[NLRS] 432amp

[Dr. Gerald N. Johnson, electrical engineer]

As a rule of thumb, a solid state amplifier will not produce a greater
peak power on SSB than on FM or CW. Not even with a great deal of
distortion. The tube linear often did because of poor long term power
supply regulation that the short peaks of SSB could get out before the
power supply drooped and also because of the long thermal time constant
of the tube, especially sweep tubes with large peak plate current
capabilities allowed larger peaks than key down CW. And to run those
tubes at those conditions one didn't want to say "AHHHH" too long or the
glowing plate might melt the glass. That's not to say that the tube
driven that hard is still truly linear.

On the other hand a solid state amplifier is generally limited by a
regulated power supply and by peak collector current. Linearity as it
approaches saturation power (the FM rating) is often poor. We used to
get 3rd order intermod values in the -30 dB range, sometimes nearly -40
with 5th order generally 45 or 50 dB down. Now the latest super duper
rice boxes have 3rd order intermod only 25 dB down, with 5 th order only
35 dB down and higher order intermod showing well above the spectrum
analyzer threshold. This leads to polluted ham bands with splatter from
end to end and beyond.

UHF amplifiers are often more expensive than VHF amplifiers because they
need more stages to get the same power gain.

73, Jerry, K0CQ

-- 
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.