<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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