[GreenKeys] Continuing, nothing about Teletype art

Sat Sep 14 16:38:51 EDT 2019

All,

Please keep sharing these stories, even if unprovoked. I love reading them, and we need to preserve them in history.

People who are bored by them can simply skip to the next email.

-
Jordan Spencer Cunningham
teletype.net

On Fri, Sep 13, 2019, at 8:03 PM, Jim Haynes wrote:
> 
> During the college years I had frequent contacts with Bob Weitbrecht,
> W6NRM/W9TCJ who was then at Yerkes Observatory in Wisconsin. A good
> friend of his was a professor at Arkansas, "Charley" Fan, who had
> recently left Yerkes, so I got them together on RTTY several times.
> Bob was one of the great pioneers and promoters of RTTY, devising a
> lot of equipment and traveling great distances to help hams get
> started. There was one period when he and BeeP W0BP traveled together
> for a long distance, stopping to visit RTTY-ers all along the way from
> Minnesota to Texas and beyond. Bob was deaf, so ham radio was a great
> social outlet for him, and RTTY made his communication a lot faster
> than he could do with CW. He decided to leave Yerkes and came to visit
> us and the Fan family in Arkansas before returning to California and
> resuming use of his W6NRM call sign.
> 
> I enjoyed operating the RTTY contests in those early years. There were
> only two a year, and the number of RTTY operators was so small that many
> of us were acquainted with one another outside of the contest periods.
> Also W5YM was the only RTTY station in Arkansas, so everybody wanted to
> work us for the section multiplier.
> 
> When I told Merrill I had a summer job at Teletype he told me to look up
> Bob Reek there. He and Bob had been roommates at some summer short course
> on transistors put on by some university not long before. As it turned
> out Bob was my immediate supervisor both summers when I worked there.
> He is still living and we are still in touch.
> 
> Although Teletype Corp. was not in the radioteletype business we were
> working on time-division multiplex equipment for the Navy to use on RTTY.
> This was my first chance to work with transistors in large quantities.
> I didn't take to transistors very well in linear circuits since they were
> so hard to bias and stabilize. But we were using them as switches in
> digital circuits where they really excelled. At the time transistors
> were too slow to use in digital computers, so we were working with and
> manufacturing logic circuits ahead of the computer industry.
> 
> As to the original subject matter of this posting, RTTY art, I never
> paid much attention to it because on HF there are enough hits and dropouts
> to spoil just about any attempt to transmit pictures. Plus it takes up a
> lot of time that could be spent in conversation about RTTY. I guess
> RTTY art was more practical in areas where there were a lot of hams 
> operating VHF where copy was consistently good.
> 
> Back then in addition to amateur RTTY there was a lot of other stuff on
> the air we could copy. I remember when Sputnik went up we were very
> busy at W5YM copying all the press we could find and hanging it on the
> door outside the ham shack for the passers-by to read.
> 
> In the Air Force I had my own RTTY station, first in the garage of a 
> friend who was married and had a house on the base, and later in my room
> in the BOQ. I used the Model 15 I had put together from parts from W9GRW,
> and an old BC-375 transmitter modified to use a Heathkit VFO. Receiver
> was initially a BC-348 and later a Drake 2B. Later Bob W6NRM gave me
> a transmitter, Royal Canadian Air Force I think, that was less ponderous
> than the BC-375. It was intended for use with an external modulator
> for AM, so the transmitter alone was a fine CW and RTTY performer.
> 
> After the Air Force I went back to Teletype full time. I set up my RTTY
> station and had a lot of contacts with Irv Hoff who moved to California
> sometime in that period, and with Vic Poor at Frederick Electronics Corp.
> I didn't really contribute to the design of the ST-6 and the Frederick
> demodulators, but it was interesting to keep abreast of what those guys
> were doing. We had a ham club at Teletype, and I occasionally attended
> meetings, but for some reason I never got over to the building where the
> club station was located.
> 
> After 3 years at Teletype in Skokie I went with G.E. when they were in
> the computer business in Phoenix. I learned a lot about computers, but
> working for G.E. was a lot less fun than Teletype, at least for me.
> After two years of that I landed a non-academic engineering job with
> University of California, Santa Cruz and stayed there for 30 years.
> On the faculty were Harry Huskey, a computing pioneer who had worked on
> ENIAC, and David Huffman, famous for the Huffman codes and a lot of
> other important things. And continued RTTY in my spare time. I had a
> housemate WA6JYJ who was a friend of Bob Weitbrecht and whom the 
> university hired when he got out of the Army. Bob lived just about an
> hour away in Redwood City, so we got to visit each other often. By
> that time Bob was quite absorbed in the modem he had invented for use
> over phone lines by deaf people with TTY machines. But that's another
> story.
> 
> This was the period of time when integrated circuits became cheap, so
> we could develop a lot of stuff for RTTY quickly and easily. One thing
> I built was a speed converter so that a Model 28 running at 100 wpm
> could copy any of the standard speeds. Larry WA6JYJ also built one with
> a few changes from mine and wrote it up for Ham Radio magazine.
> 
> I was also interested in the possibility of improving RTTY reception
> by using a more advanced detector, one taking advantage of synchronism
> to know when the big boundaries were going to occur. The FCC rules for
> amateur RTTY had never permitted us to transmit anything other than
> 7.0-7.5 unit start-stop code. After a while I realized that I could
> transmit 7.0 unit code synchronously, putting in a fill character 
> whenever there was nothing available in time from the keyboard or tape
> reader. I built a circuit to do this and started using it on the air.
> I had a collaborator who was supposed to be working on a receiver for
> the signals, but I don't know if he ever got it working. In any event
> the guys who were experimenting with and using two-tone demodulation
> really liked it because it prevented the loss of space tone when a 
> keyboard user quit typing. I believe this is the origin of the "diddle"
> style of RTTY signaling that is almost universally used today.
> 
> I was really tickled many years later when I read of K6STI and his RITTY
> software that demodulated RTTY on a PC and that had what he called a
> "digital flywheel" that would synchronize to a repetitive FSK signal
> regardless of the length of the stop bit. This was what I had hoped
> to achieve with my diddler circuit and a purpose built hardware
> synchronous demodulator. Well RITTY was a very good demodulator, but
> the improvement we were hoping for did not materialize - the synchronous
> detection only helped a couple of dB of signal-to-noise ratio. I found
> an old government report where Stromberg-Carlson had developed a system
> for the Army that was pretty close to what I had in mind, back in 1958.
> The abstract to the paper reported a great improvement over standard
> FSK operaton. I was able to obtain a copy of this report - having to
> use a FOIA request to get it. It turned out that real synchronous
> detection didn't seem to help at all, because propagation through the
> ionosphere introduces so much variation in the arrival time of signals.
> 
> > I hope that my rambling is not boring to any or many. It is great to think
> > back to that time of my life and remember the 'good times'
> > along with the bad times. The nearly two years I spent on the USS Hancock
> > were most interesting and educational for me. 
> > 
> Not boring to me, and I hope my attachments are not boring to the group as
> well.
> 
> Jim W6JVE
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