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Old 29th May 2020, 8:10 am   #20
OscarFoxtrot
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Join Date: Apr 2011
Location: Edinburgh, UK.
Posts: 805
Default Re: Tandy/Realistic FM wireless intercoms

This is a mains programme distribution unit, from Public Address Handbook, Vivian Capel. Separate sender and receiver.

A two-stage modulator which modulates the collector current of the rf oscillator. Should be at about 100 kHz. There is no frequency stabilising. Applies the output to live and earth (not neutral) as this avoids the effect of heavy shunting loads in the circuit. (This dates from 1971 when RCDs were either unknown or certainly not in common use.)

A tuned circuit and diode detector in the receiver.

"All components are standard except the oscillator coils which were specially wound."
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