Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Don -
Your -5.0V supply is "normal" at about -3.3 to -3.4V. That is what
they all run. This voltage is only used to back bias the diodes in the
IF filter switches, and seems to be adequate for that service.
73, Garey - K4OAH
Atlanta
Drake C-Line Service Manual
<http://www.k4oah.com>
don wrote:
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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