[Amps] Need info on 8874's

[George & Marijke Guerin]

Hi Bob,

I guess I would call or e-mail Eimac and see what they recommend for a
cleaner.  I am sure you can find them if you do a Google search.

As to the date codes, I believe the first part is a plant code.  The tubes
were made in 1982, maybe the 89th and 99th production days?  Most everyone
else including Eimac on the 8877 uses year and week

The ceramics have Beryllium Oxide so be careful when scrubbing not to abrade
them.  The hazards sheet is big on the danger of dust or fumes from BeO.
Several posts on this reflector have warned people to wash hands thoroughly
after handling ceramic amplifier tubes.  I would guess that wearing
dishwashing gloves would be a good idea if trying to clean the tubes.

After cleaning and drying the tubes I would also do the following:
1.    put them in a warm oven - 170deg F for a while to make absolutely sure
they are dry.
2.    put them in the amp with the HV connector from the transformer
disconnected for an hour or more and let them cook with only air and
filament and control voltages.  That warning appears on some of the
commercial VHF amplifier data sheets for initial start up.  Make sure the
amp is disconnected from the AC mains and there is no residual HV when
opening up the amp.

73 & Good luck,    George    K8GG

----- Original Message -----
From: "Bob Kirkland" <w5pvr at i2k.net>
To: <amps at contesting.com>
Sent: Sunday, August 17, 2003 11:25 AM
Subject: [Amps] Need info on 8874's


> Recently bought an old Alpha PA-76, a 2 holer using 8874's. Anyone know
the
> Eimac date codes, these are marked E6QD 8289 and E6QD8299. Also the amp is
> full of nicotene and it is up inside the tubes fins. Have to get it out or
> the tubes won't cool properly soap and water no help inside the fins.
Maybe
> 409 would work but would it hurt the tubes ceramics, conductive?, ect.
> Bob, w5pvr at I2k.net
>
>
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