[GreenKeys] Autostart freq for 170 shift RTTY

[w9ddd at tapr.org]

Hi all,

I'll make some comments that aren't necessarily facts, bit tidbits that may help trigger some one else's memory.
First amateur RTTY was only allowed on VHF and higher frequencies. Why 2125 and 2975.  The 850 shift was in use on commercial circuits. Some commercial used 425 shift. 2125 is fifth harmonic of 425. 2975 is seventh harmonic of 425.  You can crate a frequency standard with a tuning fork (I made one).  Mark was probably low because a closed keyboard contact switches in more capacitance, therefore lower frequency.  Not sure why space is low on HF.  Also inherited from commercial use?  Not much SSB in use at the time hams were granted HF RTTY! Even less folks would have thought of using the SSB mode of a transmitter to do RTTY in that era.

I'm still trying to remember how I did 14,070 auto start with a KWM-1 around '71.  I remember I was shifting the PTO by making an adapter that plugged the PTO tube socket, running in CW mode and dropping the drive level to keep from overheating the finals.

John, W9DDD


> On Dec 30, 2020, at 3:57 PM, Harold Hallikainen <harold at w6iwi.org> wrote:
> 
> OK, I did not even think of specifying center frequency! One more thing to
> add to the list. If you are within 10 Hz with the LSB carrier on an even
> kHz (like we are now with 086), I think that should be good. I will add
> center frequency to my list.
> 
> I always remember LSMFT (low space makes fine teletype). It's interesting
> that with AFSK it is reversed, and seems to always have been the case. I
> guess they assumed we were using LSB receivers (which is generally the
> case below 10 MHz).
> 
> I will continue to be on autostart 7.086 MHz LSB and 14.086 MHz LSB. If my
> receiver unsquelches with a signal up a kHz or so, I'll tune up there.
> 
> 
> THANKS!
> 
> Harold
> https://w6iwi.org
> 
> 
> 
> -- 
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