[Amps] Fan control

[Gary Smith]

Ian, 

Thanks for the suggestion. I've looked at a few of these on fleabay, 
now that you suggested a PWM fan controller for me to look at. I need 
to read up on these to see if they will fit what I'm looking for. 

Even with the Bose QC-15 headsets on, the noise from the fan is too 
much with the amp 18" away and the fan at full speed. Since I usually 
am not transmitting, lowering the fan speed and then raising it when 
the tubes start to get hot just makes sense.

73,

Gary
KA1J 

> eBay has a number of thermostatic controller boards for 12V
> computer-type fans using a thermistor sensor and pulse width modulation
> to vary the fan speed. Details vary, but typically the fan starts at low
> speed when the sensor reaches about 30degC and ramps up to full speed at
> 75degC or above.
> 
> Search ebay.com for   PWM fan controller. Typical price is under $10
> with free shipping from you-know-where.
> 
> The available designs vary as time goes by, and I've had good success
> with two different boards over the past year. One of the boards is used
> inside a transceiver covering 1.8-146MHz with no trace of RFI problems
> from the pulsed 12V supply to the fan.
> 
> 
> 73 from Ian GM3SEK
> 
> 
> >-----Original Message-----
> >From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Gary
> >Smith
> >Sent: 14 September 2016 15:19
> >To: amps at contesting.com
> >Subject: [Amps] Fan control
> >
> >I still haven't gotten round to putting in
> >a fan control into my old Alpha. There is
> >a wire resistor with slider that allows
> >changing the fan speed and I have it on
> >maximum RPM right now and the blower noise
> >is excessive when un-needed.
> >
> >I think if I had a thermostat with the
> >probe in the hot air duct and a 2nd slider
> >on the resistor, the fan could be set low
> >for normal resting & brief transmissions &
> >when the temp goes up, the fan could kick
> >in all the way.
> >
> >Has anyone done this and if so, is there
> >an inexpensive small thermostat you can
> >suggest which I can install inside the
> >control section of the amp to do this? I'd
> >be fine with running the cabling out the
> >back & into the duct, I'm running my
> >thermometer into the duct and it works
> >perfectly.
> >
> >Seems like a small digital/mechanical unit
> >with outputs to fire a SS relay would be
> >ideal. I've looked at what I could find at
> >the last two hamfests but no cigar. Yet.
> >
> >73,
> >
> >Gary
> >KA1J
> >
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