[Boatanchors] Valiant Troubleshooting Question

[Gary Schafer]

The first thing I would look for is a bad loading capacitor on the tank
output. Look for a bad band switch or auxiliary loading switch contact.
It sounds like the final is loaded too heavy.
When you reduce the drive way down the screen clamp circuit comes into play
and reduces the screen voltage.

An easy way to check is to place a T connector at the output. Antenna or
dummy load to one side and a large variable (broadcast type) on the other
side of the T to ground. This will give you an extra range of loading
capacitor to see what happens.

Also could be your antenna went haywire. Try a dummy load first.

73
Gary  K4FMX

> -----Original Message-----
> From: Boatanchors [mailto:boatanchors-bounces at mailman.qth.net] On Behalf
> Of Whitebear1122
> Sent: Tuesday, December 30, 2014 3:30 PM
> To: boatanchors; johnson at mailman.qth.net
> Subject: [Boatanchors] 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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