[Amps] Quiet Cooling

[Will Matney]

Paul,
Actually it's the best method and the same used in broadcast tubes. 
Vapor cooling is another way to go. I always pondered water cooling one 
but never looked into the cost. Plus I was always wondering what would 
happen if she sprang a leak. Theres a neat little cooler made by Bernard 
(mig welding guns) which is a table top arrangement. It has the pump, 
fan, reservoir, and radiator built in a smaller package enough for one 
500 amp gun (17,500 watts). However, that's not all that cools the gun, 
there's C02 or an Argon-C02 mixed gas flowing in it. It only uses about 
1/4" tubing for the connections though. I would be interested in the 
setup and how you did it as that's one thing I never did fool with.

For history, lets not forget the old Crosley broadcasting station here 
in Ohio, WLW (Voice of America).  She loafed along at 500 Kw (500,000) 
watts all day long. England heard the broadcasts (like the station was 
there) and the Royal Family would make requests. Canada actually 
complained about her shutting their broadcasting down. Yup she was a big 
one. Here's some info on her from Jim Hawkins; 
http://hawkins.pair.com/wlwbroch.html .That PA used 512 gallons per 
minute to cool her and had cooling ponds outside the building. Tours are 
available and if your ever here (Cincinnati), to go see it. In 1939, the 
FCC ordered the station to drop power down to 50 Kw. Keep in mind, this 
is an AM radio station. Now how would you like that for QRO? That's 
about like the old commercial, "When EF Hutton talks, everybody 
listens"! LOL =)

Will Matney

Paul Whatton wrote:

> Water cooling is very quiet! I converted my 23cms cavity amplifier 
> this summer (admittedly a small one) and wonder why I didn't do it 
> years ago. Thermal drift has all but vanished and the cooling is silent.
>
> Paul G4DCV
>
> Will Matney wrote:
>
>> Hal, and others,
>>
>> There may be a way of using baffles with an internal enclosed fan. 
>> Speaker cabinet construction uses some features where acoustic 
>> engineers design a majority of them in industry. That would be a good 
>> person to speak with if we could stir one up. Suppose a high output 
>> muffin fan were placed in an acoustic deadened enclosure using 
>> available sound deadening materials. There's some foam sheet 
>> available really cheap for this at Parts Express 
>> (http://www.partsexpress.com/). Another thought would be to make the 
>> amp chassis like large speaker and guitar amps and or speaker 
>> enclosures using the leather look vinyl, etc. I have to say, I have 
>> always wanted one built this way as they really look good compared to 
>> plain painted aluminum, or steel chassis. This way, any ugly 
>> enclosure could be made exceptionally good looking with exceptional 
>> sound deadening. A 1/4" plywood carcus with the black vinyl cover, 
>> black or chrome corner guards, black anodized face plate, white silk 
>> screening, would be the berries. A standard bright aluminum skinned 
>> chassis underneath for shielding would be all thats needed. Scuffs, 
>> etc on the aluminum or steel wouldn't matter. An example would be the 
>> Cobra 2000 11 meter transceiver. They had a plywood cover with a 
>> woodgrain veneer, which looked sharp, over a plated steel chassis. 
>> Even an amp with a good varnished plywood cover would make the 
>> aesthetics very good and deaden sound. If the air was routed around 
>> correctly, and the fan placed correctly, I think it would be a good 
>> bit what were wanting.
>>
>> Mounting the blower remotely has always been a good option to get rid 
>> of noise and is easy to do using clothes dryer or vacuum cleaner 
>> hose. This hose is pretty cheap and available from McMaster Carr and 
>> other vendors. On large amps, the exhaust can be routed out of the 
>> building via dryer hose and a dryer vent. I've done this myself on 
>> amp projects, one using a 4CX5000 back in 1988.
>>
>> Another insulation material that could be mounted around a fan, away 
>> from major heat would be foam board used in home insulation. This 
>> stuff is really cheap in 4" X 8" sheets. This would effectively 
>> deaden noise radiating from the fan itself. If the output air hit 
>> some baffling before coming out of the chassis, it too should die 
>> down to an acceptable level I would think. Anymore, you cant hardly 
>> here automobile engines run because of insulation under the hood and 
>> on the firewall. Open the hood, and you can then hear it.
>>
>> A good method of cooling in an amp would be blower cool the tubes, 
>> then use a fan to blow across the transformer, the power supply, then 
>> the tank circuit on its way out. One amp in particular, though 
>> illegal, did have a very good cooling scheme like this. The Kenrich 
>> Eagle 515 used a back mounted muffin fan blowing first over the 
>> control circuitry, then the transformer, through the driver stage, 
>> the the final stage, and out the side of the chassis. The air was 
>> routed by baffles made of aluminum sheet. It went through the chassis 
>> in the shape of a U. When running, it could barely be heard but you 
>> could easily feel the output from the fan at the vent hole in the 
>> side. If anyone here could take a look at a picture of one of these, 
>> you'll see what I'm speaking of. If interested, I could do a drawing 
>> of how this was and save it as a jpeg. The manufacturer was a Ham and 
>> was doing this back in the 70's until the very early 80's. This was a 
>> well thought out design and probably the best I've ever seen for 
>> these amps.
>>
>> The methods your mentioning in organs could certainly be used on a 
>> remote blower which could feed several pieces of equipment.
>>
>> Will Matney
>>
>>
>> Sirs,
>>
>> The thread about quiet cooling of amplifiers made me think back to
>> my college days when among studies of alcoholic consumption,
>> music appreciation and techniques for attracting YL's I studied
>> pipe organ construction and repair.
>>
>> The musicians do not want to hear the air blower mechanism when they're
>> keyboarding and neither does any audience or congregation.
>>
>> What pipe organ builders do is to isolate the blower in another room
>> and use a "wind-column" to supply the wind chests under the pipes
>> with pressurized air.
>>
>> Could not this technique be applied to amplifiers? Remove the noisy
>> blower from the shack and connect flexible hose to a clamped fitting
>> on any equipment needing cooling. A much beefier fan could be
>> employed than would fashionably fit on a rear apron, and a manifold 
>> system could be arranged so that more than one piece of
>> gear could benefit
>>
>> Hal
>> W4HBM
>>
>>
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