[R-390] Collins R 389 PTO Clone

[Bill Hawkins]

Group,

The R-389 is a mechanical marvel as well as electrical. The first
approach should not be to go digital just because that's what most
design tools do these days. Collins made many different PTOs.

The R-389 PTO spans 470 to 977.5 KC to cover 15 to 500 KC on the
low band. The 500 to 1500 KC band is covered by doubling the PTO
output frequency. The set has tuned circuits for the doubler.

The 70E11 PTO covers 2.5 to 3.0 KC (it may be solid state, Google
can't find a description). Mix it with 2.030 KC and you get pretty
close, with a 1.2 KC low pass filter.

The R-389 PTO (70H something) is large because of the low frequency.
Newer ones are smaller, but just as linear. That should leave room
for the mixer and low pass filter, and whatever gear reduction is
required to give it a 50 turn span.

Now we're down a bit from that $25K startup cost, no?

Bill Hawkins