In my h/b amplifier I use ex military DOD-006 tubes .... These have a
thermostatic switch mounted at the tube base and are wired to shut things
down if the base exceeds (if I remember correctly) 150C. This would be
relatively easy to do on many tubes, and avoids the HV problems.
Alternatively, it should be fairly simple to fit a thermistor in the airflow
from the anodes without getting too close to the HV.
73 Roger
VE3ZI
(For those that may wonder, the DOD-006 is a version of the 7213, but with
heavy leads coming out to a base. They were very cheap. I understand that
the tubes were removed from a jammer transmitter which always struck me as
being rather appropriate!)
>From: Vic Rosenthal <rakefet@rakefet.com>
>To: Amps reflector <amps@contesting.com>
>Subject: Re: [AMPS] AL-1200 Blower
To: <amps@contesting.com>
>Date: Wed, 06 Dec 2000 11:01:25 -0800
>
>
>"Brakob, Hans" wrote:
> >
> > The exhaust is vented just like most other amps, via
> > grille-work directly above the tube chimney. The
> > cooling seems perfectly adequate (I run mostly CW),
> > but would be nice to be able to quiet that fan down
> > a little. Since the fan is variable speed (albeit
> > "variable by moving a wire to one of four taps")
> > maybe someone has figured out an automatic switching
> > system based on internal temperature?
>
>With a solid-state amp, it's easy to mount a thermostat on the heatsink.
>With
>tubes, it's more complicated...how about a thermostat clamped to the tube
>anode
>cooler? Isolation from the HV would be interesting. You'd also have to
>make
>sure that everything else that needs cooling (seals, tank coil, etc.) would
>be
>taken care of.
>
>73,
>Vic, K2VCO
>Fresno CA
>
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