[Johnson] Viking Thunderbolt

[Steve H]

Anyone out there do neutralizing on their Thunderbolt?

The manual says to I guess throw a cw carrier on 20m
and I guess apply drive so you get 20mA of grid current
tuning up, I suppose into a dummy load with max power?

I decided to try the Kenwood way , so I installed a screen grid switch
so you could monitor output leakage with a wattmeter with no screen
voltage. With the plate voltage applied, I saw anywhere from 8-10W
leaking through by varying the drive on the 80m band.

It became tedious trying to move the neutralizing cap even through the hole
I drilled for access in the top cover so I opted to retune into a dummy load
and saw only 600w max from the linear, and the corner tube was glowing red,
the other didnt seem to be working much at all, so I guess that was about 
half power
and neutralizing was way off.

I set the cap to max capacitance, then backed off about 2 turns, and 
retried. Now the other
tube was glowing just like the other had, and I redipped and now could get 
1100W on the meter
via cw carrier.

A few more tests resulted in a strange problem, after I removed the drive 
signal, the plate current
remianed where it was for 1100w output and the tubes continued to glow. I 
had thought my TR
relay stuck, but I keyed and unkeyed it no problem, so I guess this was 
self-oscillaiton?

I went back and backed off another 2 turns on the neutralizing cap, and now 
I have not seen that problem.
So I am left to believe perhaps I was on the extreme edge since I was on max 
capacitance, and working my way
backwards.

Since I was on 80m, should I neutralize on all the bands up to 10m?

Steve Hearns
KA2PTE