SCR-284 Radio Set

UPDATED 5/20/2024.

  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.

Here’s a shot of an SCR-284 with a Jeep bolted to it – ready to head Downrange aboard a C-47.

SCR-284 headed downrange. Library of Congress photo.

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
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. “Stuff happens.” 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.

Below is another interesting shot of an SCR-284 operated aboard ship.  From an Eimac employee newsletter dated June 1945.  Thanks Paul!

SCR-284 aboard ship

Note the wool sox, gloves, flotation belt and wood deck.  The Standby and Main switches are set for Low Power, Voice.  It’s the only photo I have seen of an SCR-284 being used aboard a ship although I don’t think that was particularly unusual at times during amphibious Ops.

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
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..

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.


For best results, make sure you have the receiver installed.  And powered.

Grandpa – I can’t hear anything…

Photo credit Cowan Publishing Corp.