John:
Several years ago I ran a single 3CX100 in a cavity for 1296. The tube
was/is fitted with a water cooling device.
On the recommendation of "someone", I used mineral oil instead of water.
The theory was that mineral oil was less of a conductor than water, and had
better heat transfer capabilities.
All seemed to work well with that system, but, due to my location, I soon
gave up on 1296.
I've had thoughts recently about putting the 1296 system back on the air,
since there appears to be a few more stations about that I might work.
What are your thoughts regarding the use of mineral oil versus water?
73, Barrie, W7ALW
----- Original Message -----
From: "John T. M. Lyles" <jtml@lanl.gov>
To: <amps@contesting.com>
Sent: Wednesday, October 29, 2003 10:31 AM
Subject: [Amps] H2O cooled tubes
> To build a heat exchanger you can make some quick calculations to see
> what sort of heating you are dealing with.
>
> You will be dumping the plate dissipation, some filament power and
> some drive power (probably low) into heating water, and assume the
> worst case like it is mistuned at low efficiency. Then the
> temperature rise and flow are related by :
>
> 0.2648 x delta T x flow = Power in kW
> Using a mix of units, pardon me Europeans, where Delta T is in
> degrees C and Flow is in Gallons Per minute.
>
> You can then determine what sort of flow to expect through your
> transmission cooler or heater core, by hooking up your hose or pump,
> and pouring the outlet into a gallon bucket. With this sort of flow
> (assume some losses in the elbows and tubing), you will heat the
> water a given rise in temp over the outlet water.
>
> This all assumes that you have the heat removal capacity in your
> exchanger, a big fan outside, or a larger thermal mass at the other
> side of it. If the outlet temp rises over time, even with the fan
> running, then realize that your tube will run hotter too.
>
> Never boil water in the anode of a water cooled tube, unless it is
> specially designed for that, such as a vapor phase, multiphase,
> hypervapotron or whatever the manufacturer calls it.
>
> As for HV rating on the hoses, try to keep DC leakage current under
> one mA, or you may slowly eat away your pipe fittings where the HV
> bridges them across the water. Use Deionized water and take a reading
> on conductivity if you have a meter. You can calculate the hose
> diameter, and assume it is a resistor of that diameter with the
> conductivity per cm. You can determine how long the gap in the hoses
> needs to be for a given current. Smaller hoses give higher R, which
> is an advantage. Then the flow is lower of course. Then the Delta T
> is higher. All is a trade off.
>
> Try to use Teflon, polypropylene, silicone, or other low carbon
> hoses. PVC water pipe will work too, but keep it out of RF E fields.
>
> 73
> John
> K5PRO
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>
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