MC85.2

  In summary, (2) and (3) are
necessary but (1) is a MUST.  These mods cured completely all
the RF feedback problems that one can have with the MC-85.
Before closing the microphone's base cover, I added a few
more mods.  I hope they are clear from the modified scheme
and the notes.  (Notice that all these mods can be done
without having to remove the printed circuit board.)  A
similar thing happened wtih the PC1-A phone patch...started
because of a "serious" problem and ended with extra "very
helpful" mods.
The "serious" problem was that no matter how loud I put the
RX gain control, there was never enough audio to the
telephone line, and not only that, the audio was distorted!
(See IRI of April, 1987, Issue No. 64, Page K64, where C.M.
Luchessa WN6O, suffers a similar problem and asks:  "Any
remedial information will be appreciated".)  The problem was
solved by changing D5 and D6 (originally they were clipping
the audio at 0.7 volts).  I made the change by putting 3
silicon diodes on each leg, so now the clipping is done above
2 volts, and not at 0.7 volts,  R11 was changed from 27 to 10
ohms.  Again, before closing the patch's cover, I added a few
more mods.

continued in file mc85.1