Originally Posted by dxhound
Hence the SOME part, I would never try anything on my own amp like this, but since he gets to play a little bit, we might as well have some fun.
And if each transistor produces 150watts Po and the amplifier is 60% efficient, with a dis. rating of 300 there is some wiggle room. and thats taking into account loss in the output combiners and filters.
The voltage adjustment I was asking about isnt to VOLT the amplifier per say. But instead have the amplifier stay closer to its rated voltage under load instead of sagging so much.
The increase in IMD will completely offset any increase in Pout you would see.
I mean, let's blow up a thousand dollar amplifier to get another 100 watts on the meter?
You want the amp to not sag, build a better power supply, DON'T increase the dissipation the transistors are having to deal with. Remote monitor the voltage on the collectors and then feed that back to the regulator, as linear supplies do....... THEN, you don't have the 'fluctuating voltage' issue... Otherwise, ANY voltage fluctuation causes IMD and can cause other issues as well.
I'm failing to follow your math, anyway. If each transistor is capable of 300 watts of diss., then that equates to 180 watts output at 60 percent eff. THEN, take 10 percent off for the xformers, oh wait, another 10 percent off for the COMBINER, and you're right back at.... Oh hell, 180 * .8 = 144 watts OUTPUT for each transistor, TOTAL OUTPUT for the stage.......
Whoops. It's that physics that f*cks CBers up every time
Also, on a FET, voltage plays a HUGE issue. To have 50 volts on a FET, in amateur service (where 1:1 VSWR is NOT always the norm), you better have devices capable of 200 volts, MINIMUM.... I'd go 250 or better.. There MIGHT be a reason Ameritron isn't running their amplifiers balls to the wall... Or Alpha... Or THP, or any other manufacturer besides CB
junk. BUT, back to the original meaning, if you increase that voltage so the FET sees 50 volts across it, and have any VSWR, it could mean bye bye fets.
I KNOW Yeasu had issues with this exact thing in the radio I own.....