>I recently purchased one of these amps and just brought it home yesterday.
>This morning when I took it out to the ham shack, it slipped out of my hand
>and dropped onto the operating table. Everything seemed physically intact
>but when I try to load the amp with about fifty watts drive the plate cap
>starts to arc. I don't know yet but may need to replace the cap or other
If the Tune capacitor's plates are not bent from being dropped, the
arcing may be due to an intermittent instability problem around 100MHz.
You can check this out by placing a wavemeter near the Tune C. To find
out where to set the wavemeter, pull the mains plug, couple a dipmeter
the the hv dc blocking C. You should find a sharp dip. Read the freq.
and set the wavemeter accordingly. If and when the Tune C arcs, you
should see a large indication on the wavemeter. // Another way to check
this out is with a vhf field strength meter/spike ant. like you would
use to check out a 2m handytalky. If the vhf FS meter pegs out when the
Tune C arcs, chances are you have a vhf oscillation present.
>does anyone on this list know where I can locate parts for it?
Maybe you don't need replacement parts. Maybe you need lower vhf Q
parasite suppressors, Kevin?. Doing so would reduce the vhf
amplification at the anode circuit resonance by about one half.
- later -
R. L. Measures, 805-386-3734, AG6K
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