Thanks for the info. Paul, very interesting.
The supply voltage drops from 40odd to 30odd volts with power
reduction so I'm guessing the current drops 20% or so, with
dissipation roughly halving.
Steve
Steve,
I did an unscientific check with my SPE 1K. Ripple on the RF
envelope at the 1KW level is no worse than with my Alpha 77Dx
and 87A at 1500W. It's just noticeable on the scope at the
maximum power level. Yes, total drain current is about 40-42
amps.
If the QST Product Review is any indication of the amp's IMD
performance, 3rd-order 2-tone is about -40 dBc. Not sure how
well that figure holds up across a sample of units. The IMD
spectra of the 2K model appears very close. Apart from fault
detection and T/R, I've not spent much time with the rest of
the schematic so it would be interesting to see how they
achieve reasonably good IMD at full power that's competitive
with many VT amps.
These are not "brick-on-the-key" amps. In the case of the 1K,
the software automatically cuts back power to 50% after about
15 seconds. I don't run high duty-cycle modes like RTTY, but I
think it would be a painful experience in a contest between
automatic power reduction and fan noise. For me, it's a good
instant-on alternative for my operating modes, but it would not
be my only amp.
Paul, W9AC
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