[Johnson] "Viking II C-C" Modulation Saga...

[Diane Swynar]

Hi Everyone,

My thanks to all those kind fellows who took the toime to drop me notes re.
possible cures for the modulation problem I'm having with the Johnson
Viking II C-C transmitter I recently acquired...

The problem is STILL there, & frankly---for now, anyway!---I'm TOTALLY
vexxed. On CW, it's a super rig---on AM, though, it's a different story. As
soon as I crank up the mic gain & speak into it, the audio system
just "takes off"---modulator current goes to an excess well above 100+ ma.,
the audio just emits a loud buzz, the 807's glow purple, & the RF output
goes down. Cranking the mic gain right down to zero causes the feedback to
stop (or whatever else it might be).

Curiously, with just ONE 807 in the circuit, it does NOT "take off"---but
the audio is less than crystal clear. I've patched in a replacement
modulation transformer---no change. I've now tried my THIRD audio driver
transformer---same deal. The resistances & voltages in the complete audio
chain seem to measure up to snuff---and no modifications to the original
circuitry, either, that I can see. I even swapped plate connectors on the
807's, as was suggested by two previous e-mails---no dice...

These tests were all run into a 100-watt dummy load light bulb, with a non-
amplified D-104 microphone.

Could the problem possibly be in the RF stage being modulated? (NEVER had
that happen before, but who knows...). I tried running the rig with just
one 6146---no change as to the feedback. This whole thing really has me
feeling quite stupid, as I've built a 2x6AQ5 plate modulator (for a 2E26
final), a 2x245 Heising modulator (for a 245 final), & a 2x805 modulator
(for a 2x813 final) in the past, with NO hardships whatever...serves me
right, I guess, for breaking away from homebrewing!

Anyway. if any of you reading this have any experience with these otherwise
beautiful beasts from Waseca, I sure would LOVE to hear from you! Many
thanks, & my very

~73!~ Eddy VE3CUI - VE3XZ