[Johnson] Viking 1 tuning

[Carl]

I use a V-I fairly often and its very predictable however I went completely 
thru it. All paper caps, electrolytics and any out of tolerance resistors 
were replaced. Tube pins wire brushed and then a very tiny drop of DeOxit on 
each pin and inserted in the socket several times.

Check all grounds; tighten hardware on kit built and be sure factory built 
rivets are making contact with the ground lugs and chassis.....both are 
common problems in all Johnsons.

A tiny drop of DeOxit on switch rotors also can help, rotate several times.

Next step is to check socket voltages and get out the scope if it still 
doesnt work.

Carl
KM1H


----- Original Message ----- 
From: "John King" <k5pgw at yahoo.com>
To: <johnson at mailman.qth.net>
Sent: Sunday, October 21, 2012 7:19 PM
Subject: [Johnson] Viking 1 tuning


I am having real trouble getting the exciter stages of my Viking 1 to tune 
as they should they were tuning up and providing drive to the final, but 
then the exciter stage stopped tuning as it should in the OSC, Buffer,Drive 
and Grid readings.
I have replaced the 6AU6, and 6AQ5 tubes with no improved results. I also 
changed the 6AL5 bias rectifier.

I am extremely frustrated by the malfunctioning exciter section. I have four 
other transmitters on the bench awaiting parts and finishing the Viking 1.

I had the Viking pumping out slightly over 100 watts and then the problem 
popped up. I replaced the audio driver transformer.

My conclusion is that the exciter stages in the Viking 1 are just very 
unstable and the instructions in the manual don't help me very much. Has 
anyone had a lot of first hand experience with the Viking 1 tuning and 
experienced the on again off again functioning of those stages. If so, I 
will greatly appreciate your assistance. The only tuning control that shows 
changes in tuning is the drive control. The oscillator and buffer controls 
make no difference in tuning. The Viking 1 is a simple transmitter but it is 
frustrating me. Thanks and 73, John, K5PGW
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