I like Ron's suggestion of external
mounting. If you put carpeting inside the
enclosure, you'll deaden the sound even
more.
What I did with the Alpha 77 which has a
user selectable speed via a wire resistor
& wiper, is to place a normally closed
thermal switch (125F) in the exhaust and
run the speed at lowest at all times it's
idling or little use. When I'm repeatedly
transmitting & the exhaust temp rises to
125, the switch closes and it jumps the
fan connection to maximum. When I stop,
the fan returns to it's slow setting at
124F.
I wear Bose Noise cancelling headsets and
even at high speed, the fan is almost
invisible.
OTOH, I've thought about removing the
squirrel cage, removing power to the motor
and attaching an adequate fan remotely,
the whoosh of full flow would not be as
bad as the internal squirrel cage next to
my head.
Something like this:
https://www.zenhydro.com/ipower-8-inch-inl
ine-fan-770-cfm.html
Of course one would want to compare
exhaust temps to be sure the external fan
was doing the job. They do have speed
controllers, not sure about the RFI
aspect.
I always liked quiet. I had a desktop
computer with a loud fan that I used for
recording. The hard drive and fan
interfered with the recording so I water
cooled all the parts with fans. Ran tygon
tubing to an already quiet Iwaki water
pump in a sound muffled enclosure at the
diagonal side of the room, no fan needed.
By the time the water got back it was room
temperature. Used two SSD for hard drives
and the only sound was the fan in the PS.
I had an oversized PS and it never ran at
anything but slow speed. Dead quiet...
73,
Gary
KA1J
> I have acquired a Henry 2K Classic X (domestic model) amplifier. It
> uses a pair of 3-500Z's with chimneys. The very loud Dayton blower is
> driving me nuts. The Dayton blower is a model 2C915A, 3020 RPM, 230
> volts and 140 CFM. This same blower is used when the larger Plate
> transformer of the Export model is installed. I suspect that this
> blower is much larger than required when operating at 1500 watts on CW
> or SSB.
>
> The standard blower in the 2K Classic was a Redmond 80239, 110vac
> unit. I cannot find the specs but I suspect it was around 90 CFM.
>
> I have researched several articles on about using a pair of 3-500Z's
> and the reference material shows a need for about 13 cfm per tube or
> 26 cfm total. Likewise, a 3-1000Z requires 4 cfm. I am aware that back
> pressure requirements play into this also.
>
> I read somewhere that it is possible to slow down a blower during
> standby periods by using a "split-capacitor" motor. Perhaps I have the
> phraseology wrong, but what I would like to do is have a blower slow
> down in speed significantly during listening periods and come up to
> speed during TX. I operate mostly CW, little SSB, and do not use
> break-in/QSK so I could switch relays to do this.
>
> My other alternative is to install a smaller blower and risk
> shortening tube life. I do not contest very much nor operate
> continuous modes such as RTTY and FT8 at full power.
>
> Your ideas are welcome!
>
> 73, Dennis W0JX
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
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