AWA CR6-B Communications Receiver

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General Description

The CR-6B was derived from the AWA CR-6 communications receiver. The CR-6B (AWA Type no 2C60600) was built for the then Department of Civil Aviation (Australia) to provide ground monitoring of in-flight HF aircraft communications, normally under crystal control, as well as provide the capacity to monitor the operation of the non-directional aircraft beacons in the 200 - 500 kc range.

The handbook dates from May, 1961

The receiver represents the end of the valve era and the circuit features approaches radically different from earlier receivers. The valve line up is:

The valve complement is:
6BY7 RF Amp	6BA6/6BA6/6AU6 Aperiodic IF Amp (100kc input)	Solid State Noise Limiter
6AJ8 1st Mixer/Osc(O/P 1.8 mc/s to Block Filter)	AM Detector - Solid State	6AU6 Crystal Calibrator 500kc
12AU7 Xtal Oscillator (6 xtal positions)	CW/SSB Detector 12AU7 Product Detector	6AU6 Audio Amplifier
6AJ8 2nd Mixer (1700 kc)	6AU6 Beat Frequency Oscillator	6AQ5 Audio Output (L/S & 600 ohm line output)

The power supply consists of a full wave bridge providing 150vdc for HT and 6.3v for heaters. A VR tube (OB2) provides power for the noise limiter and variable oscillator.

There are 6 wavebands : 0.2 - 0.54 Mc/s 2.0 - 5.0 M/cs 5.0 - 10 Mc/s 10 - 15 Mc/s 15 - 20 Mc/s 20 - 25 Mc/s

The CR-6B suffers from oscillator drift when using manual tuning. Crystal control solves this problem. Performance on the NDB band is not brilliant. This was not a problem for DCA as they only needed it to check performance of local beacons.

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