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R-744A

R-744A VHF Surveillance Receiver

General Notes

This small receiver was made by Arvin Industries for the US army during the early 1960s. Its dimensions are about 15 x 6 x 7 inches. Coverage is from 20 - 100MHz in one continuous range and it will receive AM, FM and CW modes. It uses sub-miniature pentodes types 6611 x 7 and 6612 x 3. Each of the 3 x IF stages, the calibration and BFO oscillators, AM detector and audio stage are separately housed in 8 small cylindrical cans about 2" high and 3/4" in diameter with a B9A tube base. The set is operated either by internal batteries or an external 24v vehicle power supply. There is no internal speaker, necessitating the use of headphones.

A variation seen is the R744(XE-3) made by Mallory, which doesn't have a bandspread knob. These sets were also used by the Australian Army, where the Contract Number under the makers name has been blacked out. There is also supposed to be a similar set covering 100 - 200 MHz. These sets were designed as surveillance receivers having continuously variable tuning to overcome the drawback that most field military sets were restricted to FM mode with only pre-set fixed frequencies at say 100kHz separation. The R744 was used in Vietnam and possibly other fields.

Very little information seems to be available on the internet about this receiver so I have posted a copy of the schematics in djvu format from the manual TM5825-203-20. I can supply a scanned copy of most of the full manual which is some 2.5Mb in DJVU format.


r744a ID plate

Collectability

These sets are very scarce in Australia and rarely come onto the market and even seem to be rare in the US and elsewhere judging by the lack of information on the internet. Here they would be very collectable and in working order probably a useful receiver. Their attraction for collectors would be helped by their functionality and small size in comparison with most military receivers. Only low serial numbers have been seen. The two earliest sets, including this one, have R-744A/PRR as ID and have S/N 12 and 16 whilst the later models, with the PRR suffix removed, have S/N 22, 59 and 60. I think it likely that sequence numbering is within a US contract and not across the full range of sets built.


Current Condition

This particular set, S/N 16, is unfortunately in poor internal condition as a result of being stored in a hot, damp environment for several years while presumably being opened up. In particular the tuning mechanism was siezed up but after months of shelf life with oil, freed itself up. The outside has been cleaned up and the case, apart from the front, repainted. It is therefore in reasonable cosmetic condition.


Some Internal Views

Top and bottom (plug-in modules can be seen on the right) r744a interior 1 r744a interior 2

Rear and case interior with 24v power supply r744a interior 3 r744a case interior

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Count since 28/6/07.
Page maintained by Simon Buxton VK2UA Created: 25/05/05 Updated: 24/11/2009