Date: Mon, 6 Mar 2017 14:44:51 +0000 (UTC)
From: Catherine James <catherine.james@att.net>
To: <amps@contesting.com>, Manfred Mornhinweg <manfred@ludens.cl>
Subject: Re: [Amps] SS amps watercooling
I would say the consensus is that air cooling is much simpler than liquid
cooling, even if large, noisy fans are needed and the case has to be carefully
designed to force flow in the right places.
It's not a coincidence that air-cool ham amplifiers are common, while
liquid-cooled one are rare.
Long term, I hope we can follow Manfred's suggest to move toward Class E and
other amplifier designs that are much more efficient and need less cooling.
73,
Cathy
N5WVR
## In the UK book, Radio Transmitters , R.F. Power Amplification, written by
VO stokes... which I posted in 3 parts on the yahoo amp group under the files
section.... they cover
everything from 1kw to 500 kw. This is all tube stuff. Interesting to note
they advise against using water cooling, and to avoid it like the plague.....
simply cuz of the
complexity, cost, maintenance, and the pita involved. They recommend Air
cooling, preferred, and simpler. For broadcast use, who really cares how loud
the centrifugal blowers are. A pair of CX-33 blowers
will easily cool a single 4CX-15000....and is a typ cooling setup for FM
broadcast. 3 x CX-33 blowers will cool a single 3CX-20,000A7. Those blowers
and similar from ebm papst
and also Kooltronics will run 24 7 365 for years on end. Just change out
the furnace style filter. The latest offerings from 3M for furnace filters
are superb. Acordian shaped, for max surface area.
They filter out dust, pollen, mites, and anything else you can think off. A
lot better made than the bottom line plane jane dust filters. They come in all
widths and lengths, typ 1 inch thick. Then you don’t
have to be cleaning the blowers, and tube fins, etc. Biggest air cooled
tetrode in the Eimac catalog is the 4CX-35,000.
## I dont see any class D, E, F, G amps that are linear....for HF ssb use..
like the 2-30 mhz variety. I keep looking, but dont see any....yet.
Manfred mentioned a while back about using a conventional Pi or PI-L on the
output of a SS amp. I drew this out on paper, and my conclusion is, you would
have to be damn careful tuning it up..and pulse tune it
with a low duty cycle. With your typ 50 % eff SS amp, mistune it, using a
cxr and... kablamo.
Jim VE7RF
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