The tube is likely OK but the hardware needs a good examination and
cleaning...all the way from the tube to the N connector and dont dismiss
relays or coax.
Is this being tested on a dummy load?
Carl
KM1H
----- Original Message -----
From: "Les" <Listwa@comcast.net>
To: <amps@contesting.com>
Sent: Wednesday, November 23, 2011 4:21 PM
Subject: [Amps] Arcing 8877
> 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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