[GreenKeys] Are there any telephone switchers in the group?

[Harold Hallikainen]

A little more on this.

When in junior high, a friend found a busted up pinball machine at the
Berkeley CA dump. He brought home the pieces and we made a common talk
selective ring telephone system (like the intercom in 1A2 systems) using
one of the stepper relays.

As mentioned before, when in high school, I built a small 2 digit step
system using equipment discarded by Pacific Telephone. Also while in high
school, we knocked on the door of the local CO and got a tour of the step
office!

In college, a friend worked for Western Electric, installing and
maintaining equipment at the ATT cable landing station in San Luis Obispo
CA. This was an underground building (I think it was 3 stories) mounted on
springs. It was the termination of a coaxial cable that went to Hawaii.
The repeaters along the cable were all vacuum tube. They were powered by
-3kV applied at one end of the cable and +3kV at the other end. The voice
circuits were all SSB frequency division multiplex. I remember as a kid
hearing "monkey chatter" in the background on long distance calls. They
also had TASI which would switch portions of conversations amongst the
different voice circuits available to fill the gaps in the conversations.
This is a sort of analog packet switching but used a separate circuit for
addressing instead of including the addressing information in a digital
header like we do now. I understand that later they replaced all the FDM
equipment with a high speed modem at each end of the cable so they could
pass digital voice or digital whatever. Finally, I think the cable was
donated to the University of Hawaii. Now the San Luis Obispo area has a
lot of fiber optic cable landings.

When I met my wife, she worked in engineering for General Telephone in
Santa Barbara CA. She assigned cable pairs and programmed the switch to
customer requirements.

When we lived near Denver, I volunteered for the Telecom History Group (
https://www.telcomhistory.org/ ) there. I learned about it from a local
newspaper article about the machines that would tell you the time when you
dialed POPCORN. I scanned a bunch of the Mountain States Telephone and
Telegraph Company newsletters (the Monitor at
https://bh.hallikainen.org/thg/monitor/ .).

This old technology is fascinating. It is amazing what they did
mechanically or electromechanically (with relays). Now the complexity is
moved to semiconductors and software while the mechanics is kept simple.
Compare the mechanics of a Teletype model 15 or 28 to that of a 43 where
it's just paper movement, print head movement, and print hammers. Then
move to something like an HP inkjet where the mechanics is just paper
moving and print head moving. The actual printing is done with little
heaters boiling the ink to blow a droplette of ink out a nozzle towards
the paper. There IS considerable complexity in the paper handling to get
it to print on both sides of a sheet.

Another area of improved simplicity is digital displays. For years, we had
complicated displays like Nixies, columns of incandescent lamps,
incandescent lamps projecting through filters onto a frosted glass screen
for each digit, and who knows what else. Compare that to the 7 segment
display! And we did not need LEDs or LCDs to do 7 segment, since there was
the RCA Numitron incandescent 7 segment display.

So... the development of technology is interesting! It takes time for
stuff to be figured out and then be improved upon. I like the quote "Time
is what keeps everything from happening at once." (
https://quoteinvestigator.com/2019/07/06/time/ ).

More than you ever wanted to know!

Harold
https://w6iwi.org

-- 
Not sent from an iPhone.