D-189023 “sugar scoop” vehicle mount. It is connected to the VRC-7 (RT-70) VHF FM radio system on the 6 meters Ham band. These are very effective and rugged mobile antennas for low-band VHF applications, as designed.
I am currently using this antenna in a fixed location mounted on a building as seen below. This installation uses the Lightweight Mount, NSN 5985-01-215-9404. When adjusted and manually band-switched accordingly, the antenna provides good performance on both the 6 meter and 10 meter US Ham Radio bands.
AS-1729/VRC VHF Whip Fixed InstallationTo use the antenna for 6 meters Ham Radio operation (in my case centered on 51.0 MHz) just set the Band switch knob to the 47.5 to 53 MHz band and it will work fine. To further reduce the in-band SWR at 51.0 MHz I adjusted L5 in the base unit for minimal SWR at that frequency.
For 10 meters operation (out of band) centered around 28.5 MHz I set the band switch to the 30-33 MHz position and adjusted C8 for minimal SWR.
As installed above, the SWR on 6 meters is 1.2:1 and on 10 meters it is 1.6:1, fed by a short length of RG-213/U coax to the radios. Both quite acceptable with good “DX” performance.
(The antenna will probably work adequately further out of band on the 27 MHz CB band if necessary although I have not tried to retune this one down that far. When set to the 30-33 MHz position and further adjusted to 28.5 MHz as above, the SWR inside the 11 meter band is below 2.4:1. That’s certainly usable if needed in a pinch, especially if the coax is pretty short as in a vehicle. This question comes up occasionally.)
The antenna is nominally designed for mounting on a vehicle which includes a “grounded” surface in the near-field by default. (Note that in Navy service aboard fiberglass PBR and STAB boats as well as plywood deck structures on PTF’s there is no significant metal near the base.)
To simulate “a vehicle” in my base station installation I ran a short ground braid strap to the adjacent 8 foot aluminum gutter thinking this would “help”. This is obviously NOT a “ground plane”.
It turned out this “ground” configuration made the SWR significantly worse in this installation on a wood-frame building with installed gutter. Although aluminum rain gutters make surprisingly good antennas, this indicates that the antenna is sensitive to metal objects in proximity in the near-field.
I removed the ground strap, all is well. YMMV. (Lightning protection or striking HV power wires in vehicle operation is another matter; lightning around here is very rare but something to consider.)
AVAILABILITY: As the SINGCARS radios with their AS-3900 broad band (resistively-loaded) antennas continue to proliferate, many tens of thousands of these narrow band antennas have become excess to the US DOD. They show up on the usual online places and at ham radio and military vehicle swap meets. However “asking prices” seem to be crazy expensive as military vehicle guys seek them for “that look”, often just as a proper accessory for that era vehicle or maybe for a flag pole on the fender. Why not…..
BE AWARE: Make sure you perform your preventative maintenance checks. Pay attention to your Specialist – She knows What’s Up! US Army Preventative Maintenance Monthly “PS” Magazine, June 1999:
The MX-6707 had some water intrusion issues over the years as noted in the cartoon above. The leaks were primarily caused by cracks in the Lexan housing caused by over-torquing the vehicle mounting ring bolts or the spring bolts. Different gasket seals were also fielded to reduce capillary intrusion by water. Life aboard ship in a corrosive sea water environment was especially tough. The drain hole in the bottom was no accident; if you ARE letting water out, you already have a problem.
PERFORMANCE: With this base antenna I can work 6 meter repeaters up in the Sierra Nevada mountains up to 75 miles away (nearly LOS) with a 5 watt FM signal. It also worked great on the truck at remote campsites working my buddies with the PRC-25 and PRC-6 sets on 51.00 Simplex.
It also works great with my VRC-10/RT-68 VHF FM transceiver on 6 meters simplex at home.
As we experience good propagation conditions in 2023 on 10 meters, I can easily work cross country or into South America, Asia and Europe on CW or SSB with the PRC-174 man pack set running 20 watts. The antenna works great on both Ham bands.
If you find one in decent shape they make excellent, rugged antennas for mobile or fixed base ham radio ops.
For further reading and a Deep Dive into the performance of these antennas in ship board and in more general applications (including “out of band” performance at an antenna test range) see Reference 112: ANTENNA AND RF DISTRIBUTION SYSTEMS APPROACHES TO MEET AN/VCC-2 COMMUNICATIONS REQUIREMENTS ON AMPHIBIOUS SHIPS. Technical Document 196
AR
UPDATE 1/18/2024 In an effort to encourage more field operations by Hams, especially with military field radio gear, the following After Action Report is posted.
This was my Military Communications Field Training Exercise: (ARRL Field Day 2023). Need emergency PACE “back channel” E-Mail comms while deployed?
(PACE = Primary Alternate Contingency Emergency communications plan and equipment.)
Ham radio Field Day is an annual, National emergency communications preparedness exercise. Typical Field Day draws upwards of 30,000 participants in the US and Canada.
My operation class was “1B EB” (1 transmitter, off-grid, battery powered, located in the ARRL East Bay section). Effective training for everyone.
I set up a hasty field station on Saturday at the location of the former NIKE SF-25 Surface-to-Air missile battery and operated for a few hours. This NIKE site was operational from 1956-1959 providing air defense to the San Francisco bay area from Russian bomber attack.
My location was in the park that now occupies the site near the air search radar system on “Rocky Ridge”. The setup was on a picnic table in a leafy glade (drone countermeasures !) alongside the creek at the bottom of the canyon. This site is surrounded by 200-250 meter high hills on 3 sides. Near Vertical Incidence Skywave operation was the plan of the day.
The main goal was to exercise my equipment for portable, battery powered field ops using the 20 watt PRC-174 HF Manpack set mounted on the ALICE backpack frame; I was running CW and SSB voice. The antenna was a 20 meter long Inverted L wire tossed up in the trees over a ground counterpoise wire. Simple quick.
Note: NIKE missile batteries had AN/GRC-9 HF field radios for network site-site comms.
Another goal was to exercise this system on the Winlink HF / Internet EMail system. It worked well sending and receiving my test EMail via an automated HF-Internet Gateway node in Reno NV, a 275 km shot from here. There are scores of these nodes around the world. You can always connect with many of them
Lacking an actual military terminal, my setup uses a PC Notebook “Glass Terminal” running Vara HF software through a Signalink interface to the PRC-174.
It worked well and is very handy from “The Bush” if local or regional Internet, WiFi, Cell coverage or utility power is down. There was none of that at this FOB.
I also exercised the setup on radio-teletype “RATT” with a pre-planned sked with a buddy doing a similar “military” Field Day operation near LA using his PRC-47, CV-2455 and a UGC-74 teletype terminal. I was up on 7087 kc, 850 cps shift, Space High at 20, 21 and 2200Z as planned, calling CQ Clatternet.
Alas, he was having equipment problems, so no joy on RATT this time although we have done this before. This is training – better to uncover the Gremlins now.
“Comm works 100% of the time 50% of the time.” Murphy’s Laws of Combat.
I also did not hear any Ham RTTY (170 cps shift) on 40 meters that day. However there were LOTS of CW and SSB field stations on the air then.
A few photos of the highly portable setup. Nothing to see here, move along:
Another crappy day in the Woods. That dark green ground cover in the background is poison oak – an excellent perimeter-defense system. Don’t drag your antenna or ground wires through it.Below: The complete CW/Voice/RATT/RTTY setup. The Notebook USB drives the Signalink interface; it sends/receives Mark/Space audio tones to the radio Audio connector. The radio then operates in Upper Sideband, Audio Frequency Shift Keying mode to generate and decode that Baudot waveform.
PRC-174 HF RATT SystemThe FLDIGI software runs this and nearly every other mode including CW, Packet, various PSK modes, MT-63, SITOR and many other “digital” waveforms. It even displays analog Weather FAX satellite imagery sent by the Coast Guard on HF channels. Very versatile. But Morse Code with the J-45 Knee Key is still my favorite – always works!
Below: I also had the RACAL TRA-967 (formerly owned by Saddam Hussein’s army in Kuwait) along guarding 52.525 mc FM Simplex for local Ops. As expected, I heard no 6 (or 2) meter Ham activity down in this canyon but I could listen to the local California Highway Patrol and Parks and Fire Depts low-band repeaters down between 42-47 mc. Handy for situational awareness.
RACAL TRA-967 VHF Low Band FM Transceiver for 6 metersThis set has good interoperability with PRC-6, 25 and 77 sets as well as the VRC-12 series vehicle/fixed-base sets. It is also interoperable with modern, commercial Ham equipment. For all your tactical Commo needs!
Below: All the HF station accessories besides the PRC-174 on the ALICE pack frame fits inside that little day pack for transport. Including the PC Notebook, various dipole and other wire antennas, coax, handset, key, headphones, the whip antenna and mount, speaker, notebook, small solar panel, coax adapter kit etc. Ready to go anywhere.
Over a few hours I was easily able to work many field stations in Washington, Oregon, California and Nevada on 40 meters, mostly on CW with some SSB voice.
Got Comms? Yes.
Mission Accomplished.
(For more information on the PRC-174 and field ops, take a look here)
https://www.n6cc.com/prc-174-hf-manpack-radio-set/
Updated 7/3/23
This is a RACAL TRA-967/3 VHF FM transceiver that was formerly operated by Saddam Hussein’s army in Kuwait during the 1990-1991 Gulf War. AKA Operations Desert Shield, Desert Storm, Granby (UK). The faded paint markings on the carrying bag are translated from Arabic as “9 F 17”, possibly a unit designation.
Iraqi TRA-967/3 Gulf War “Bring Back”The following is a brief description of the radio and my observations on its design, capabilities and operation. These sets were made in England; this one sports component date codes including week 40 of 1978. It is well designed, functional and very capable. I like it.
Some basic specifications from the manual:
- Frequency coverage: 36.000-75.975 mc
- Channelized in 1600 channels spaced 25 kc apart
- Power Output 3 watts (/3 version), 1 watt (/1 version). NBFM, 5 kc transmit deviation. Planning range approximately 8 km.
- Power supply is 12 volts nominal from NiCds or 10 C Cells in clip-on battery boxes or an external vehicular supply. RX=50/120 ma (standby/receiving), TX = 1.4A (3 watt version)
- Battery life (3W) is approximately 11 hours, 8:1:1 (Standby: Receive: Transmit)
- Operating modes include: ON – (RX carrier squelch*), Whisper mode (20 db mic boost), Rebro (relay) mode (with 2 connected transceivers). It also has 150 cps T/R tone squelch in Rebro mode plus a Noise (squelch disable) function.
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- The 150 cps “pilot” tone is transmitted in every mode.
- Frequency display illumination is via tritium/phosphor lights, now long dark.
- Antenna options include a collapsible 7-piece, 1.2 meter whip with flex gooseneck and a BNC connector for an external 50 Ω antenna or RF amplifier.
Some Context: According to a former RACAL employee these sets were developed primarily for the export market to foreign governments, militaries and paramilitary groups. It is a capable although less expensive alternative to more “ruggedized” equipment such as the contemporary Clansman series. These apparently sold quite well, I can see why.
Saddam bought a lot of RACAL equipment like the TRA-967, including its “sister” HF radio, the TRA-931 seen here inside a captured Iraqi/Russian BMP-1. (Authors photos)
Captured Russian BMP-1 Armored Command Vehicle in KuwaitBritish Racal TRA-931 HF transceiver in captured BMP-1However this BMP Command vehicle did not include the TRA-967 for VHF FM; it used the more powerful 1960’s Russian “Magnolia” vehicular set instead as seen below. They have limited but useful interoperability. Maybe Saddam’s embarked conscripts carried a TRA-967? Below is the R-123M Магнолия inside that aft, right hand door.
Soviet R-123M VHF FM Tank Radio(This armored vehicle fared much better than Putin’s BMP’s in today’s Ukraine….) But I digress.
An obvious TRA-967 comparison could be made with the US AN/PRC-25 or the AN/PRC-77 VHF FM manpack sets; those designs from about 10+ years earlier. The PRC-25 (below) even included a vacuum tube PA stage; the PRC-77 quickly updated that design with a transistor. The TRA-967 is all solid state.
TRA-967 size comparison with AN/PRC-25They have very similar capabilities and intended usage. They are interoperable where their frequency coverage/selection overlap. The narrower transmit deviation and IF bandwidth of the TRA-967 versus the PRC-25/77 enables the 25 kc channel spacing but they are still interoperable with adequate audio recovery.
The lowest operating frequency the TRA-967 provides is 36 mc versus the 30 mc of the PRC-25/77. However its 25 kc channel spacing gives the TRA-967 1600 channels versus only 920 for the PRC-25/77 with their 50 kc channel spacing, despite its wider frequency coverage.
The TRA-967/3 3 watt output is about 1 db more than the PRC-25 and it is also smaller. It is less than half the weight of the PRC-25 but maybe somewhat less rugged as a result.
This one receives great with good sensitivity and fidelity on the local Highway Patrol and other low band VHF Public Safety channels as well as transmit/receive on the 6 meter Ham band.
I did have to replace the handset coil-cord as it was shot. I don’t know what the significance of the handsets green and red earpiece/mic denote. (Stop Talking – Listen!)? Always good OPSEC or even personal advice. Anyone?
I even like the radio’s color – British Racing Green ?
TRA-967 and PRC-25 Size ComparisonBoth sets provide infantry squad/platoon/company units with short range, reliable tactical comms up to about 8 km depending upon terrain. Both sets can be integrated with vehicle mounts, antennas, crew intercoms, vehicle power supplies as well as their attached battery packs.
The TA970H 25 watt RF Amplifier was available for vehicular/base station service; that mounts in a special rack with the transceiver.
Below is the handy MA 968B battery box for 10 easily obtainable “C” cells. Simplifies logistics support downrange. The MA-968A NiCd box is similar but they are rechargeable.
Note: I have stopped using Duracell batteries in my equipment whenever possible. Some years ago they changed the design or manufacturing process and now I find that too many of them will eventually “leak”. The alkaline chemistry uses corrosive potassium hydroxide which then forms potassium carbonate, that white powder seen leaking. Some cells even leak in original packaging WELL before their “best by” date. Certainly, DON’T leave them in standby equipment. Beware, YMMV.
Above: The black “screw” in the lower left hand corner is a 20×5 mm, 2.5 Amp fuse.
Although well sealed, it takes a screwdriver or a penny and a bit of time to open up the box to change the cells and then reassemble. But it works, I like it.
RACAL MA968B Dry Cell Battery Box InternalsThe radio’s design includes good environmental protection with a gasketed 1-piece aluminum case. It comes with a nylon canvas shoulder bag with extra pouches for the whip antenna and handset. There are provisions for 2 audio devices such as a handset and speaker.
Repairability access to the 2 PC boards is good. Many test points are available although I find that fault-finding is difficult due to parts density and limited published component location and PCB layout wiring drawings.
The late 1970’s technology includes many low power CMOS devices and some ECL logic in the PLL circuit. It has a clever 5-voltage power supply regulation system and an equally clever “battery saver” system to reduce power consumption while standby/receiving.
A known weak spot with these radios is the tantalum capacitors that are used extensively. They have a high failure rate after 45+ years; there is some bad electro-chemistry Booga Booga going on inside them these days. I am sure they were fine during their expected service life.
I have had to replace 5 caps plus a shorted relay coil snubber diode (which does not appear in the schematic!) in this example but the set is otherwise reliable. Below are the 2 main (RF and Synthesizer/power supply) circuit boards:
TRA-967 RF BoardTRA-967 Synthesizer/Power Supply BoardMost of the tantalum capacitors have either a blue or red epoxy body; the resistors are held in place vertically with the little red and green plastic vibration mounts. Note the absence of MFP, solder mask and limited use of silk screening of component labels due to the dense layout. The set has very tight packaging from before the time when ASIC’s or LSI circuitry became commonly available. It’s a very good design for the times.
These sets have a reasonable presence on the Interwebs for additional information and peripherals descriptions. Not much out there regarding development or sales/deployment. RacalRadio@groups.io is a good source for current information on Racal equipment. For further circuit details see Ray Robinson’s excellent tuberadio.com website on the TRA-967, Reference 109.
Some field ops and interoperability evaluations were held at the recent west coast Military Radio Collectors Group event. We operated over a few hundred meters radius on 51.00 mc. That frequency is commonly used by US and other Hams operating military gear.
We had the TRA-967, PRC-6, PRC-10, a Czech RF-10 and a ricebox on the net. They worked together very well within their individual deviation specs.
The TRA-967 can tune 52.525 mc for work on the US 6 meters simplex calling frequency, something the PRC-25 https://www.n6cc.com/prc-25-radio/ can’t do due to its 50 kc channel spacing. Both radios can also work on the 4 meter Ham band in Europe and elsewhere where authorized. Also note that neither of these sets can provide a transmitter “offset” to work with Ham repeaters. No worries, simplex works.
TRA-967 ready for 6 meters opsBelow is my 2023 Field Day portable setup in the woods. The TRA-967 was along for 6 meters activity. However I was located in a deep canyon using HF NVIS to work CW and SSB on 40 meters: No 6 meter signals were expected into this location. But the radio did monitor the local Highway Patrol and local parks police and fire departments (situational awareness).
TRA-967/3 at N6CC Field Day 2023 site Stay tuned for reports on future field ops.
AR
NNNN
We put together a display highlighting the Navajo Code Talkers (NCT) for the Veterans Day event at the Veterans Memorial Building of San Ramon Valley (CA), November 11, 2021. We had several hundred visitors over this 4 day special event whose overall theme was recognition of the 75th anniversary of the end of WWII in 2020.
Very Politically Incorrect through today’s lens Members of 14 different Native American tribes participated as “code talkers” during WWII, the Navajos are perhaps the most recognized. Above: It appears they were not very impressed with the 1930’s tech TBY radio in a wet jungle. Understandable!
The wartime service of these guys has my total respect – on many levels.
The display included posters of iconic photos of the US Marine Corps NCT’s taken in the Pacific as well as the Comanche code talker assigned to the US Army’s 4th Signal Company, 4th Infantry Division in Normandy 1944.
Posters included the above cover of the Dictionary that the Navajo’s developed. It was used to standardize their substitutes for English letters and the code words for 800 items of military significance that they had to memorize. Note the DOD Declassified stamp on the Dictionary cover (1968). Source: Naval History and Heritage Command. (Reference 104).
Example: The code word for a fighter plane was Hummingbird. The Navajo word for Hummingbird is spoken Da-he-tih-hi. Since Navajo is a spoken language and had never been put into writing; it was quite secure for the purpose. At the time, it was determined that only 30 non-Navajo’s could speak the language; they were mostly missionaries from the US Southwest and none had any “Axis” connections.
This verbal communication bypassed the otherwise lengthy process of encrypting and decrypting each letter of a message via the M-209 Converter (below). The M-209 was normally used for ongoing but otherwise time-perishable tactical comms absent the code talkers.
The M-209 and KeyMat Equipment we displayed included the TBX-2 and TBY-2 as seen in those iconic Pacific theater photos as well as a functioning SCR-284 as seen in the Normandy photo. Included were other items they used including a BC-611 Handy Talkie, EE-8 field telephones and other period infantry equipment including an M-1 Carbine and field/web gear.
I also ran a 3 minute loop of Marine Corps veteran and NCT Peter MacDonald Sr. describing NCT operations on Iwo Jima and an actual coded message that was sent, decoded and acted upon. https://www.youtube.com/watch?v=QmiqnAQTTCI
I also displayed an operational RT-68 transceiver and a PRC-6 handy talkie running on 51.0 mc to demonstrate their use during the Korean War. Native American code talkers also served in that war (as well as WWI) although the extent of their operations in those conflicts is not well documented. The kids enjoyed trying out the PRC-6 and hearing themselves on the RT-68 speaker. (I ID’d as N6CC periodically…)
Navajo Code Talker Display Above: The overall view of this indoor display with posters. Period table cloths, some bamboo poles, the smell of dank camo net and warm MFP vapors. You remember… The GN-45 hand generator to power the SCR-284/PE-104 sat on the grass floor mat.
Here is a closer view of the above. The Mess Kit and Canteen Cup were even demonstrated at a nice Pancake Breakfast provided by the Town Council members for the Veterans .
Navajo Code Talker equipment display Below is the TBX-2 and TBY-2 static display along with photos of each of them being used. The display included the monitor for the NCT video loop. (Thanks to Tom for the loan of the TBX and to Lee for the Carbine, I couldn’t come up with a .45 cal Reising SMG as seen in the upper photo..)
TBX-2 and TBY-2 Display Below is a close up of the SCR-284 and RT-68 with ersatz antenna mount setup: Improvise, Adapt, Overcome….
Navajo Code Alphabet and code word excerpt
As part of the SCR-284 setup, I included the Normandy photo showing the SCR-284 in action from a shell hole. The Comanche code talker (on the right in the photo) is seen using the BC-611 along with the 4th SigCo team.
To illustrate a typical function of a team like this I included a description of how this team could take a call (in code) from a local tactical unit “in contact”. They might request supporting fires and then the team passes it on to DivArty or a Naval Gunfire ship out in the channel or off the coast.
A reasonable facsimile of the English Channel was provided, including a floating model Battleship steaming within 14″ and 5″ gun range. Here the USS Missouri representing the USS Nevada at Normandy, close enough.
Reasonable Facsimile of the English Channel with representative BB ship As part of my usual display setups I included a morse code CW Code Practice Oscillator for the visitors to try out their “fist” on the Navy Flameproof key as above. Always popular with the kids – I show them the “code” sheet, demonstrate Dots ‘n Dashes and then ask them to send their first names. From across the room I tell them what it is – WOW! This really works! The kids pick up the concept very quickly. Digital Communications!
To add some realism to the display I had a URM-25 signal generator hidden under the table. It was being externally modulated by a CD player running continuous 25 WPM 5 letter morse cypher groups in a loop. With the SCR-284 tuned to the URM-25 frequency, turning the GN-45 generator cranks produces loud MCW sound coming from the speaker.
“WOW This stuff really works!” Yes, it does. Then and now….
Although I believe the Code Talkers had no need to use CW, having this live feedback for the radio “cranker” makes this display “come alive” for the visitors. “Let me try it!”….It’s also a good conversation topic on 75+ year old equipment that still works well. How about your cell phone working in 75 years? 75 months? Um…probably not.
I also included an AN/GRA-6 Radio Wire Integration setup connected to the RT-68. This to illustrate the genesis of today’s “Cell Phone System” to entertain the visitors with a mobile PRC-6 walkie talkie-to-telephone interface. This is how your Cell Phone system works…”Wow!”
As part of the overall event at the Veterans Memorial Building (Danville CA) we also displayed other Militaria, including military vehicles, a 75 mm Pack Howitzer and a UH-1H Huey helo parked on a trailer out front.
UH-1H Huey of the Vietnam Veterans of Diablo Valley The helo is great “Eye Candy” and everyone enjoys climbing aboard for a quick mission.
We also had the cockpit from an F-8 Crusader from the USS Hornet museum ship. “When you’re out of F-8’s, you’re out of Fighters”…
The Crusader cockpit is also a big hit for the visitors to sit in for a Photo Op and then a quick Combat Air Patrol mission above the neighborhood.
We have been doing these displays since the VMB was remodeled in 2012 after its original construction in 1925. It is a great place for our 9 Veterans Service Organizations to meet and call “Home”.
Here’s some photos from our 2016 display and the Korean War “Tactical Operation Center” I put together as another display example: https://www.n6cc.com/veterans-day-displays/
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UPDATED 1/16/2022 A friend recently gave me an RT-654A/TRC-77. Also known as the TRC-77A. The RT-654(*) is the basic component of the “AN/TRC-77” set. (“TRC” = Transportable Radio Communications. The […]
PTF-17, PTF’s in general and Coastal River Division 21 Ops: Updated – 3/3/2022 A Work in Progress.First, a little background: Why PTF’s? The Green Water Navy. Despite what several Keyboard […]
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UPDATED 2/7/2022: My favorite “Black Radio” even with its few quirks.Probably the ultimate “SHTF Radio” for trained (or trainable) personnel.Some research, observations and adventures below; probably more than you ever […]
UPDATED 12/29/21 Another favorite Black Radio is the RS-6 set. (RS-6 = Radio Station number 6 per Central Intelligence Agency nomenclature.) Some other sites go into the technical details of […]
UPDATED 22 Feb 2021. The SCR-284 was used extensively during WWII. The basic component is the BC-654-A receiver transmitter. Designed as a portable field radio, the complete field set could be carried by 3 men (three 55 pound loads) or it could be mounted in vehicles. US Army procurement records indicate that 63,972 sets were procured between 1940 and 1945. Reference (74). Apparently all were built by Crosley Corp.
I have had this one since I bought it from Algeradio in Hempstead NY in 1964. Thirty five bucks, earned on my Newsday paper route – many weeks effort! It works quite well and has seen many field ops at various campsites. It was NOS when I bought it as a kid in high school. The scrapes and dings are all mine..
Below: It is set up at a Stanislaus River campsite as my “night stand” so I can talk to the West Coast Military Radio Collectors net on 3985 KC on Saturday nights after I hit the rack (cot and sleeping bag in the foreground). Photo circa 1990…I am still collecting the correct parts so that is a TBX key and an ersatz speaker. I was running it from the PE-103 / PE-104 powered by a 12 volt deep cycle battery. (MAKE SURE you set the voltage switch on the PE-104 to the correct voltage!!)
Looks like I had moved the dipole coax over to the GRC-109. I usually don’t use the whip antenna when operating at a site like this with many big trees for wire supports. Horizontal wires are much more effective for regional chats with my buddies.
It’s a pretty good “woods” radio and is very sensitive and especially fun in a radio-quiet environment like this. Sounds great. That’s an NE-51 lamp wired across the antenna connector so I can tune up the transmitter in the dark – the RF meter is not illuminated and the radium/phosphor dial paint has long since faded out.
SCR-284 set up at my “night stand” on the river – N6CC
Below: Another setup at a different camp, this time running the whip. That whip mount fits the radio and MS – mast section perfectly but it is obviously different than the brown plastic mount usually seen. It is the originally supplied IN-106, a heavy, fragile part. These were quickly replaced by the plastic IN-106A insulator which was much lighter and less fragile for field use.
Like most of my WWII radios, this one still contains all but one of the original tubes. I did replace 8 capacitors in the receiver. The most critical one was the AVC time-constant capacitor (Part number 2C10). In that high impedance circuit a leaky capacitor can cause all kinds of gremlins to appear. Change it out. I also replaced 3 capacitors in the transmitter.
Radioactivity: Incidentally, the meter in my SCR-284 is relatively “hot” radioactivity-wise. More so than any other radio or meter I have. Probably because there is a relatively large amount of paint on the “arc” scale. It puts out about 6 mR/hour as measured with an Eberline E-120 Geiger counter (with detector probe HP-190A) contacting the meter glass. Radium 226 is primarily an Alpha emitter and it stays hot for a long time (half life of 1620 years as it decays into Radon gas).
This detected signal is most likely Gamma radiation – Alpha’s won’t penetrate the meter glass, nor will most Beta’s. It finally damaged the phosphor paint it was intended to excite in this meter. Very, very dim glow these days but the Radium is still there. Don’t disassemble it…There will also be some radioactive Radon gas inside.
SCR-284 Radium paint
(My R-390A Receiver meters also had detectable levels of radiation: The Carrier Level meter read 1.2 mR/Hr, the Line meter read 0.4 mR/Hr. Background during tests was 0.01 mR/Hr. My TBY meter read 1 mR/Hr, my GRC-9’s labeling each read just background. Probably no radium paint used on mine.)
The SCR-284 on the MRCG Net
Above: working the West Coast Military Radio Collectors Group net on 3985 Kc from a campsite. PE-103 powered by a 12 volt deep cycle battery.
One unit that used the SCR-284 was Merril’s Marauders during their jungle operations in Burma in early 1944. Those operations relied heavily upon airdrops logistics since they were well into the interior where no roads existed. The “Ledo Road” built to assist China had yet to be built; the area had to be secured first. The radio equipment used in this campaign is interesting from several perspectives, but it is clear that long range HF was key to the logistics success.
The SCR-284 was used by all accounts but there is a mystery concerning another “long range” set that was there as well. The distances involved were about 200 miles, for example from the battle at the Myitkyina airstrip back to the logistics base at Danjin. A fairly easy shot on CW for an SCR-284 with a properly placed wire antenna, especially in the early morning and evenings on lower frequencies, mid-day on the higher end of its’ coverage. However tropical atmospherics and spectrum congestion would be significant issues.
SCR-284 in Burma Signal Corps Photo
Above: An SCR-284 with Merril’s Marauders in Myitkyina Burma 1944. Official US Army Signal Corps Photo
The US Army Center of Military History (CMH) website on Merril’s Marauders states that the SCR-284 was a “5-20 mile range” set. It also states that the AN/PRC-1 was “a lightweight, high-powered radio set having a normal range of from 200 to 2,000 miles”. (They both have a CW power output of 25-30 watts; the AN/PRC-1 also went up to 12 Mc versus 5.8 MC of the SCR-284. These higher frequencies provided the opportunity for “long range”.) The CMH document also states that the “long range radio” was difficult to use due to the requirement to crank the hand generator. Something wrong here.
The AN/PRC-1 is a suitcase radio primarily designed for Military Intelligence work. Built into a fiber suitcase with no other environmental protection it would not last long in a jungle – and it is only powered by 50/60 cps AC power, not a hand generator. The SCR-284 IS powered by a hand generator in the low power setting. At least one book quotes that exact Army CMH text and it is beginning to look like another case of “circular research” by authors not familiar with radio. They also had a modified SCR-177 but that is a whole other story. Additionally, they also had an HF set called the “V-100” but I cannot find any information on that set. More digging needed here.
See discussions in the Comments section below.
Below, a couple of shots of the SCR-284 “in the field”. Merrills Marauders, 1944. Photos by Bernard Hoffman. Dim watermarks indicate these photo’s appeared in Life Magazine. This first photo shows the whip antenna not installed in the IN-106A insulator. Likely they were using a wire, probably an inverted “L” or just a randomly deployed wire depending upon their tactical situation and availability of local supports. Some wires are draped over the insulator leading off into the bush. There appears to be an HS-30 headphone “Y” draped over the insulator.
Note the absence of weapons except for the likely K-Bar knife worn by the helmeted soldier. Also, there appears to be a PE-104 vibrator power supply under his right arm – this powers the SCR-284 receiver when using the hand-cranked generator. Without it, you need to have a BA-43 battery – which is preferred. Nice – if you can get one in Burma that still has any charge left in it. Foliage looks like bamboo, in-theatre, Burma. The soldier with the glasses is not cranking the GN-45 but the operator appears to be writing; so they are either in standby or just receiving off the BA-43 battery in the receiver. Judging by the sun angle, probably near mid-day.
So in the 3.8 – 5.8 Mc frequency band of the SCR-284 at that time of day in the jungle they were likely working someone in very close proximity or possibly a nearby aircraft. (At night it would have been capable of several-hundred mile ranges in that frequency band.) The T-17 microphone is on the operating shelf as is the mounted key. No M-209 cypher machine in sight although this unit was equipped with the M-209. That may be an M-209 printed white decryption tape trailing off the operating shelf in the foreground corner.
In the below photo, the radio Standby Switch indicates it is on the Low Power mode (appropriate for hand-cranked generator power) and the Main switch is in the Voice position. The T-17 microphone is lying on the operating table at the ready.
In this case they appear to be using the whip antenna as the lead-in wire seems to be connected. But I don’t see the radial ground wires. Maybe not always needed, a hassle to rig. “Good enough” may have been good enough for the task at hand; engineering design enhancements notwithstanding. This might be a Combat Team CP, working with SCR-536 Handy Talkie’s in the local area or working up to another SCR-284 up the food chain. Again, low power AM Voice on a vertical antenna in the daytime will not get you very far in the jungle.
Merrill’s Marauders were resupplied by air; the photo may be depicting them coordinating an airdrop on their position. Possibly waiting for the sound of an approaching C-47 before getting the Power Supply all exhausted. The mules don’t seem to be particularly concerned.
UPDATE*: As noted by Bob, a Merrill’s Marauders Burma veteran (in the Comments section below), the SCR-284 was only used for ground-air communications and was considered a “dog”. Not surprising with the weight, bulk and complexity of this non-waterproofed equipment when used in the jungle and transported by mules. They were also equipped with SCR-300 sets but apparently the C-47 resupply aircraft available did not have FM capability. Bob told me that he had rigged SCR-300 sets with wire antennas behind the pilot’s seats in the L4 – type Liaison aircraft and they worked well. He thought the SCR-536 (AKA BC-611) sets were pretty useless with their short range. Thanks for your inputs on this Bob! and thanks for your service!*** Above: Note the object behind the GN-45 generator in the above photo: Looks like a saddle from one of the “Motor Transport” units grazing nearby…Much better than humping (“rucking” for your Army guys) this gear! An interesting photo.
Why would they set up a big, heavy, valuable, essential radio in a clearing and not under the cover of trees? No enemy aircraft in the area? Obviously a hot day – why not in the shade at least. The near-vertical shadows indicate it is near noon in the tropics. Wearing a steel helmet on a hot day in the jungle indicates this is not a safe, administrative rear area setup. No such thing back then. Above 2 photos via Life Magazine.
SCR-284 in Burma
Above: Task Force MARS in Burma: The Assistant Power Supply is multi tasking at the Comm Center. Official US Army Photo.
SCR-284 at Batt Com Center N6CC
Above: The SCR-284 set up in the Battalion Comm Center at Camp Delta during less stressful times – the MVCC September 2011 rally and campout. A real favorite of the WWII vets who can still make it to the event. The kids really like cranking away as well – I usually have it tuned to the KSM transmitter up on the Pacific coast that transmits CW on Saturdays on 4350 Kc. Want to hear CW, you have to work for it. The GN-45 crank generator powers the PE-104 receiver power supply, lighting things up. Transmitting with it is a real workout – forcing all those electrons to do unnatural things.!
Future Radio Men: SCR-284
“Dad! Come here – this is cool!”
SCR-284 Fire Control Party Normandy
Above: Calling in Naval Gunfire with an SCR-284 from a shell hole in Normandy. The soldier on the right is one of the 17 Comanche Code Talkers of the 4th Signal Company, U.S. 4th Infantry Division. He is likely taking tactical calls-for-fires on his SCR-536 (AKA BC-611) Handy Talkie, relaying from a nearby infantry unit in-contact.
Note that he and the soldier in the foreground are armed with the M1 Carbine. The GN-45 generator “cranker” probably has a Carbine slung across his back as well. Also note the M1903 bolt action Springfield rifle in the background; an unusual weapon for a team like this. Contrary to the idiotic premise of the movie “Windtalkers”, the code talkers did not have “security” guards standing by ready to kill them to prevent their capture.
Here, the radio is placed on the ground without the legs – not needed here. There appears to be a spare BA-38 battery for the Handy Talkie laying on the radio’s operating table (dark, long rectangular object). The cluttered table may indicate the CW key is not in use – Voice mode possibly?
Those comms out to the ships on the “gun line” would have been numerically coded with the target coordinates and ammunition type requested for that target. No M-209 encryption machine is visible – they probably had one.
It appears the operator is writing in a message book, probably an M-210. He appears to be wearing headphones under his helmet – likely an HS-30; no speaker evident. Note the (five?) unused antenna sections in the carrying bag behind the operator. Either “spares” or they wanted to keep a low profile without a long whip antenna advertising “AIM HERE”. Official US Army Signal Corps Photo. Thanks guys…..We remember.
SCR-284 / PE-103 Dynamotor in action
Above, the SCR-284 also during less stressful times. Still works great after 70 years. Here, fairly complete with the PE-103 dynamotor and the internal PE-104 receiver power supply, incorrect CW key and headset. Note that I didn’t want to carry it very far from the Motor Transport Unit. On a favorite hilltop with the whip and T-17 mircophone, battery powered at 12 Volts. Using the big early ceramic whip antenna insulator – still looking for the proper J-48 CW key (that I can afford!)…
SCR-284 at LZ Ollie
Above: Playing with the SCR-284 at LZ Ollie. Working an SCR-536 Handy Talkie somewhere in the woods nearby this hilltop.
SCR-284 at the MVCC / MRCG event 2014
Above: My SCR-284 set up at the “Battalion Communications Center” display at the MVCC/MRCG event at Camp Delta. Everything here was operational and on-line – we made many short and long range contacts from here. I finally found an affordable J-48 key for the set, seen here. The counterpoise system had been connected over to the GRC-9 in this photo. It is an important component in the system – don’t leave home without it! The SCR-284 is always a hit with the visitors and especially the WWII / Korean War vets but also with kids who like to try cranking the generator.
Notes on powering the receiver without a PE-104: (6/22/16)
The 284 is a great radio, lots of history but they are somewhat unusual in the power supply department. They were designed to run on either 6 or 12 volts via the PE-103 dynamotor and PE-104 power supply. The power system “common” in the chassis is floating, not DC connected to the chassis as seen in almost all other radios. This permitted the installation in vehicles with either positive or negative ground systems. That causes some head scratching in trying to figure out how to power it with a battery for the receiver. Or an external homebrew AC power supply if necessary.
The receiver requires 1.4 VDC for the filaments, +90 VDC for the B+. Many people lash up some D Cells and ten 9 volt “transistor radio” batteries for the receiver, they last a long time. They just need to be connected to the battery plug pins as though they were the BA-43. Radionerds has the TM, manual and schematic which will show the pin assignments..
http://radionerds.com/index.php/SCR-284
That battery or the PE-104 provide those voltages from either 6 or 12 volts (there’s a switch) but they also provide -45 VDC which is required for the transmitter PA grid bias. If you just want to power the receiver for now, the -45 VDC is not needed, but it must be present if you will also be powering the transmitter as well. As in all work like this, be very careful when you wire it up – a buddy of mine accidentally put 90 volts on the filament pin. Killed all the RX tubes in his set….Instantly.
If you find a PE-104 it will probably have a bad vibrator (contact corrosion) but they can be disassembled and cleaned. The selenium rectifiers are also suspect, they can be replaced with silicon diodes (and probably series dropping resistors). Seventy year old capacitors are also always suspect.
The SCR-284 was used during the Korean war as available and as needed as a contingency. During WWII, it was being replaced by the SCR-694 (BC-1306 being the basic component). SCR-694’s were procured in 1944 and 1945 in quantities of 14,416 and 9316 sets respectively. There is no reference to any procurements of AN/GRC-9 sets through 1945 thus providing additional confirmation that the GRC-9 was not procured or available in WWII. Reference (74).
UPDATE: The BC-654 on 60 meters CW:
I set up the BC-654 on the 60 meter Channel 4 CW frequency of 5373 kc. Driving a 40 foot random wire in the trees from the Commo Bunker. Since this antenna presented a fairly high impedance to the transmitter, there was not much RF antenna current indicated but plenty of output nonetheless.
SCR-284 on 60 Meters CW
It worked well, getting into the KPH SDR receiver about 50 miles from here, mid-day, at an S-7 or so signal strength. Keying dynamics and drift stability were both acceptable on that frequency. I used a counter to set the frequency to mid-channel as required.
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For best results, make sure you have the receiver installed. And powered.
Grandpa – I can’t hear anything…
Photo credit Cowan Publishing Corp.
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Updated 2/15/2022: US Marines of a Tactical Air Control Party with the First Marine Division in combat at the Chosin Reservoir operating an AN/GRC-9 transmitter-receiver. Hand cranked generator, cold weather, […]