I know water-cooling has been discussed here before, but I agree that a
well designed water-cooled SSPA has the potential to gain some traction in
the amateur market if the $ make sense. That said, I think it is
unrealistic to expect one of our ham radio manufacturers to offer an
"inexpensive" water-cooled SSPA for amateur use. The added complexity and
potential maintenance might be enough to put the water-cooling concept on
"ice" from a ham radio manufacturing point of view.
Having built a W6PQL 2 deck SSPA, the (3) 80mm fans do roar which doesn't
bother me terribly as I always wear headphones. I understand the SPE amps
get loud and the PowerGenius was not quiet in the video. Even with the fans
in my amp at full tilt, there is excess heat to dissipate especially when
operating a high duty cycle mode. This weekend, during WPX RTTY for
example, I have hesitated to run the amp at full power because of heat
issues. The amp does have temperature protection, but I would prefer not to
hit the thermal ceiling. I did modify the amp so I can keep the fans
running full-time while contesting which provides some benefit. If I am not
mistaken, Alpha recommend(ed) a secondary fan on the 8410 for RTTY as does
ACOM for the 2000A, so some of the popular tube amps are not immune to heat
issues either.
So far, this is about the closest I have seen to getting to where the
water-cooling needs to go (at least from another ham). I suspect in the
ISM/radar/broadcast world, water-cooling SSPA's is fairly straightforward.
http://www.pe1rki.com/MRFE6VP61K25HR5.html
I didn't see details on the eb104 site about the water-cooled copper
spreader. I would seriously consider paying a premium to know that there
would be a minimal chance of a coolant leak. I have built several computers
over the past few years. Due to fear of a coolant leak and since I do not
overclock my CPU's, I have never sprung for a water-cooler in any of my PC
builds. It does appear as though one could cobble together an external
reservoir/pump/fan/radiator system from the PC world to do the job as eb104
demonstrates. I have no experience in the thermodynamic calculations
required to insure adequate cooling, and I am a little suspect in the eb104
videos as his infrared probe gives inconsistent readings at times which
leads him to do the "Touch Test--->Is it hot?"
I have no air conditioning at my QTH which has led me to explore
thermoelectric cooling of the heat sink and/or building a mini air
conditioner (chiller) to cool the air at the intake to my amp. I have no
doubt, direct water cooling of the copper spreader is way more efficient
than any of the ideas I have cooked up.
Hopefully, other hams around the world will continue to work on improved
cooling and IMD solutions for SSPA's as the LDMOS technology seems to have
arrived. There are just a few more bumps in the road that if smoothed
likely will allow hams to "roll your own" water cooled SSPA at a reasonable
price with a high degree of success.
Changing the subject just a little, I knew Alpha had the PA-70V vapor
cooled amp with a 3VC1500A7. A little further search leads me to believe
that ~150 amps were built. I also saw Paul, W9AC had a PA-70V years ago. I
would be curious to read comments about that amp and how well did Alpha do
with engineering the plumbing. I suspect it was a beast.
73
Mark WH7W
-----Original Message-----
Here's a link to eb104's 2KW page:
https://tinyurl.com/zf8mgdr
Link to the video showing the combined PA on one module:
https://www.youtube.com/watch?v=gLCuWs5SdBI
Paul, W9AC
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Paul
Christensen
Sent: Saturday, February 11, 2017 8:53 AM
To: 'Amps Amps' <amps@contesting.com>
Subject: Re: [Amps] PowerGenius XL - Others
## Eventually somebody will come out with a water cooled LDMOS amp, with a
diplexer, low imd, and a switching supply to handle it all. IE: 1.5 kw CCS
rtty amp. Ok, at that point, you now have the real deal. If priced right,
tubes are history.
Jim,
It won't be long before someone offers a complete product, Presently,
eb104.ru supplies all the components to build a 2KW, water-cooled LDMOS amp.
Blocks include PA, combiner, LPF, directional coupler, and control.
However, you'll need to supply a 100-amp+ power supply. Several folks are
using parallel 70A switching supplies. Their website shows eBay links to
purchase water pumps, condenser and fans.
https://tinyurl.com/zvgfze7
Paul, W9AC
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