Hi Larry,
All of the links and data agree with what I found here in my measurements. I
think the real issue is some very creative marketing is being done, and the
factory data sheets can be a bit confusing. They certainly do not contain
linear data.
Here are the main points:
1.) The "1250 watt device" is actually about a 800 watt PEP maximum device
in linear service. At 800 watts, it is right on the edge of what we are
accustomed to for Ham product IMD.
2.) A major problem is heat. Because all heat is in one small footprint, it
needs a very thick machined copper spreader or liquid cooling, even at just
800 watts PEP.
3.) Like any other device, they will fail with mismatch at high power. They
absolutely will require SWR shutdown and temperature monitoring.
If we read all of the links carefully enough to cut through the marketing
fluff, we will see every reference link listed (where they have actually
tested) agrees with all of this.
I think what has really happened, is many home or first-time builders have
taken the data sheet at face value. They have convinced themselves this is a
1250 watt output device that can be run right into almost any load without
worry. Of course, neither of those things are remotely true.
I understand it is tough to let go of the magic of a single 1250-watt device
that slapped on a heatsink without protection, and can be run into a 65:1
SWR without failing. But this is really a 800 watt PEP linear device that
comes with all the long term baggage of any other similar device, as ALL of
those links also seem to agree with.
At 600 watts it will be pretty clean. At 800 watts about at the lower limit
of what cheap tube amps can do. All of this requiring getting the heat out,
and shutting it off if SWR goes high.
73 Tom
<<<<<Like Tom, I am convinced that it is not possible to run that part at
full power in normal amateur service due to the heat issues. Maybe some
energetic person will build one up for 1.8 MHz using cryogenic cooling and
let us know how that works out...
73,
Larry - W7IUV>>>>
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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