Al,
> If you don't mind, could you briefly describe your cooling system?
A bucket under the desk, holding some 20 liters of water. A small
submersible AC powered pump in the bucket, the kind sold in home
improvement stores for decorative indoor fountains. Plain half-inch
garden hose up to the amp, and back down. The cool blocks are made from
copper sheet, soldered together. The shape is like a small finned
heatsink with a cover on the back, and two end covers with hose nipples
in them. The base plate is 5mm thick, the fins are 1mm. The whole thing
is quite small, as there is no point in making it larger, because the
thermal resistance along the copper basically disconnects any more
remote fin area. And there is a flow switch, that simply shuts down the
power supply if the flow falls below a certain value.
20 liters of water can store enough heat to last comfortably through an
afternoon of hamming, and overnight the bucket cools down almost to room
temperature. To work a 48 hour contest, some sort of heat exchanger with
fan would be needed, or the water would need to be replaced every
several hours.
The bucket has a cover on it, to keep out contamination, and keep
moisture in.
I'm using plain tap water, but my tap water comes from a well, has no
chlorine in it, and some slimy forms of life tend to grow in it, and
need to be flushed out from time to time.
> Is it tap water through the heatsink straight to the sewer
That would be dangerous! Tap water is usually colder than the room, and
very often it will be colder than the dew point inside the room. Flow
tap water straight from the tap to your amp, and you could easily get
condensation on your electronics. That can cause some fireworks.
Even my bucket system would pose some risk of condensation, if the
absolute humidity in the room can go up fast, for example if you live in
Florida, keep the room airconditioned, so that the bucket is cool, and
then suddenly you open windows and let in the hot and humid air from
outside. But I don't live in Florida! My house has very even
temperature, the relative humidity is never above 70%, and that gives me
enough safety margin against condensation.
As you can see, water cooling does have some quirks.
Manfred.
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