AR8 Receiver

AR8 Receiver

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A good article on this receiver appeared in HRSA Radio Waves for July 1999.

General Description

The AR8 receiver was built by AWA at Ashfield, Sydney, Australia during WW2. They were part of the AR8/AT5 aircraft MF/HF system.

The receivers were unique in design, having two front ends (MF and HF) which were switched into a common IF channel. (Note: Non standard IF Frequency 755kc.) This feature enabled two frequencies to be rapidly selected. For example, the MF tuner could be tuned to an NDB or broadcast station for DF purposes while the HF unit was set to a communication channel.

The sets were supplied with loop antennas for direction finding on the MF bands. The audio amplifier in the receiver was also utilized as an intercom amplifier that could drive five pairs of service headphones in parallel.

Technical Data

Reception modes were:
MF: 140 - 2000 kHz, CW, MCW, R/T, Aural DF and Sense
HF: 2000 - 20,000 kHz, CW,MCW and R/T

Sensitivity: 6mw audio output -
Below 9.5Mc Not more than 3uv input
Above 9.5Mc Not more than 10uv input

The valve complement is:
V1 6U7G 1st IF AmpV5 6J7G Audio OutputV103 6J5G HF Oscillator
V2 6A8G Beat OscV6 6X5 Limiter DiodeV201 6U7G MF RF Amp
V3 6U7G 2nd IF AmpV101 6U7G HF RF AmpV202 6A8G MF Converter
V4 6G8G Det/AF AmpV102 6A8G HF Converter

The limiter diode provided protection from the transmit signal and on some sets V103 6J5 was replaced with a 6V6 due to stock shortages.

Power Requirements:

The station could be configured for 12 or 24v operation. HT was supplied by a dynamotor during aircraft or portable operation, supplying 250vdc for the receiver. A mains supply, Type "S", to run the complete station was also available. It was very heavy.

The sets were popular with amateurs as very little work was required to put them on the air. The usual approach was to re-wire the filaments to 6.3v and build a standard type power supply to operate them. Some went to the extent of changing the output valve to a 6V6.

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Illustrations of the set

Identification labels coil box label coil box

View of the interior TOP - MF section to right and BOTTOM - MF to left (unit front at top in each case) . interior top view interior bottom view

View of back coil boxes

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© Ian O'Toole, 2009. Page created: 27/03/05 Last updated: 3/12/2009