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DA/PRC-261 portable VHF FM transceiver

History

(from http://www.qsl.net/wb4tur/milt/feature/prclist.htm)

CPRC-26: Portable Canadian VHF/FM transceiver. Intended as a squad radio similar in purpose to the US PRC-6. Variant models of CPRC-26 exist I/E CPRC-26 (A-F), the only deference in these being the frequencies of the six channels supplied. The CPRC-26 could be carried in a variety of different manors i.e. it could be hand carried, worn on a standard pistol belt, shoulder carried with a canvas strap, or it's harness allowed it too be worn as a back-pack, under the arm, or on the chest offset to the right or left. In the mid 1950's the US acquired a quantity of CPRC-26's to be tested as possible replacements for the PRC-6.It was officially judged as "having no significant advantage". In fact the set had many advantages, including it's 6 channel capacity, ability to use an assortment of antennas & batteries, replacement of the battery did not require disassembly of the radio as it used a separate battery box, multiple carry options, smaller size & heavier construction, field serviceability with less logistic problems (the CPRC-26 uses plug in modules that are in large part interchangeable with those in the US & Canadian variants of the PRC-10). On the other hand, the US PRC-6 used discrete components few of which were interchangeable with anything else, It was a very ungainly radio to repair, align (it's numerous tuning coils are rather fragile) & use. The CPRC-26 was also adopted by Holland, who later improved it by conversion to solid state. It is possible that this version too was tested by the US. Ops 47-54mc, on any of 6 independently tuned channels, using the same xtals as the US PRC-6. RF power output approx 300mw. Requires 1.5v/850ma, 45v/8ma, 90v/30ma(trans), 1.5v/550ma, and 45v/12ma. 90v/3ma, -3v bias (rec), supplied by BA-289. Accessories include, H-5001 handset, H-5002 headphone, CTS-4 battery test set, CCX/CPRC-26 battery cable (for arctic use), Type 88 British antenna (in addition any of the common US short steel type antennas can be used), US type AT-339 homing antenna, CAT-3 long wire antenna, CCW-1 canvas bag, CTS-3 test set. Other known users include Australia and Britain (as the A-40).

DA/PRC-260: Portable VHF FM transceiver. This Danish radio set is outwardly identical to the Canadian or Danish CPRC-26, having only a slightly shorter battery box. Internally it has been converted to solid state, & operation is from 12vdc/125ma. Operational parameters & accessories are the same as for the CPRC-26. It is possible that the US Government obtained a small quantity of these radios for evaluation.

DA/PRC-261: This radio is identical to the DA/PRC-260 excepting for the addition of a two position bank switch which doubles it's original channel capacity of 6 to 12 channels. Power is derived from internal AA cells providing 15V DC. Built by N.V. Philips Telecommunicatie with known examples being produced Under License of A/S Bravour.

Here's more on the CPRC-26 and a bit on the PRC-261.

Three x PRC-261

I thought I had two of these but when I went looking I found three. Seems they multiply. I got the first two from Eldred ZS1DJ, the other one... Idunno.

Serials are 3210-63, 3798-64 and 3839-64. Two have been fitted with permanently wired-in handsets.

The PRC-261 has 12 channels arranged in two banks of six, or six banks of two... there are only six sets of tuned circuits, so the A bank and B bank crystals for each channel need to be relatively close in frequency.

Constuction is modular, with 12 modules, the smaller with one B9A plug, the larger with two.

One of the two sets with the wired-in handsets came to me with modules missing. Specifically, the AF amp, PA and Mic amp.

Telemit H-33 handset. This could have been the original handset for these radios, but based on being permanently wired-in (i.e. the plug didn't match the socket) I'd say they came from somewhere else.

Here's a scan of the schematic I got with the rigs. Final is a 2N1692 good for maybe a third of a watt if you're lucky.

The Wireless Set No 19 Group has the Technical Handbook for Operating and Maintenance - TH-327 -- but in Danish. It does have a very legible schematic so it's worth a bit of headscratching and maybe downloading a dictionary.

Crystals

The PRC-261 uses a single crystal per channel. The crystal is 11.5 MHz below the operating frequency. My three came with the following crystals / frequencies.

Crystal frequencyOperating Frequency
38.50050.000
38.70050.200
39.50051.000
39.70051.200
41.10052.600
41.30052.800

The first two frequencies don't conform to the bandplan, of course. But there are so few people on six in ZS land that I doubt anyone would notice.


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