Yes, this is clearly a mid-1960s design, and undoubtedly was
Raytheon's offering for an SSB manpack set during the early
Vietnam war period. It was an interesting period from the
tactical radio viewpoint, with new, advanced SSB, synthesized
solid-state designs appearing, and this was one of them.
When Kennedy involved the U.S. in Vietnam, the Army's HF manpack
set was the obsolete AN/GRC-9, which was 1940s technology. The
Army's SSB manpack development program was the AN/PRC-62, begun at
RCA in 1962. The PRC-62 was highly advanced; 20W USB or CW, 2-30
MHz in 1 kHz steps, operating from 10-30V DC, and useable in
either manpack or vehicular configuration. By 1964, LBJ was
escalating the war, the complex PRC-62 wasn't ready, and the Army
started looking at alternatives. DARPA conducted a southeast asia
field trial of the available HF manpack radios including the
prototype AN/TRC-88 (SSB version of the crystal-controlled
TRC-77), the Hughes HC-162 prototype, and probably this Raytheon
prototype. They even tested a commercial Japanese SSB set
marketed to the maritime industry, which gives an idea of how
desperate they were.
After various modifications, the Hughes HC-162 was designated
AN/PRC-74, but was referred to as "the interim HF manpack", as it
was intended only to fill the gap until the more advanced PRC-62
entered service. The PRC-62 was field tested at Ft. Huachuca in
1966, and some sets were sent to Vietnam, but ultimately, the
radio never entered service--exactly why is lost to history. As
late as 1968 the PRC-74B was still called "the interim HF manpack"
and, although it wasn't what the Army really wanted, it did
provide satisfactory service, so around that time PRC-62
development was quietly terminated.
Some important technology came out of these prototype radios,
particularly in the area of frequency synthesis. The magnesium
battery technology developed for the PRC-62 ended up in the
PRC-77, and the PRC-62 battery box was later used on the PRC-70.
I restored a prototype PRC-62 and found it to be quite a good
radio. This Raytheon set, like the RCA PRC-62, is a forgotten
piece of tactical radio development history. Probably only a
handful were made, and it may be the only one of its type left.
Hopefully someone will analyze and test it, and let us know how
good a radio it actually is.
73,
John K9WT
Could it have been a competitor to the PRC-74?
B. Gentry, KA2IVY
On 7/22/25 4:09 PM, Nick England wrote:
Whazzit?2-11 mc AM/SSB/CW transceiver, 1965 vintage?, 12v batteryTransistor, Synthesized, 1 kc increments (1 mc master oscillator)
455kc Collins filters. Lots of double-balanced mixers.Raytheon logo on one circuit board but not elsewhere.
Some of the photos are just from trying to use the camera as a magnifying glass.It looks like the front panel ought to fold down, but connections to the LOAD control prevent that - I'm still trying to figure out how to get deeper and trace some connections.
I couldn't remove the cover atop the slug-tuned coils - I lifted and peeked and it looks like the 1mc bandswitch. I can't figure out that nearby module coupled to it by the chain and with leads from the LOAD switch.
Handset connector is MC10-14-6PN - a second connector was pulled and extender wires added.
A cable/BNC connector has been added which runs back to the 455kc IF module.The antenna connection has been bodged up a bit. The battery connector was replaced by a 3-wire terminal strip.
The 2N1899 output transistor is rated 125w dissipation.
It looks like there may be an internal switching p/s module (left rear of chassis)?
Please email info or leadsThanks
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