[Amps] How light can you make a 500W amplifier?

[yo9fzs]

The E class 7MHz CW only amplifier article was
published in the May 1997 QST.
Two versions were described in the first part,
a 300W (IRFP440) and 500W out (IRFP450).
The second part described a linear keyed PS.
Later, in the jan/feb 2001 QEX a keyed
switching PS was presented.

I found long time ago these articles as pdf files on the www.
Also found other files for a 400W 13.56MHz E class ( IRFP450),
a 200W 10MHz E class (IRFP440) and 7MHz 1 kW E/F2 class
(two STW20NB50) amplifier designs, all from the same author.
I can send these files to anyone interested.
Of course, all these are not linear amplifiers.


73's,
Traian




"George K. Watson" wrote:

> >> Is this daffy????
> >> 73
> >> Bill wa4lav
>
> No, and efficiency and weight can be helped further by running at higher DC
> voltages using off-line buck style converters.
> I have run class E cw at 46Mhz using 100V off of a buck converter for 300W
> continuous in an industrial application. There are isolation issues in off
> line operation and the tuning components for class-E can be a weight factor
> at lower frequencies, but the sweeping statement below has some traction. Of
> course, the devil is in the details. Eliminate the SSB/AM requirement and
> you can get rid of quite a bit of weight. An example is found in a QST
> article from a few years back by Dr. David Rutledge at CalTech. His 700W CW
> 7mHz class E amp used a $5.00 part, ran at up to 140VDC and weighed about
> .5Kg, not including a power supply. The power supply was heavy, but this
> could be alleviated with a switchmode supply.
>
> George K. Watson
> K0IW
>
> At 02:43 PM 10/15/02 -0400, ToddRoberts2001@aol.com wrote:
> ><PRE>In my opinion the future for lightweight SSB amplifiers would be a
> >solid-state amplifier based on EER ( Envelope Elimination and Recovery)
> with
> >a Switching Power Supply. An EER amplifier can use a Class-E Power amp with
> a
> >typical power efficiency of 90% and a Class-S switching audio amp with
> >typical power efficiency of over 90%. Such high power efficiency allows use
> >of a much smaller heatsink and cooler and more reliable operation of the
> >final transistors. A 500 watt output amplifier @ 90% efficiency would
> operate
> >nicely from a power supply of about 50VDC @ 11 amps. SMPS are available
> with
> >power factor correction of 99% and overall efficiency of 85-90% and they
> will
> >operate over input voltage range from 100-240 VAC / 47-63Hz  auto-detect. A
> >50VDC@11Amps SMPS would weigh about 5-6 lbs or less than 3Kg. The Class-E
> >power amp and Class-S modulator could be built with a weight of about 5-6
> lbs
> >also, for a total weight of 6Kg for the power supply and 500 watt output
> EER
> >amplifier. The whole thing could be put into a table-top cabinet about the
> >size of a Collins 30L-1 without much trouble and probably not weigh more
> than
> >7-8 Kg.  73 Todd Roberts WD4NGG .
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