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I got the 3n204 replaced, and put it all
back together,
and began to get some response. So I thought I
would
start trying the alignment procedure once
again. While
adjusting the agc pot to set the s-meter,
there was very
little change in level, and nowhere enough to
correctly cal
the s-meter.
After checking the schematic, I figured I
would check the
easiest things first, which in this case there is 4
diodes, 1n4148's
three of these had very high resistance, but
otherwise good.
I changed them out, re-check the agc level,
and now have almost
too much!!
At this point, I realized that as hacked-up
as this radio is, I really
should start at the begining.
I check the PS7, voltage, ripple, all was
great, couldn't be better.
I then go to the power regulator board. what
a mess!!!
I removed several diy mods, replaced caps
with ones of the correct values,
etc.
Now, all voltages and pb voltage adjustments
off this board are good, EXCEPT,
the neg 5v. I think there is a
couple of shorted windings on the small pcb
transformer, and about the best voltage I get
from it is about -3.4, but only when
the 10v pot is set to well over 10.75v, not
good.
The radio will begin to receive
with 10v set correctly, but I only have -3v, any lower
and the digtial stops, and no audio. and I
doubt the alignment will ever be correct at such a
low voltage.
back now to scratching my head, and
trying to figure out a way to fix, hopefully with re-winding
the transformer, or having to replace the
board.
Don
KB5GNH
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- [drakelist] tr7 update don
- Re: [drakelist] tr7 update Garey Barrell
- RE: [drakelist] tr7 update Ronald Baker
