[ARC5] Netting Switch

[Kenneth G. Gordon]

On 27 May 2013 at 9:12, Robert  Eleazer wrote:

> It sounds like the best thing that could have been done with the WWII
> Command Sets would have been to have a switching system where receiver
> B+ was applied to the transmitter oscillators when they were not
> transmitting, enabling them to run all the time and provide a weak but
> readable signal so to allow zero beating the receivers with the
> transmitters.

Well, as a CW operator, I would have found that method to be very, very 
annoying. Leaving the transmitter oscillator running constantly makes 
effective communications on CW very difficult.

Even at the weakest it possibly could be set, it would still mask weak signals.

On AM, it would still be bothersome, although of course, not as badly. One 
would only hear the "weak" carrier when another station was "in there". 
However, it would still mask weak AM signals too.

No thanks.

That is not a good method for netting.

Effective netting requires the transmitter oscillator to be able to be turned on 
and off for netting, AND to be stable enough to not be off that frequency 
when controlling the transmitter.

Or one could use an FSK method to move it so far off frequency at key up 
that it couldn't be heard. But then for netting, one would have to arrange the 
circuit to shift the oscillator to the transmit frequency during netting.

I am quite surprised that Dennis' T-22 pulls 2.7 KHz off frequency when 
driving the final amp. That would not be acceptable to me, although he is 
essentially using the FSK method mentioned above, so it works for him.

One method to deal with this sort of thing "back in the day" was to switch a 
load onto the oscillator when it was keyed alone that would exactly mimic the 
load that the transmitter provided when driven by the oscillator. 

In fact, when power supplies had very poor dynamic regulation which caused 
frequency shift when keying the rig, some operators would use a double-pole 
relay to connect a load to the power supply at key up that drew the same 
current as the transmitter did at key down. This also minimized chirp caused 
by that poor dynamic regulation. Keying speeds were usually pretty slow, 
though.

Ken W7EKB