Radios................

[V40]

This might interest others who are collecting items from the Vietnam Era. What I have is some of the radios used during Vietnam. A small collection which would be about 1/9th of all the radios used there. Starting from the left to the right and going Clockwise we have the following:

1) The top radio here is called a AN/URC-68. This is one of the early type of Aircrew Survival Radios that all pilots were to wear in case of an "Ejection" from the plane. Elite unit(s) also used them, and yes even SOG wood wear them religiously on an "Across-The-Fence" scenario. Notice all of the dials and such. Can be a P.I.T.A to use.

2) Below that we have a helmet receiver called a "Helmet-Mounted AN/PRR-9 Receiver". I will go out and find a picture on the web of one being connected and used. This is a Receiver only.

3) We will skip the next picture in its entirely because it can confuse some others.

3a) These are two different flavors out of a possible 6-7 more radios of this type. However, we have here are two variants of the PRC-90's. The one on the left is a "PRC-90-0". These are both "Excellent" Survival Radios" that were still used on up through the 90's and considering that the left side version came out in 1968, still makes it an excellent choice among Pilots of that Vietnam War Era. The first one used is on the left side and it has all of the abilities that one could ask for in a survival radio. Again, these units were used by "Elite" units and SOG. The one on the right is a PRC-90-1. It has the "Morse code" removed. Also, above the two of those is a black-wire. This was found in the black plastic bags hanging off of each hand strap on the PRC-90's. One end of the wire has a 9volt battery hookup and the other end has a ear piece. This was all used in case you were shot down or are a member of SOG.

Note: The Survival radios were all used by the pilots of the Army, Navy, Air Force, and Marines in their each survival vests and seat kits with about four extra batteries. So the Pilot had one in his equipment along with an extra battery tied to the outside. You then will find another survival radio of the same sort as to what is on the vests along with usually two extra batteries and with one battery already installed in both radios. Redundancy was necessity back then. Therefore, SOG used the same Radios, Survival Vests and sometimes even the Pilots overalls, and other truly unimaginable ordnance and equipment added to SOG's equipment Connexes.

One other item to explain; Each survival radio had at least two different channels that were standard all of the time on each radio. These channels were: 243 Mhz (Also known as the Guard Channel) and the 282.0MHz. Some models could have different crystals added or deleted so that the Recon Team can have a Guard Frequency of 243 Mhz and different frequency's added as needed. SOG ALWAYS retained the Guard Channel for themselves and for the FAC of the day and for moonbeam (I believe this is the correct contact sign for the C-130 orbiting along Laos, and Cambodia). This special equipped Hercules had all kinds of directional devices, FLIR, side looking radar, and commo up the ying-yang! They were the only lifeline for SOG at night.




4) This is also another survival radio called a RT-60. Again SOG used it along with the pilots who were issued with it. SOG also used this too in their survival kits with an extra battery.

5) This is the infamous PRC-77. It replaced the PRC-25 later in the war. Although it was better than the old PRC-25, the Army


Will Continue tomorrow>>>>>

 

[V40]

delayed shipping them to Vietnam until May 1968. The reason being for the hold up was that the NSA needed time to correct the deficiencies, and there were allot, in the KY-38. The (PRC-25/77) in the KY-38 companion voice-security devices. From SOG's stance on these they used them for a short time and found the KY-38 along with the PRC-77 to be very heavy to say the least. Whether you were SOG, Mike Force's, LRRP's, Hatchet Forces, or an A-Team on some Fire support base, the weight was still too much for the average soldier to carry. And if you were on a aforementioned TEAM that required quietness for safety and to stay alive it was considered by those users to be a piece of junk and at the most, reliable half the time. SOG especially would not take it out on a mission. And since they answered "no" to the Pentagon they did not have to carry it at all because of the sensitive missions that they did.

Thus started the use of one day tablets that were used with a three letter designation to describe what happened that day (SITREP). Since they were used just once they could be destroyed by water or a very damp environment such as is found in the Laos and Cambodia Regions. The tablet would then be carried in a plastic wrapper from a PRC-25/77 battery to keep it dry.

Next is the answer for the Army's requirement for a "Walkies Talkie" type, short range communication between the platoon and their Squad Leaders. This system required the use of the AN/PRT-4 Walkies Talkie Transmitter only and the AN/PRR-9 receiver only. The bottom of photo one is a AN/PRR-9 helmet receiver. Also, in photo number 6 you just see the AN/PRT-4 transmitter. Unit cost was $1,100. SOG used this combination from what I understand, on a limited basis, an with somewhat succesfully.

The next picture includes the two different batteries that can be used in the PRC-25/77 I believe? The bottom left is a Lithium-Oxide battery and the top middle is a Magnesium battery which takes up the entire battery box. I own a PRC-77 which differed from the 25 in that the 25 used an old Vacuum tube for its transmition and recieving units. Whereby the 77 was/is completely solid state. The tan box on the lower right of the photo holds two batteries for the AN/PRT-4.

The last picture is the front of the of the first picture's top radio, the AN/URC-68.

This about it as far as the man-portable radios are concerned. If anybody wants to add anything to this, then by all means please do so or if I have made a mistake, again, please tell me. all of these errors on my part will be changed if I find in the books that it i true. Please, for any 4radio corrections, first PM me.

Thank you!

 

[Robert B.]

I can't believe it has taken me so long to see this, but here goes.

A very nice collection there! I thought I'd add some snaps of my own sets here.



The big telephone handset here is an AN/PRC-6 from 1954 masquarading as a later greek version, the PRC-6/E (I have one of those too, but not to hand). The PRC-6/E sets were selected older valve versions that were largely rebuilt in the 1980's by the Greek military with solid state one watt chassis. The only internal items retained were a multi-tag solder strip, the microphone and earphone elements and external controls. The inside of this set is original however and is based on miniature and subminiature valves (tubes in the US). It is fully functional and I operate it (via a ham radio licence) on 51 mhz. Power is supplied via some PP3 and C cell batteries connected to a french inverter supply (DY-29-A).
These inverters were built in the 1970's to power the french TR-PP-8, essentially a licence built 6 channel variant of the classic PRC-6. Indeed, this simple radio had a rich and varied history spanning the last months of the korean war through to service in Vietnam (1964-67, with some limited use up to '72) before being shipped to a NATO ally, prbably Greece. This set fortunately survived conversion. In addition variants were produced or used by Germany, Argentina and Israel in addition to Greece and france, there may be others. The last of these sets (the 6/E's) have only recently been retired and released from storage in Greece and are regularly for sale on e-bay (atleast two as I type this now).

Battery requires -4.5v bias, 1.5v filaments, 45 HT, 90v HT (transmit only). Power out: 200 - 350mW. Range is generally quoted as one mile but I have managed six with ease and nine miles at a stretch, albeit under ideal conditions as opposed to lying on my belly in deep vegetation under fire.

The middle set is an AN/PRT-4, same as yours. This one was built in 1964, so probably saw active service. It was reconditioned in 1989 and again in 1992. It is crystaled on both channels for 51 mhz and has an output of 510 mW High/ 206 mW low (according to its servicing sheet - I've never measured this). I run it off 18v (two PP3's in series hidden inside an original battery casing). It works well with the AN/PRC-6 and W.S.88-AFV (more on that later).

The set on the far right is a URC-4 distress radio for pilots after bail-out. This is an early british-built version by Thorn Electrical Industries, presumably for use by USAF forces in europe (I can find no evidence for it being used by the RAF). Without opening it up I think the internal components were dated 1954. It is rather unusual in that it entirely uses a line-up of british designed and produced valves (e.g. HIVAC XR-4) that are not entirely compatible with the US equivilents. They saw service during the early years of the vietnam conflict but were rapidly replaced by other distress sets like yours posted above. Their lifespan in non operational theatres was much longer. This set does work and I have tested its reception on 121.5 +243 mhz, but fortunately didn't hear anything. Transmit is untested for obvious reasons. It is hoped to one day get around to re-tuning it for the amateur 2 meter band around 144.5Mhz.

Output is a whopping 50mW! It receives AM voice and transmits AM voice, modulated Morse or a continuous tone.



The next set is a british Wireless Set 88 - A, built in 1947. These are 1/4 watt FM manpacks that were developed and field-trialed in 1945 but did not see standard use until 1947. They were the first FM squad radio sets and operated on 4 crystal channels between 38-42 mhz. They were designed to be inter-operable with the Wireless Set 31, a UK built copy of the famous wartime BC-1000. They saw active service in Korea and other conflicts until being phased out of active use in the late 1950's. Many went on (as this one did) to have a second life in cadet units until the drycell battery packs (one shown) became unavailable in the mid 70's. Hundreds were disposed of cheaply through surplus channels and brought by radio amatuers for conversion to the six or ten meter bands. This example was only released by a cadet unit clearing out its stores last year, although it has not been used since the late 70's.
It is hoped to get this one running on 10 meters at some point, I first need to find the matching headset.


The second WS88 shown is the WS88 A-AFV (along with my 2-meters set up), a standard A variant converted for use in military vehicles alongside the W.S.19 instalation. This particular set has no valves inside as it was heavily modified by an amateur for six meter band reception some time ago. A 70's solid state board is connected to the front controls and headphone sockets and it uses an internal 9v battery. This set is often used for demonstrations with the PRC-6 and PRT-4 on 51 Mhz.


The last set shown is a rather tired BC-611. It is missing its data plate (along with almost everything else) and hence I am unable to tell which variant it is or even if it is a post-war french example. I suspect not however as the crackle finish matches wartime US sets. This is evidently a long term restoration with an awful lot of parts to find, but I'd rather resurrect a war veteran than buy one. The fact i can't afford an unmolested example may also influence my decision.

Well, that just about rounds up my manpacks. All sets operated under licence (with the exception of the URC-4, which is currently an ornament). I thought I'd add this as a teaser: my college days with the british wartime R107, affectionately named 'Big Bertha'.



Robs