Actually, Robin, Joe Pursley (KF5MC) came up with the Paragon
mod by comparing an older with a newer Paragon. Here is what
he found:
On the Minor Loop Board:
"There was a thermister soldered across pins 2 and 3 of U5"
"R28 was paralleled with a like resistor."
"C29 was removed."
Joe measured the thermistor value as 30 ohms and found one that
was close in his junk box.
I suspect that this mod is some sort of temperature compensation for
loop gain. I have not put the mod in myself. As Joe and several
others said, the best fix is to resolder all of the connections of
both the major and minor loop boards. I had started out by
just resoldering connections in the VCO areas or those connections
that looked bad, but I ultimately had to resolder everything.
Also, in the course of poking around (literally), I found a couple of
microphonic components that would produce the garbled audio
if moved or wiggled. They are, on the Major Loop board:
T3 (Fixed by coating it with clear nail polish (and resoldering)
C29 (replaced with a tantalum capacitor)
Also, for good measure, I replaced the aluminum electrolytics
C5 and C3 on the Minor Loop baord with tantalum equivalents,
which I believe do a better filtering job and are more reliable
anyway.
So far, my Paragon is behaving itself, but I still have it under
observation, so I haven't buttoned it up yet.
73, Bob WB2VUF
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