[Johnson] Valiant Troubleshooting Question

[Evan Rolek via Johnson]

Scott and Fellow Boatanchor Enthusiasts,


While I can't speak with authority for all Valiants, I do know from experience that the electrolytics, if original, are problematic and need to be replaced.  While you're at it, checking the leakage of the line voltage bypass caps is a good idea too.  Mine had enough leakage to blow a 10 amp fuse!  I digress.


One thing I would do is check the meter shunts in the Valiant; two of them are basically a short length of nichrome wire and are known problem areas.  I replaced mine due to inaccurate and/or unstable grid current readings.  I used 1% resistor and they work fine.



Please keep the group informed of your progress.



73,




Evan, K9SQG




-----Original Message-----
From: Whitebear1122 <whitebear1122 at comcast.net>
To: boatanchors <boatanchors at mailman.qth.net>; johnson <johnson at mailman.qth.net>
Sent: Tue, Dec 30, 2014 4:30 pm
Subject: [Johnson] Valiant Troubleshooting Question


	Last night I tuned up on 80m for one of those delightful bitter cold winter 
night QSO's.  I haven't used the Valiant for a while.  With the meter in the 
Grid position I peaked the Exciter as usual, and then used the Drive control to 
set the grid current to around 7 ma.  At 7 ma, the Drive pot is normally around 
the 9 o'clock position.  The plate current was pegging the meter for all Aux 
Coupling positions, power output was nearly 200 watts so I know those 6146's are 
going nuclear.  I had to back off the exciter to get the plate current and power 
output back to normal.  At that point there is no Grid current reading on the 
meter.  If I peak the Exciter, then I have to back off the Drive control to 0.5 
(in-between dot 0 and dot 1) to get the plate current back to around 300 ma, 
again with no Grid current showing on the meter but getting 100 watts output.  

I can't imagine that a neutralization issue would do this on 80 meters.  10 
meters maybe  but I wouldn't think it would show up on 80m.  

I went to 20m and it seemed to tune up normally, although the Drive control was 
in the 3 O'clock position to get 7 ma Grid current.   I expect to crank the 
drive control up on the higher bands so that doesn't concern me.  

I'll have to open her up and look around but first has anyone experienced this 
sort of oddball operation or suggest a starting point?

Full disclosure:  I haven't recapped the electrolytic or paper caps yet.

Thanks, 73, Scott WA9WFA
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