Bought a Hallicrafters S-77A All-Band Communications Receiver

After years of using the old Viking tabletop radio to listen to my beloved shortwave bands, I saw an advertisement in the classified section of the Winnipeg Free Press, for shortwave radios.  A fellow named Mr. Hall, who lived down on Landsdowne Ave (a rough part of town now, but not bad then), had some radios for sale.  I had a bit of money saved from my paper route, and convinced my dad to take me to see them.

I paid $20 for a Hallicrafters S-77A communications receiver.  Wow, what a difference!  I used that radio for many years, and when I got something better (a Yaesu FRG-7), I took it out to the family cabin, where I used to listen to shortwave on lazy summer nights…

Hallicrafters S-77A

While at Mr. Hall’s place, I was bedazzled by the vision of an amazing, complex, wonderful radio – a full carrier-mounted Marconi No. 19 Set Mk. III!  I asked how much it was… and decided that I had to have it, too.

Toying with Television

I had very little money, but I did want to toy with television technology.  My oscilloscope was a DeVry Technical Institute tube type, with recurrent sweep (as opposed to triggered sweep), which made it difficult to capture signals.  I was given an old TV with no picture… so I pulled the horizontal & vertical signals from the circuitry, sync’d the ‘scope’s horizontal to the horizontal retrace pulse, drove the vertical with a pulse borrowed from the vertical drive (which was a challenge, because most places in the circuit, it was highly nonlinear, but I found one where it was reasonably linear), and fed the raw video signal to the intensity modulation input on the rear… and recreated, for a brief moment, a full image on the ‘scope!  Then I slipped with my probe, popped a high voltage capacitor, and lost the signal.  For years, I sought a replacement capacitor, until such time when I could find one, I realized that I hadn’t documented which capacitor had failed, or what its value was.  Sigh.  Oh well, it served its purpose.

Devry Technical Institute oscilloscope similar to mine


Experimentation with TTL and Making a Television Transmitter

I built 8 digit frequency counter using Vector wire-wrap technology, but my front end design had poor sensitivity.

Then, for the science fair, I designed & built a simple TV transmitter, with horizontal & vertical retrace counters and end-of-frame equalization generator.   I obtained a still-functioning Plumbicon camera tube from a local TV station, and proceeded to build a camera frame around it, using deflection coils from an old television set, and a home-brew high voltage power supply using a tube-type TV’s power transformer.  I was unable to get the camera to function, but I was able to generate a raster that I could sync a black-and-white television to!

Later, I developed “TV typewriter” using TTL logic, hand-drew schematic on large sheets of paper, but once I was introduced to the PC, that fell by the wayside.

Hacking the No. 19 Set

After buying the Hallicrafters S-77A, I was enthralled with the other radio that Mr. Hall had.  He wanted 75 for it.  I counted my pennies, scraped and scrounged, and a couple of weeks later, my dad took me back to get it.  I thrust73 into Mr. Hall’s hand and said, “this should do it, can I take it now?”

We hauled it home.  Then hauled in a car battery to run it.  It was a shortwave AM/CW transceiver, nominally 25W final output (although who knows with the bad matching finals), and a VHF AM transceiver – but the VHF was rather useless, honestly.

No. 19 Set Mk III

I spent many a night playing with that set, repairing and modifying its circuitry, sending covert music transmissions which I’m sure nobody but the neighbours heard, and just generally learning about radio and high voltage.  Oh, did I mention that it had a motor-generator set that pushed the 12V battery signal to about 520Vdc (well nominally, with a very high pitched MG set whine), for the HF RF final amplifier?  Yeah, I got a few pokes off of that one.  That hurt a lot more than the 260Vdc vibrator-driven B+ for the receiver!  Heh heh.  But I survived… and gained a grudging respect for high voltage DC.