[TMC] VOX stability

[Sheldon Daitch]

Larry,

Many of the high end diversity receiving systems had AFC circuits.

Check out the CV-157 converter, for instance.

Also, the RCA SSB-3 Receiver system had an AFC circuit, and
I believe the Pioneer Diversity system also had an AFC circuit.

The transmitters for SSB/ISB and RTTY many times would have
a small amount of carrier (pilot carrier) injected into the transmitted 
signal and
the receivers had a sharp carrier filter and system designed specifically
to track this pilot carrier and keep the end to end system on
frequency. 

For instance, check out the second page of the MMX-2 sales
brouchure:

http://jptronics.org/radios/TMC/bulletins/TX/tmc.ssb_204-4115.pdf

Transmit characteristics, the level of carrier suppression is selectable,
specifically for that purpose.

These AVC circuits would keep the end-to-end frequency error under 1 Hz,
if working right.  It didn't mean the system was on the absolute correct
frequency, just the system was together.



73
Sheldon



TELEGRAPHER at att.net wrote:
> What would the requirements as far as stability of a transmitted signal have been back in the 60's?  Whether high seas, Navy, Attache, etc.  Now i am asking this concerning an AM signal.  This unit with drift of + or - 100 cycles could not have been useful in CW, SSB nor RTTy service.  Should an end user expect 20 cycle accuracy?
>
> larry
> W0OGH
>
> l
>