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Hi group..
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I have a 450S which has served me very well for ~30
years now. Long ago, I jumpered the resistors which formed part of the BCB,
effectively removing the attenuator. It was fine for years like that, but a few
months back I noticed a drop in BCB sensitivity.
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All other bands are fine...
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I checked everything I could, replaced the jumpers
and verified the ckt, to no avail.
I checked the control line for that?band at
the 74LS245 and found what I thought was the problem, so this morning I replaced
that IC.
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It didn't solve the problem. The only other thing I
can think of is that one of the 2 RLS135 diodes for that band might be flaky so
I checked them as diodes and they test fine.
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Is it possible that these diodes might operate fine
for DC but not for RF...?
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I think I'll replace those two diodes and check
again, but this has me a little stumped...
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73...Jordan VE6ZT
