late last year I purchased a Ameritron 811-H amp. First amp I have had in
years. Back in January i posted on this list my problem that I had blown a grid
resistor on the back right side tube. With the help of this list i learn much
and replaced the resistor after i also found what I had assumed to be the total
reason for the blown resistor. The tube in that socket had a visible defect
where the top spring like wires actually had blown loose and cold be shook up
and down with light shaking. Anyway replaced the tube with a set of Taylor
select (4 matched) from RF Parts. That was in January and all has been
perfect.. not an arc not a pop and tuned fine. I kept the 3 "good" tubes and
tossed the obvious bad tube.
Well now to the point of this email. Last week I came in to do a little ham
radio.. switched on the radio and then as always switched on the amp. POW! arc
and glow. Same resistor same tube. I pulled cover replaced the resistor and
replaced the tube with one of the original "good" tubes I had. Amp is back to
working perfect.
Any ideas? The last fix lasted 7 months.. all perfect. Both times the problem
occurred at switch on. opr mode in standby no RF load just when the switch
power was turned on. I did re-check the tube that appeared bad (no physical
defects seen) and proved that the tube has an internal short. (blew the
replaced resistor) .. anyway re-replaced the resistor and put the older "good"
tube back in and all is just fine... right now...
Question is.. does this sound like a tube problem an amp problem or both??
I do have a 3rd party soft start nit that my amp is plugged into and the amp is
wired for 240 v
Any suggestions?
Thanks for nay and all help...
D Pipes
dpipes@earthlink.net
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