Hi All,
I have a 2nd hand 8877 based 144 Mhz amp, built like a rock. Has worked
fine for over a year, then bang. I saw a flash and of course the fuse did
its job. The tube in it was maybe 20 years old.
It took out the shunt( resistor and diode) in the Grid and Meter which I
replaced. I figure I would replace the tube since I had a newer used tube.
I " burned" it in for about 18 hours with the filament and fan running and
another 6 hours with the HV on, just for good luck.
I keyed it and slowly brought the power up, worked fine at 5 W and at 10W
in I measured 230W on the bird meter and it flashed again, fuse again. I
replaced the fuse and powered it up and again at 10 Watts showing 230W, but
the metering was gone and I looked through the vent screen and saw it arcing
intermittently at the age of the fins, above the Anode strap that goes
around it.
I am looking for advise. Easy to fix the meter shunts, but is it a problem
with the tube(s), the anode strap is as tight as it goes.... any guesses.
73s
Les
W2LPL
Thanks
Les
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