>> Often, money spent on a better feedline or the replacement
>> of an old one
>> might yield better results than trying to squeeze 700w
>> (dirty) out a 600w
>> (clean) amp.
>
> That's true with tubes and many HV FET's, but with bipolar
> transistors the distortion starts to ramp up long before
> anything close to saturation occurs.
I'd like to build a solid state amp capable of running the legal limit plus
a wide safety margin with the HV (50 and 100) FETs available today, but the
price of mistakes is a bit steep<:-)) Then the control circuit for over
current, over voltage, SWR shut down, excessive drive shut down, and drive
on the wrong band gets a bit more complicated. OTOH with today's ICs the
shutdown can be done with little delay. Although it's been a while I think I
could handle the machine language programming. I'm just not so sure about
the measurements.
My Tokyo HK-1.5Kfx runs almost as much power out on HF as does my old Henry
2K4 without near the heat. OTOH my *old* Alpha 76A doesn't throw out near as
much heat as does that 2K4 either. Then again, I could purchase a lot of
electricity for difference between what I paid for the 1.5K and the 2K4
<:-)) Even in good shape and with a good pair of tubes the old Henry amps
are typically in the $700 range. Some go higher, but they need to be one of
the *BIG* ones to bring much more. I see quite a few with the initial bids
around $1200 that end with zero bids. They are big and they are heavy. Not
exactly table top.
73
Roger (K8RI)
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