Get out your old dog eared copies of care an feeding. The online version has
dumped
the parts about Nukiyamas theory of boiling water. You will notice they
depict the chart
and graphs for steam from 100-1000 deg C. Peak eff for vapour phase
cooling is at 130 deg C
and not 100 deg C.
If you read carefully, vapour phase cooling is not all its cracked up to be.
Read the fine print
in the eimac book. Forced air cooling is capable of 50 watts per sq CM of
internal anode area
of a tube. Vapour phase is good for just 135 watts per sq CM. And water
is good for 1000 watts
per sq CM. Water is still way more capable of removing loads of heat vs
vapour phase. And the
colder it is, the better it gets. Crank up the flow rate, and it gets even
better.
Why do the transistors have to have an insulator between em and the heat sink
anyway. Why
not just mount them directly to the heatsink. Then use stand offs to float
the heat sink
above any chassis. I used to do that with zener diodes in GG amps, worked
good. That’s
cuz I was living out in the bush back in the 80s..and had no proper insulator
at the time.
The ultimate heatsink for SS would be a solid block of copper, with water
flowing through inside it,
and stand offs to float it. Then use an external HE- radiator, high flow
rate, and a huge reservoir
in series with the flow lines...and loads of air on the HE. The .5 -2 gallon
reservoir acts like a giant capacitor.
Cooled water from the HE goes to the reservoir.... then to pump...then to the
heatsink.
From heatsink back to the input of the air cooled HE. An even better
medium would be to use FREON.
Big diam myriad of a labyrinth of holes in the copper heat sink... then the
in-out freon lines are reduced to
a small diam back to the compressor + external HE.....just like a freezer.
freon is liquid when inside a
small diam tubing. where it morphs into a large diam tubing, it turns to
gas.... and gets really cold.
Seems to me that water boils at 167 deg F at the top of mt everest..making
for lousy coffee-tea.
that’s due to low pressure. Dunno if vapour phase cooling would work at 167
degF in a partial
vac environment or not.
Another scheme would be multi-phase cooling..like used in some eimac tubes.
goes in as water,
morphs into steam.... then back into water..all inside the same tube. The
water goes in at high pressure
the steam formed does not get the surface bubbles. Well it does, but the
velocity is so high, it strips the
bubbles off as fast as they form. it’s a slick cooling system. You get the
best of both water and vapour
phase cooling.
Another method would be to just use water cooling..but use a massive reservoir
as the heatsink..like a
10-55 gallon drum just outside the home. Then its just a big loop..and no
water wasted.
Plan B would be to just use cold tap water like used for 50 ohm dummy loads.
Attach the garden hose,
and turn it on... then dump the warm water onto the lawn some where.
those bird and cd water
cooled dummy loads use a garden hose fitting. they will dissipate one helluva
lot of CCS heat..and fast.
For a 1.5 kw SSB-CW or even RTTY , SS amp, you would not need any where
near as much flow rate.
once cool, like for extended RX, flow rate is zero.
Ok roger... pick on and build it for us.
later.... Jim VE7RF
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|