[Johnson] Johnson Viking II Audio Mod Question

[Gary Schafer]

Check the meter shunts first. They have a reputation for changing value.

73
Gary  K4FMX

> -----Original Message-----
> From: johnson-bounces at mailman.qth.net [mailto:johnson-
> bounces at mailman.qth.net] On Behalf Of Freeberg, Scott (STP)
> Sent: Wednesday, July 11, 2007 11:44 AM
> To: johnson at mailman.qth.net
> Subject: RE: [Johnson] Johnson Viking II Audio Mod Question
> 
> My thanks to all the folks who replied on and off the list to my Viking II
> audio mod question.  Several folks provided audio mods to see if any of
> those matched, and several suggested I check other Johnson preamplifer
> circuits.  Bingo.  It's the Ranger preamplifier!   I'm beginning to wonder
> if the Viking I/II has the highest number of audio modification schemes of
> any transmitter :>
> 
> I started puttering with the modification last night. I was curious to
> know if the modulator iron was good.  I cleared up at least one short in
> the preamp mess and got it working on AM.
> 
> I need to poke around the clamper tonight.  The resting modulator current
> with the gain turned all the way down was almost 200 ma instead of the
> stated 80 ma.  I think that is dependent on the settings of the big power
> resistor under the chassis.  I'll check that tonight.
> 
> I'm still thinking of restoring the preamp back to original and starting
> from there.
> 
> Thanks again for all the advice and help offered!
> 
> 73, Scott WA9WFA