[GreenKeys] CV-89

[Jim Haynes]

On Wed, 21 Oct 2015, Jim Sheldon wrote:
>  
> I did pick up an absolutely brand new HAL ST-8000A that was still in an
> unopened HAL shipping container and currently use it as my primary T/U with

One thing about the newer converters that the older ones lack is a 
built-in regenerative repeater.  If you drive a mechanical TTY with a 
CV-89 or ST-6 or whatever you get a lot of excess errors under poor 
receiving conditions.  If the STOP pulse is mutilated and the receiver
has a mechanical selector, the clutch fails to latch up and the machine
runs out of sync for several characters.  An electronic regenerator can
cope with this better since it can stop at any point.  Also you can get
false START pulses which an electronic receiver can sometimes handle.

Also if the transmitter is using diddle the receiver can in principle
synchronize to the received character stream, further protecting against
false START and STOP pulses.  I don't believe any currently-available
demodulator takes advantage of this; the K6STI RITTY software did.