[GreenKeys] Gearset 28 conversion

[George Hutchison]

The early days of teletype saw power sources for teletype machines were often supplied by municipalities whose power was generated by small dams and plants running on frequencies from DC to 25, 50, 60 cycles and maybe a few more that could be all over the place when it came to frequencies.Ideally all of the machine selectors would start from zero and stop at exactly the ideal time to start another character.exactly 22 milliseconds after the last selector cycle ended. But, Podunk City Power, or Bob's Local Steam Plant, Aunt Minnie's Wonderful AC Bin and Pawn Shop, or Precision Pete's Mule Powered Hayburner and Threshing Machine Belt Driven Generating Plant were all running at different speeds, at which errors, garble, missed stop pulses, etc., caused editors to freak out and fire reporters, etc. The Genius Staff at the TELETYPE Machine Factory looked at the problem, and decided to allow a wee bit of additional time for all the machines to stop the selector cycle at a slightly longer time after the mark and space stream ended, and came to the conclusion that 9 more milliseconds to allow everything to be stopped before the next character started its journey to the world would help the situation out, thus the 31 millisecond stop pulse.When the National 60-cycle power distribution system became a reality, everyone could at last rest, allowing machines to be more reliably synchronized and far less garble was experienced. This made it possible to concentrate on more difficult problems such as selective fading between the mark and space frequencies of teletype signals emanating from radio transmitters running thousands of miles from their receivers. Decision threshold converters, running two transmitters  850 cycles away from each other, slideback detectors, and automatic threshold correction circuitry gave the engineers something new to play with.W7TTY

> 

> Wondering what percent of 28 stuff was other 7.42?

> 

Mainly Western Union, and machines W.U. supplied to the military.

I've posted an explanation of where 7.42 came from, but will refrain

from repeating unless someone asks for it.

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Message delivered to ad7i at ad7i.net
condition----- Original Message -----
From: ad7i <ad7i at ad7i.net>
To: Jim Haynes <jhhaynes at earthlink.net>
Cc: Greenkeys <greenkeys at mailman.qth.net>
Sent: Thu, 31 Dec 2020 23:09:57 -0500 (EST)
Subject: Re: [GreenKeys] Gearset 28 conversion
I'd be very interested in knowing the origin of 7.42.
Paul, ad7i

On Thu, Dec 31, 2020 at 8:48 PM Jim Haynes <jhhaynes at earthlink.net> wrote:On Thu, 31 Dec 2020, w9ddd at tapr.org wrote:

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