[Boatanchors] suppressor grid modulaton

[Jim Haynes]

My first experience with suppressor grid modulation came when I first
went to college.  The electronics laboratory was also home to the
university ham club, and was occupied by a BC-325 transmitter.

The BC-325 was the conceptual ancestor of the military system that
had a BC-610 in a vehicle.  This one had come out of a military truck
that had a hole in the floor for belts to drive a generator from
the truck engine, whereas the later system used a generator in a
trailer.  I believe only a few of these were built and tested before
the BC-610 design was found to be more suitable and rushed into
production.  The BC-325 was about five feet tall, had knobs and meters
all over it, and had two 803s in parallel in the final.  It operated
CW or AM with suppressor grid modulation.  Although the case was made
of aluminum it still weighed a ton - makes you wonder if they left out
a plate modulator to save weight.  One feature was a little one-inch
oscilloscope that could display trapezoidal or wave-envelope of the
signal as a way to check on the modulation.


jhhaynes at earthlink dot net