[AMRadio] Question for GK500 owners

[B Farrell]

I'm having trouble with my Globe King 500B, which previously functioned
properly.

Now, the initial tune up process is per the manual, and with the exciter
set to VFO Operate and closing the Transmit switch, the plate current dips
to around 160 mA adjusting the Final Plate Tuning cap. But advancing the
Ant. Loading cap I'm unable to increase plate current more than a few
milliamps, and regardless how much Ant. Loading is advance the current is
well under 200 mA and RF output is a little over 100 watts. This occurs on
80 and 40 meters. On 20 meters, when I close the Transmit switch, I can dip
plate current to 200 mA but it cannot be increased above that. I have not
tried other bands. Switching the fixed Ant. Coupling caps has little impact
on the plate current for each band I've tested. There seems to be
sufficient drive.

I have swapped the 6146 drive tube and the 4-250 final tube with no change.
I have checked the resistors and fixed caps associated with the drive and
final tubes, and plate voltages at the drive and final tubes is close to
what WRL specified. As far as I can determine, the switches and relays are
functioning properly. I have tightened every ground point I can see and the
tube socket connections appear intact. I reheated a few solder connections
that looked as if they needed it.

Have you experienced anything like this with your GK500? Were you able to
determine the cause?

73,
Brad K4RT