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RECEPTION SET No. 1 (AUST.)

Sketch from Provisional Handbook

The Reception Set No.1 (Aust.) was a special communications receiver designed for interception reception in special Wireless Sections and for general communications within and above Corps. on CW and MCW telegraphy (W/T), and Radio Telephony (R/T). It covered a frequency range of 138 to 410 Kc/s (2174 to 731 metres) and 495 Kc/s to 25 Mc/s (606 to 12 metres) using 6 plug in coils to cover the range..

NOTE that the Reception Set No.1 (Aust.) was adapted from the Kingsley Radio KCR/11 that was used by the RAAF as the AR7.

A separate power supply was provided which allowed the receiver to operate from either 230-240v ac, from mains supply or a petrol generator, or from 12v dc provided by two 6 volt 150 ah. secondary batteries. The current consumption on ac was 0.32 amps at 230v. On dc it was 4.75 amps. The Power Supply had a 3 position switch on the front: 12VDC - OFF - 230VAC.

The IF was 455 Kc/s. The selectivity with the crystal filter off was:

                                                   At ± 6 Kc/s off resonance             --            20 db down
                                                   At ± 12 Kc/s off resonance            --            40 db down
                                                   At ± 18 Kc/s off resonance            --            60 db down

 The receiver used the following valves:
                                                V1            6U7G                 1st RF Amplifier
                                                V1B         6U7G                  2nd RF Amplifier
                                                V2A         6K8G                 Mixer - Oscillator
                                                V1C         6U7G                 1st IF Amplifier
                                                V1D         6U7G                 2nd IF Amplifier
                                                V3A         6G8G                 2nd Detector - AVC AF Amplifier
                                                V4A         6C8G                 BFO and Meter
                                                V5A         6V6G                 AF Output
                                                V6A         6X5GT               Half Wave Rectifier
                                                V6B         6X5GT               Half Wave Rectifier
                                                V1B1A                               Vibrator (Rectifier KRC11)

The manual notes that if either the 6U7G or 6K8G valves were replaced, the set should be returned to the ordnance workshops for realignment.

The aerial was arranged to accept either a doublet or a single wire and earth. At the rear of the case there was a compartment covered by a sliding lid. Inside the compartment were terminals marked A1, A2 and E. A1 and A2 were used with a doublet whilst a vertical aerial would be connected to A1 with an earth connected to E and A2 jumpered to E.

The tuning was accomplished by a large vernier dial as used on the HRO, AR7 and AMR100/101 style of receiver, driving a 4 gang capacitor.

The IF frequency was 455 Kc and the set had a Crystal filter.

FROM SKETCH OF No.1 IN PROVISIONAL MANUAL

The front panel controls were as follows - from top left:

SIGNAL "S" METER.

TONE CONTROL

MAIN TUNING

NOISE LIMITER

On the second row:

BFO

AVC/BFO SWITCH. A toggle switch that switched off the AVC and applied the BFO signal when switched to BFO.

"S" METER ADJUST to set the "S" meter to zero.

SELECTIVITY used when the crystal filer was in circuit.

CRYSTAL IN-OUT. A toggle switch marked IN-OUT.

PHASING. Used to adjust the phasing of the crystal when in circuit.

On the bottom row:

RF GAIN with PHONES No.1 SOCKET below. If headphones were plugged in the speaker was muted.

COIL BOX RECEPTACLE

AUDIO GAIN. In the anti-clockwise OFF position the set was on STAND BY. The HT was switched off but filament voltage remained applied to the valves. PHONES No.2 SOCKET below, which did not mute the speaker..

The construction of the set was identical to the AR7, with a sheetmetal chassis, reinforced by spotwelded gussets. The whole was copper plated for low electrical resistance and then cadmium plated for corrosion resistance. The Power supply was similarly fabricated. The 3 position switch on the Power Supply is the same as for the AR7, a 19" rack mount version..

The Reception Set No.1 Power Supply.
(courtesy of Chris Gill)

The No.1 set differed from the AR7 in that it was fitted into a drip proof metal case with compartments either side to hold the spare 4 coil boxes. (The set was issued with 6 coils, A to F. With one in the receiver and two either side in the compartments, where was no. 6 stored?) A sheet metal lid enclosed the set and coil compartments, with clips to hold it in place. The lid carried the headphones. As detailed above, the connections for speaker, 600 line and aerial connections were made in a compartment set into the rear of the case, and protected by a sliding metal cover. Flying leads connected between the terminal block and the set itself. There was a hole to allow the power lead socket to plug  directly onto the power plug on the rear of the receiver. The set could be withdrawn part way from the case to replace valves but to remove it completely, firstly screws holding the rear panel of the case had to be removed to free that panel, then the wires could be disconnected.

The case and lid of the No.1 were painted Khaki green No.3. However, there are reports of some being painted black and others are silver like the RAAF AR7.

Spare valves, fuses etc were carried in a Case, Valve and Receiver, No.2.

All the components of the Reception Set No.1 were allocated Army part numbers and nomenclature such  as "ZAA337, Condensers Variable, No.27 (Aust.)", etc.

References.
Provisional Pamphlet, Reception Set , No. 1 (Aust.) Also called Provisional Handbook. Reception Set No.1 (Aust.) 23 Dec. 1942.

Please note, this article is copyrighted.

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