I bought a couple of 80mm 115 volt AC fans and wired them in series, so
they are a little quieter - one hangs behind my principal transceiver and
helps me keep it cool, while the other sits on top of the amplifier. I
have had a problem with filaments melting out of their pins on this amp,
and the fan seems to help considerably, as did my recent swapping of grid
and filament springs in the sockets so as to get a bit better filament
connections.
73, Pete N4ZR
At 12:02 PM 2/14/2008, schuetzen wrote:
>Pete Smith wrote:
>>I don't know offhand what the L4 uses as its cooling blower, but my
>>SB-220 has a large fan (rather than a squirrel-cage blower) that is
>>mounted in the back of the cabinet and blows directly on the tubes. What
>>I did was to place a small "muffin fan" - like the ones in computer power
>>supplies - directly above the tubes on the upper cabinet. It operates as
>>you suggest, sucking air from the area around the tubes, and I have found
>>it definitely helps keep the tubes cool.
>>73, Pete N4ZR
>
>good idea Pete, what do you power it with?? I have about 15 fans of all
>sizes but they ran off the tower's three color wire leads from the
>PS. have no idea what the VAC was they were running on. maybe about 5v?
>
>so, your idea has me very curious on a couple of different aspects. I
>really believe that like all things with filaments in them, the cooler you
>can keep them, the longer they will last. I doubt that they would like
>zero degrees F. but... certainly keeping them at or close to room temp
>would not be bad if it could be done.<G>
>
>thanks
>chas, K5DAM
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