it's based on the Mark Weiss audio filters and Forrest Cook balanced
modulator matrix.
i haven't built this. though it should all work
i redid most of the filters to use common parts, and changed
some stuff on the 1496 per the motorola data book. the mpx filter was
also changed to roll off at 100khz instead of 57khz. this will prevent
any phase shifts in the upper sideband of the L-R signal.
Instructions
~~~~~~~~~~~~
- use 1% metal film resistors
- and polystyrene caps
- and HFQ eletrolytic caps
- and high Q, 5% inductors
- get the 38 Khz crystal from digi-key
- get the 12-100 pf caps from mouser
- national's LM833 = NE5532
- get the DG201 from www.jdr.com ($1.39) DONT use 4066
(MAX312CPE free samples also work)
- pilot and subcarrier must be in perfect phase for best stereo seperation,
and in a real system would be phased lock looped.
- carriet detect circuits are not needed if parts are limited, use LEDs on the
switches
