I'm the new proud owner of a R-390A. (Some will say I'm a fool but
I had to follow my heart!) It's rackmount, which is great because
I've got rack space. I want to keep it well fed and ventilated.

At the moment, the rack has a 10" EG&G/Caravel Rotron fan in the top.
It moves a lot of air and generates a fair amount of noise. Not
bad in a computer room, but I want to hear the radio instead of the
fan.

I anticipate keeping the R-390A on more regularly than my other tube
radios (Heathkits etc.). Probably several hours a day.

In addition, the radio probably isn't as thermally stable as it could
be if
I'm sucking lotsa air through it. Someone might tell me that it's
bad to use a fan for some other reason.

Which way to go? Speed control on the fan to slow it down and keep
it quiet? No fan at all, because the R-390A was designed not to need
it? Some vastly more quiet and appropriate fan?

Tim. (KA0BTD)

If you elect to stay with fans, I had good luck with fans from
acoustiProducts. (vendor http://www.siliconacoustics.com). I used these
for an OR application, trying to surgeons happy. They really were quieter
that :Standard" fans.

Hear a few of the other manufacturers of reduced noise fans. IMHO, you
really need to look carefully as the word quiet is very subjective.

Specifications for Panaflo and for Cormair Rotron Whispers are from
www.comairrotron.com

Specifications for NMB fans are from www.nmbtech.com

Specifications for JMC fans are from www.jmcproducts.com (good ANSI specs)

Noiseblocker fan specs from www.Blacknoise.de, but good luck finding the
fans in North America.

Verax fan specs from shop.erfrier.net (German). I'm not sure if they are
available in North America

Don


wrote in message
oups.com...
I'm the new proud owner of a R-390A. (Some will say I'm a fool but
I had to follow my heart!) It's rackmount, which is great because
I've got rack space. I want to keep it well fed and ventilated.

At the moment, the rack has a 10" EG&G/Caravel Rotron fan in the top.
It moves a lot of air and generates a fair amount of noise. Not
bad in a computer room, but I want to hear the radio instead of the
fan.

I anticipate keeping the R-390A on more regularly than my other tube
radios (Heathkits etc.). Probably several hours a day.

In addition, the radio probably isn't as thermally stable as it could
be if
I'm sucking lotsa air through it. Someone might tell me that it's
bad to use a fan for some other reason.

Which way to go? Speed control on the fan to slow it down and keep
it quiet? No fan at all, because the R-390A was designed not to need
it? Some vastly more quiet and appropriate fan?

Tim. (KA0BTD)

My experience is that ordinary fans run at reduced voltage are a great
way to achieve quiet operation. The muffin fans in HP 264x CRT
terminals ran virtually silent because HP operated them at 1/2 their
nameplate voltage. I cool my old Heathkit boatanchor rig with a 12 V
brushless DC muffin fan that is silent because I run it at 6 V. If your
rack has 2 fans an easy solution is to simply wire them in series so
they run at 1/2 voltage.

John

wrote:
I'm the new proud owner of a R-390A. (Some will say I'm a fool but
I had to follow my heart!) It's rackmount, which is great because
I've got rack space. I want to keep it well fed and ventilated.

At the moment, the rack has a 10" EG&G/Caravel Rotron fan in the top.
It moves a lot of air and generates a fair amount of noise. Not
bad in a computer room, but I want to hear the radio instead of the
fan.

I anticipate keeping the R-390A on more regularly than my other tube
radios (Heathkits etc.). Probably several hours a day.

In addition, the radio probably isn't as thermally stable as it could
be if
I'm sucking lotsa air through it. Someone might tell me that it's
bad to use a fan for some other reason.

Which way to go? Speed control on the fan to slow it down and keep
it quiet? No fan at all, because the R-390A was designed not to need
it? Some vastly more quiet and appropriate fan?

Tim. (KA0BTD)

wrote in message
oups.com...
I'm the new proud owner of a R-390A. (Some will say I'm a fool but
I had to follow my heart!) It's rackmount, which is great because
I've got rack space. I want to keep it well fed and ventilated.

I'll agree with those some others. I used the mil equivalent of the
R-390 when I was in the army in the late '60s in Germany, and I was
stuck in a radio van on the back of a deuce-and-a-half. One consolation
was that it didn't need much heating in the winter. I think the one I
used was made by Motorola (or were they called Galvin?).

At the moment, the rack has a 10" EG&G/Caravel Rotron fan in the top.
It moves a lot of air and generates a fair amount of noise. Not
bad in a computer room, but I want to hear the radio instead of the
fan.

I anticipate keeping the R-390A on more regularly than my other tube
radios (Heathkits etc.). Probably several hours a day.

The radio site was right next to the 100kW diesel generators that ran
24/7, just to run all those toobs and air conditioning they needed to
cool them. Nothing like a diesel generator to keep you awake all the
time. The guy that bunked in my cubicle used to bring his (Dave Clark)
earmuffs to bed with him, and sleep with them on. I never could figure
out how he did that. ;-)

In addition, the radio probably isn't as thermally stable as it could
be if
I'm sucking lotsa air through it. Someone might tell me that it's
bad to use a fan for some other reason.

Use a filter to keep out the dust and reduce the noise.

Which way to go? Speed control on the fan to slow it down and keep
it quiet? No fan at all, because the R-390A was designed not to need
it? Some vastly more quiet and appropriate fan?

Puff up your chest with pride and show off your R-390 boatanchor a
couple times a year to your ham buddies, and the rest of the time use a
Sony ICF whatever they are or similar general coverage receiver. ;-)

Mount a panel with a speaker in it in the rack, and connect the Sony to
it, and your friends will never know. You'll have a lot lower electric
bill this summer. :-))

Tim. (KA0BTD)

In article .com,
wrote:

At the moment, the rack has a 10" EG&G/Caravel Rotron fan in the top.
It moves a lot of air and generates a fair amount of noise. Not
bad in a computer room, but I want to hear the radio instead of the
fan.

So add a power resistor and drop the voltage until there is around 80V on
the fan. It will move less air, but it will be very quiet.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."