[Boatanchors] HW-32 TX instability

[Gary Schafer]

Check for good grounds on the shields. Also the neutralization wire.

73
Gary  K4FMX

> -----Original Message-----
> From: boatanchors-bounces at mailman.qth.net [mailto:boatanchors-
> bounces at mailman.qth.net] On Behalf Of Ian Wilson
> Sent: Tuesday, March 23, 2010 11:33 AM
> To: boatanchors at mailman.qth.net
> Subject: [Boatanchors] HW-32 TX instability
> 
> I recently acquired a HW-32 20m monobander. Originally I was using too
> high
> LV+ (didn't
> realize the tap in the HP-23 was set to 'high'). Attempts to tune showed
> either no output
> or 100W of self-oscillation as the Final Tune control was varied. I am
> using
> a 50 ohm
> load (and have checked that this is connected to the PA output when the
> relay is in the TX
> position).
> 
> Lowering the LV+ to something more reasonable (around 250V) tamed the
> oscillation, but
> the Tune function doesn't work. I know about the Drive Level adjustment
> (and
> the Carrier Null
> balance control). Increasing the LV+ somewhat moves the PA closer to
> instability (e.g.
> inserting some audio causes the PA to start oscillating).
> 
> With the lower LV+, I see some output
> 
> I am going to disconnect the HV and remove the finals so I can work on
> this,
> but does
> anyone recognize these symptoms and/or have suggestions? I plan to
> replace
> the bypass
> capacitors around the driver and PA tubes.
> 
> 73, ian K3IMW
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