[Johnson] Valiant VFO

[WQ9E at btsnetworks.net]

Doug,

With the symptom you describe I believe a dirty wiper on the tuning capacitor is the most likely culprit.  Any poor connection in the Valiant could cause this but I would start with cleaning the wipers on the tuning capacitor.  Access is not fun but you should be able to get there through the side sufficiently to address the wipers.

The W8JI described instability is largely from RF developed when actually transmitting so it isn't the culprit of these large random jumps while in standby.

Rodger WQ9E

-------- Original Message --------
> From: Douglas Rowlett <douglas.rowlett at gmail.com>
> Sent: Sunday, March 16, 2014 9:00 PM
> To: "johnson at mailman.qth.net" <johnson at mailman.qth.net>
> Subject: [Johnson] Valiant VFO
> 
> VFO was working fine on my Viking Valiant, but recently began exhibiting strange behavior. When first powered up, it acts normally, but after 5 minutes or so, attempting to adjust the frequency with the VFO knob causes the transmitter to jump to a random frequency somewhere in the band. As long as I don't touch the tuning knob, transmitter is stable and works normally. Touch that dial to zero beat, though, and away she goes. So, before I tear into this thing, any sage advice on where to start looking? Could it be as simple as a bad tube? Bad capacitor? Cold solder joint? Any advice to point me in the right direction so I don't spend hours in frustration will be appreciated.
> 
> Also, what's the best way into the VFO? Through the top, the side?
> 
> Doug, WB5IRI
> 
> Sent from my iPad.
> 
> Sent from my iPad.
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