k5nwa wrote: >At 07:30 PM 7/11/2008, you wrote: > > >>If your going to run those tests how about biasing to class A and >>measure What the heck you might as well blow the competition >>completely out of the water while your at it. >> >>73 W9OY >> >> >> > >Curious, was the amplifier designed so it could handle Class A >operations? That is a lot of steady heat compared to AB class. > > > >Cecil >K5NWA >www.softrockradio.org www.qrpradio.com > >"Blessed are the cracked, for they shall let in the light." > > >_______________________________________________ >FlexRadio Systems Mailing List >FlexRadio@flex-radio.biz >http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz >Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ >Knowledge Base: http://kb.flex-radio.com/ Homepage: http://www.flex-radio.com/ > > > > > > Cecil,
If the transistors are biased according to their data sheet, they should have a quiescent current of one ampere per transistor. If Vcc is 13.8 volts then that is 27.6 Watts of idle current when the microphone is keyed in the SSB mode without any modulation. The drain efficiency is typically 60% which means that for 100 Watts output 166 Watts is dissipated in heat in the PA for a steady carrier. SSB usually runs about 30% duty cycle so the heat dissipated would be about 50 Watts. The efficiency of class A is typically 30% so the bottom line is that class A would require the cooling system to dissipate 100 Watts during typical SSB operation. 73, Tom W0IVJ _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kb.flex-radio.com/ Homepage: http://www.flex-radio.com/
