[Amps] Water cooled amp question

[Karl-Arne Markström]

As far as I know ethylene glycol as automotive anti-freeze dates from the mid-20's
when the "Prestolite" anti-freeze mixture was first marketed.

It is believed that the high-enthalpy and high-boiling point properties were known before, and glycol used as a 
liquid coolant for aircraft engines in the same time period.

If very high speed from a piston-engine powered aircraft was needed, a last resort could be
to use almost pure ethylene glycol as a coolant, and flying the aircraft with the cooling flaps
closed to reduce aerodynamic drag. A well known example was the 1939 world speed record
of  755,11 km/h set by Cpt. Fritz Wendel in a Messerschmitt Bf-109R special aircraft. 
It was reported that the engine was red-hot and almost ruined after the record flight.

My own experience from liquid-cooled "amps" come from the HF 1 kW SSA1000 and VHF/UHF 1 kW PA204
solid-state units, both built in the 80's by  ITT-Standard Radio in Sweden. 

They are intended to use Fluorinert as coolant, but as it is very expensive and has an enerving tendency to escape 
through even very minute leaks, the amateur users I know of use a 50-50 mixture of distilled water and glycol. 

As a water-glycol mixture has about twice the enthalpy as Fluorinert, the amplifier 
runs cooler for a given coolant flow as a side effect. 

The reason for using Fluorinert, according to the manufacturer, is that it can be stored in the cooling
system almost indefinitely without the risk of leaving any residues that can block the cooling channels or the pump.

73/

Karl-Arne
SM0AOM




----- Original Message ----- 
From: "Will Matney" <craxd1 at ezwv.com>
To: <amps at contesting.com>
Sent: Saturday, March 05, 2005 2:53 PM
Subject: Re: [Amps] Water cooled amp question


> Didn't think it went back that far. However, that Dupont plant has been there ever since dirt too. The 1940's was a guess but the more I remember, seems like that actually fired up back during WWI maybe or before as the town of Dupont is an old one. Along the Kanawaha river which goes through Charleston, WV. and dumps into the Ohio river, is where "chemical valley" sprang up. During the Civil War, places like Nitro, WV. sprang up making explosives and there all along that river. South Charleston was the home of Union Carbide, and we all remember Baupal India. Forgive the spelling on Baupal. Every 1-2 miles up there are large chemical plants and where a lot of the ordinance plants once were. The Kanawaha dumps out in the Ohio river about 40 miles above my house. Then, the Ohio is a stones throw away (be fishing in it in 10 minutes). That's the very reason nobody can eat any fish out of the rivers here. This has me curious now, I'll have to do some history work.
> 
> Will
> 
> *********** REPLY SEPARATOR ***********
> 
> On 3/5/05 at 8:34 AM G3rzp at aol.com wrote:
> Glycol/water mixtures were in use as antifreeze in aircraft cooling systems well prior to WW2. Examples were (are?) Spitfires and Hurricanes, among others.
> 
> 73
> 
> Peter G3RZP
> 
> 
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