WJ-8709 HF Receiver

Watkins-Johnson WJ-8709 HF Receiver

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General Description

The WJ - 8709 is a half rack width receiver of comparatively modern design. It has had wide use in the armed forces and is believed to have been manufactured from 1982 - 1988.

The receiver is a solid state double conversion superheterodyne. The new price for this receiver is $5,700 U.S. Second hand disposal units are currently advertised in the U.S. for $2,400 U.S.

Technical Data

The receiver tunes across 5kHz - 30MHz with a digital display. It is capable of AM/FM/CW/MCW/USB/LSB operation. Selectivity is 16/5/3.1/.3 kHz, -3db. Stability is 6x10 -8 per day. Sensitivity is less than .4 uv 16dB (S+N)/N CW.

The IF rejection is >80 dB, 3rd Order Int. +20 dBm. Antenna input is 50 ohms and audio output is 200 mw @ 600 ohms.

The receiver is of modular type construction. There are 5 tuning speeds. AGC is selectable Fast/Slow/Off. The tuning meter can be switched from RF input to Audio output.

The BFO frequency can be varied 8kHz in either direction in 10 Hz steps, using decadic BCD thumbwheel switches.

These receivers are designed for 115/220v 48-410 cycle operation. A circuit board insert in the rear of the receiver is used to select the appropriate operational voltage. Reference to the motherboard interface wiring diagram on the reverse of this page will enable owners to bypass the circuit board selector and hard wire for 240v.

These receivers are very easy to use and perform more like valve receivers than the crop of solid state receivers that are generally obtainable.

These are highly complex pieces of equipment and they can develop some quite trying faults.

The receivers are ideal for general monitoring and the frequency display is extremely accurate.

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© Ian O'Toole, 2009. Page created: 28/04/03 Last updated: 11/12/2009