[RTTY] Funny you should mention.....

[Kok Chen]

On Mar 30, 2012, at 7:56 AM, Hank Garretson wrote:

> Indeed. My first RTTY was in 1959 with a polar-relay keyed diode changing
> my Viking Ranger VFO frequency. It worked, but I had lots of problems. That
> was FSK in spades.

This reminds me of the time VY1JA was getting back on the air after an absence.  He had earlier sold his rig, so I sent J. my unused Omni V.  The V was one of my backup rigs to my Omni VI back then.

I think it bounced on a truck all the way to Whitehorse after clearing customs in Vancouver BC.  

Since an RTTY Roundup was coming up and there was no RTTY activity from the Yukons back then, I nudged J. to operate RTTY.  Heck, he created hugh CW piles even during Sweepstakes.  Yukon was kinda rare back then, period.  Not just on RTTY.

When I found his RTTY signal, it sounded constipated.  But decodable (I am sure it is not decodable under low SNR).

The Omni V and VI generate FSK by switching a trimmer in the tank circuit of a local oscillator.  The LO is subsequently mixed up to RF using crystal based oscillators and the VFO.

Well, when J. took the Omni apart to probe it, he found that the trim cap had drifted during the rough trip; from a 170 Hz shift to something like a 40 or 50 Hz shift!

Those were the days when you had to keep an eye on FSK transmitters, unlike the Keyed AFSK transceivers of the same generation, such as the FT-990 and FT-1000D, where there is nothing to adjust to maintain the correct shift.

Funny thing is that later in 2004, VY1JA was my first on-air RTTY contact after completing cocoaModem.

73
Chen, W7AY