Bob Kirkland wrote:
>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.
Tape over the anode-grid ceramic to avoid contaminating it, and then use
more aggressive solvents. For example, soak the anode cooler upside-down
in a pot of solvent, and then blast out the mess with an airline.
Don't worry too much about contaminating the ceramic base of the tube -
you can easily clean that later, using a toothbrush and more solvent.
One of the water-based aerosol foam cleaners for electronics is good for
removing the brown dust/tar mess from most other places inside the amp.
A whole amp will use at least one big can, and LOTS of kitchen towel.
Take care about high-voltage areas inside an amp, where you shouldn't
spray a water-based cleaner unless you're sure you can dry it off
again. Sometimes it helps to work on a small area at a time, spraying it
extra-heavily and using a ball of kitchen towel located to collect all
the runoff.
After the tubes, the insides of the blower will probably be the next
biggest single mess, so remove the blower and work on that separately.
Use a solvent-based switch cleaner on the bandswitches, meter switches
etc. In places where nicotine tar has deposited, it will form a
nonconducting film. This isn't so much trouble in amps, but in
low-voltage/current equipment with lots of switches - like transceivers
- it can be murder.
And having done all that, if you're a non-smoker you'll still be able to
smell it for years...
--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek
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