Power for this decoder board is derived from any conv10 to +12 volt
D.C rail within the customer’s host tuner. Incoming power is regulated to +8
volts D.C using one (MC78L08 equivalent) three-terminal IC chip mounted
directly on the decoder board. Note that the tuner supply rail must be able
to deliver up to continuous 20 milli-Amperes (mA)
–
(10mA typical for stereo
decoder, and 10mA maximum for driving the user’s stereo LED indicator).
Selecting a suitable host AM tuner or receiver
Not every FM stereo tuner can be converted to receive AM stereo
broadcasts. However, if you are careful when you examine the tuner’s
capabilities, the conversion should proceed, and successful results should be
achieved.
1. Vacuum-tube radios are unacceptable. You will undoubtedly experience
issues due to the high voltages and extreme operating temperatures involved.
2. Cheap pocket radios, clock radios, small table radios, portable radios,
and the like should not be used. They typically have narrow I.F bandwidths,
poor station sensitivity, and self-generated phase and frequency modulations
that can seriously degrade channel separation and increase distortion and noise
(C-QuAM system uses phase-related information, so your AM stereo decoder
is extremely sensitive to phase variations and phase modulation).
3. Manually-tuned tuners, whether variable capacitor or variable inductor
types, may cause audible microphonics when in stereo mode. Receivers with
self-contained speakers may also be subject to microphonics, due to the
speaker cone vibrations. Those vibrations may generate phase modulation
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