DX-100 causes a couple seconds worth of pops in receiver as the high voltage decays after letting up on the PTT button. Installed bypass caps around clamper that Johnson Viking Valiant uses; better, but still there. Any ideas? Ed.
Hi Ed,
I've experienced this problem many times, especially with voltages above 2KV. It is usually a bleed off path that bypasses the filter cap bleeder path. It can be so many things, like leaky filter caps, corona off sharp points, a terminal or lead that is too close to ground, etc.
It may even be related to parasitics or other instabilities that act up only when the HV is reduced. Try loading the grid of suspected tubes to be sure. Also, unplug tubes to divide and conquer from the rest of the circuit.
As a test, make the room totally black dark and look closely at the various parts as it pops. A big mirror behind the rig can help to see more angles at once. You may see a faint spark. Also, use an insulated pick up loop that goes to an AM receiver via a coax to sniff around for the loudest pop. This will often expose the culprit. Be careful with HV.
Also, as it pops, use an insulated stick (like a fiberglass rod) to push and pull parts. Often the popping will change character as the guilty part is moved.
Tighten down HV connections, look for corroded connections and re-solder connections in a shotgun approach.
It could also be a transformer winding that is breaking down, so prod that area and sniff around.
It's a matter of detective work. You will find it.
Tom, K1JJ
