[ARC5] Netting Switch

[Mike Morrow]

I wrote:

>> A simple netting switch can be added to an otherwise stock
>> command set system by installing a SPST switch that opens
>> the keying line from pin 5 of modulator connector J-52 to
>> the receiver rack.

Jack wrote:

> I did this on an SCR-274N set I built up. And it worked, sort
> of.  The problem was that even though the receive antenna line
> is grounded by the antenna relay, there was still enough
> signal picked up by the antenna wiring, to overload the
> receiver.

Yes, that's its biggest problem.

Still, I believe it would have been better than nothing in
actual service use.  It sets up the exact same situation for
the command set that is established for the SCR-287-A and
AN/ARC-8 liaison sets when their MONITOR-NORMAL switch is
in MONITOR.

What about the over-signal mess that happens with the ARB/ATB
when one tries netting those two?

> I now use a spotting oscillator, using the circuit from
> the TBX calibrator. But, it needs a crystal on the frequency
> of interest.

Ah...But that's not what the intended users did.  I understand
trying to operate this old gear only when it is operated
in precisely the original manner and configuration that its
design, good or bad, established.  I would not even implement
the command set netting switch I described, since the intended
users did not have that.  If I wanted to "improve" an old set's
performance with non-military customizations, I might just as
well go full Japanese solid state and get orders of magnitude
better performance on both transmit and receive! :-)

The approach that is closest to original would be to use a
SCR-211-* or LM-* as the command set cal signal source.  I doubt
that the O-4/ARC-5 ever found any use in that role, since most
AN/ARC-5 communication receivers were fixed lock-tuned prior
to flight.

Mike / KK5F