I think the 8877 with its oxyd cathode will getter via filament cooking.
That should be done before bringing it up that way
73
Peter
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
Behalf Of Carl
Sent: Donnerstag, 31. Juli 2008 18:37
To: w0jx@yahoo.com; klahaie@centricata.com
Cc: Amplifiers
Subject: Re: [Amps] 8877 tests
Filament cooking does very little for an 8877 and it almost always has to be
slowly brought up under current protected HV and bias. A bigger than normal
glitch resistor will provide additional protection. Ive used a 100 Ω 200W
wirewound in the past.
Spare tubes should be cycled in an amp yearly.
Carl
KM1H
----- Original Message -----
From: "Dennis W0JX" <w0jx@yahoo.com>
To: <klahaie@centricata.com>
Cc: "Amplifiers" <amps@contesting.com>
Sent: Thursday, July 31, 2008 11:51 AM
Subject: Re: [Amps] 8877 tests
If/when you build that amp be sure to put a glitch resistor in series
with the anode supply to the tube. Old 8877's can get gassy. I cooked my
Ebay 8877 for three days with only filament voltage and the blower on.
Also started it up with low voltage. Glad I had a glitch resistor
because I still got an arc over. After that, though, it settled down and
performs nicely.
Good Luck, Dennis W0JX/8
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