[Amps] Expert 1k amp

[Steve Thompson]

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
> 
>