If I recall, they have the QRO brand of amps set up this way, or I
seen one being modified I can't remember which. All they did was
mount a button type thermostat near the tube. Seems to me though they
used a single speed blower and used a resistor in series with the
line lead. The thermostat simply shorted out the resistor when it go
hot enough to close.
If it were me, I'd mount a small heatsink on the thermostat to catch
the hot air transfering it to the metal end of the thermostat. Maybe
make one from thin copper sheet (valley copper). One for a small
power transistor mounted on the metal end of the button would do it
and mount either near or in the heated air flow of the tube. You
would want a N/O type contact on the thermostat. You can buy these at
Granger for practically nothing along with the blower. The resistor
was a power resistor, maybe 25 watt, but I can't remember the value,
maybe 50 ohms or less.
Best,
Will
--- In ham_amplifiers@..., Tony King - W4ZT <w4zt-
060920@...> wrote:
R L Measures wrote:
On Oct 30, 2006, at 11:08 AM, zerobeat40 wrote:
Forget the link to the datasheet:
The only thing I have against the YC-156 is the noise...damn,
they're
loud, if you're wanting to run power and keep 'em cool.
One advantage of an 8171 is that a quiet 1700rpm blower will cool
one
VFB on SSB.
You can get a 1500 RPM blower from Dayton that will cool the YC-156/
179
and not be loud. They've got a nice two speed blower that'll do
even
better if you sense the cooling air temp and switch the speed ;)
73, Tony W4ZT
