Running low voltage bipolar transistors on a big antenna or
at high power is really not a good idea and the cure isn't
as simple as setting the zero signal idle current or adding
a harmonic filter. The last thing we need is stuff like that
on ham bands.
73 Tom
But that is exactly what you get with many of the name brand VHF bricks that
are sold as being suitable for SSB. The 12V bipolar devices are passive
biased and Ive measured one brand 180W brick reach zero bias at around 50W
output. It takes very little work to add an active bias regulator that now
allows acceptable IMD; published circuits have been in many of the better
known VHF and above yearly convention books. Many of those bricks are in
regular use driving big antennas at home and even big amps.
Many CB bricks can also give acceptable performance as long as the new owner
researches the device specs and makes changes accordingly.
Carl
KM1H
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