RTTY Recollections
I arrived at Queen's University (Kingston, ON) in the late summer of 1982, a bit apprehensive about the journey ahead. To help ease the transition, I spent that first year in the men-only (at that time) McNeill House residence. Since I shared this room with another first-year Engineering student, I set up my Heathkit HW-100 underneath my bed, to least intrude on our modest space. My clandestine antenna was formed from TV yoke-wire and dental-floss - it's fragility combined with the awkwardness of operating from beneath a bed quickly led me to look around Campus... where I discovered the Queen's University Amateur Radio and Electronics Club (QUAREC).
The club had a few remaining members, but was without a "home", nor antenna. When I expressed interest, these remaining members were sparked to action, and we erected a tower (Delhi Golden Nugget?) and Mosley TA-33Jr antenna on the top of Goodwin Hall. The Co-Ax and rotor-cables were simply dangled down the exterior of the building, through the slightly-open window, and into our new radio room. And it is here that I first encountered RTTY (Radio Teletype).
The QUAREC station consisted of a Yaesu transceiver (FTdx-400?), TV rotator, and a Model 19 Teletype Set: Model 15 Page Printer and tape-perforator, and also the Model 14 Transmitter-Distributor (TD) tape-reader. At first, I operated CW and SSB, but my fascination with the unknown RTTY mode grew... None of the current QUAREC members knew anything about RTTY, and really only had modest interest in operating the newly-revivified station on SSB.
I grabbed an ARRL Handbook, plus found some other material, and learned RTTY basics. With some cleaning and generous amounts of 3-in-1 oil, the Model 19 Set began to work! I was hooked... hooked on the sensual smells, sounds, and feel of classic RTTY and a tube-type Terminal Unit (TU).
A couple of years later, as I prepared to enter my final year at Queen's, we had to re-locate the station to the Old Medical Building. By this time, club membership had dwindled to maybe only me, and the Faculty Sponsor (Dr. Jim Mason). But with a few years' RTTY operation now under my belt, and having read more-widely, I decided it was time to rebuild the terminal unit to the famous Chemical City Terminal Unit design. The chassis was stripped, modestly re-configured, and re-wired and improved ("improved" = more 88mH inductors for better filters, and the use of both mark and space detection for greater accuracy) . Although our antenna system was nothing like we had atop Goodwin Hall, the complete rebuild of the TU improved this part of the equation, and casual RTTY operation continued in 1985. Along they way, I had acquired official Teletype Corporation manuals for service and adjustment of the various Teletype machines, and tools for this work also.
By 1985, technology was moving forward and beginning to pick up speed. I read some articles, and fused together my experience in rebuilding the old tube-type TU with newer solid-state and op-amp technology. The result proved very compact, and worked very well when combined with the Model 15 Page Printer. Active filtering of Mark and Space tones, followed by low-pass filtering and slicing formed the classic receiver processing. For the transmit side, I used the super-duper-fancy Signetics phase-continuous FSK chip. We were about the enter the realm of AFSK in a technically "clean" manner... Once the bugs were worked out and this solid-state TU was working great, I wrote a paper detailing it's design and operation, which I entered into the local IEEE Student Papers Competition. And, I won at his local level. I didn't do so well at the regional level, though, where the competition was very professional and of a very high calibre (with corporate support even, which makes hobbyist-level presentations challenging).
Following University, I moved to the West Coast in the Spring of 1986, where I began a career, got married and built a home... I also had only SSB/CW capabilities, so RTTY was put "on-hold" for a few years.
After this pause, though, things got really interesting, really fast!
First - a friend gave me a Model 15 (standalone) Page Printer. I managed to acquire a couple of standalone Model 14 TD's, and blew the cobwebs off my solid-state Terminal Unit. I modified my own HW-100 with a diode and capacitor, to permit true FSK (by shifting the VFO), but I quickly returned to AFSK operation...
Second - I had a job, new home, wife, and no kids in 1992. So, I bought a higher-end radio: a Kenwood TS-850S/AT! Wow! With this, I had a dedicated FSK port on the back of the radio, but I also had great frequency-stability and accuracy. My old TTY gear worked nicely with this shiny, new '850, and I used that for a few years. I never really used the FSK capability, instead choosing (and staying with) AFSK. With the '850 I could select my narrow CW filters even in SSB mode for AFSK RTTY! This was (is!) an awesome capability.
Third - home-computers had been around for a decade by the 'mid-90's, but they were kind of specialized and occupied places like dens, offices, or studies in the home. You really only needed one of them, right? WRONG - by running a modest PC with Microsoft's Disk Operating System (DOS), I made the leap from the sensual "Green Keys" to the world of the "Glass TTY". On the PC, the application I used at the time was HamComm - this required a simple op-amp interface, which sliced the analog audio from my radio, and produced squared pulses with clean (and measurable) edges, sent to the serial-port. Transmission was performed by toggling a serial-port output and filtering it, then applying this signal to the mic-input for AFSK.
This was good for quite a few years, actually, and having a dedicated 8086 DOS computer for the ham-shack made it easy to casually squeeze in a bit of operating-time.
On a parallel, but as-yet-unrelated path, in the early 1990's I became interested in the GNU/Linux operating system, and began exploring and working with this. Eventually a Linux computer migrated into the ham-shack, but was used for non-ham-related things like email, and web-surfing.
In the early-00's, an exciting development appeared - the use of your computer-sound-card as the interface between radio and computer! The sound-card could perform Digital Signal Processing (DSP) to isolate and determine the tones, then application-software could decode and display the RTTY text. For transmitting, the application software commanded the sound-card to produce AFSK tones, and also toggled my '850 into transmit. But perhaps the coolest part was the ability to see your whole receive-spectrum, and work a station on any frequency in your audio spectrum! We weren't stuck with 2125/2295 tones any longer, and I could now use my '850's ability to select narrow CW filters even in SSB modes!! What's more - the transmitted tones were set to exactly match the incoming selection, so I was always on-frequency/zero-beat with the other station.
In this early-00's phase, the simplest interface from radio to computer was just an audio-cable... this worked, but often suffered from hum. After testing just a straight cable, I made a small home-brew transformer-isolated unit, but eventually migrated to a West Mountain RigBlaster Pro - transformers and optocouplers kept ground-loops and hum away. In a similar vein, my Linux RTTY software progressed from twpsk, to gmfsk, to fldigi.
With the use of sound-cards, in the late-00's, an explosion of new modulation schemes appeared. Now that the radios were stable and accurate, and the interconnection from radio to computer was clean, simple and reliable, it all came down to the software on your computer. Although I still pursue RTTY contacts, I have expanded into PSK-31 and dabbled in other modes too.
In early 2011, ~30 years after making my acquaintance with RTTY, I entered my first contest: ARRL RTTY Roundup. At this point I was still using my venerable TS-850S/AT, Rigblaster Pro, 134ft off-center-fed (OCF) dipole, and quad-core Linux computer. With the AGC'd-audio-output from the rear of the '850, it is possible to operate RTTY in total silence, but I need the reassuring "deedle-deedle-deedle" sounds. The use of macros sure beats feeding perforated-tape, and automated logging sure was nice. My contest effort was modest and casual, balanced against the attention given to wife, sons and family.