[GreenKeys] Mod 28 Gearing

Steve Garrison steve.n4tty at gmail.com
Mon Aug 12 06:49:20 EDT 2019


I wouldn't use the words "which is better" but rather "which is more common."

The 60wpm, 7.42 unit code is more common.  That encompasses the start bit, the 5 data bits, and the stop bit that is 1.5 (really 1.42) times longer than the other 6 bits.  While there are machines out there running with the 7.00 unit code, there are more using the 7.42 unit code.

So I would go with the 161293 gear set.

Would I would like to see is the specifics of how/why the 7.00 unit code came along in the first place and how intermixing them in the same circuit effects difference in performance.  Anyone with a good explanation out there?

To my knowledge, which could be totally flawed, it was because of some of the crypto gear used in conjunction with TTY gear.

Steve G./N4TTY

-----Original Message-----
From: greenkeys-bounces at mailman.qth.net <greenkeys-bounces at mailman.qth.net> On Behalf Of John Lawson
Sent: Sunday, August 11, 2019 11:36 PM
To: greenkeys at mailman.qth.net
Subject: [GreenKeys] Mod 28 Gearing


Greetings Greenkeys!

I'm about to order a set of gears for the Tempest Mod 28, which I am told - (how to verify?) is a 75wpm machine. [hmmmm mebbe it ain't - best go check...]

Tom Tillson kindly sent a chart summarizing the gearsets for the 28s, KSR and ASR.

Of course my goal is to send and copy RTTY at 45 baud with this 28. It's a KSR so no re-perf or td.


So, from the chart, there is gearing for 65wpm - 390 opm, 45.5 baud, 
7.00 unit code. There is a motor pinion and the driven gear.

Keyboard (LAK)  gearset 173795   consisting of:

Gears:     173794 14 tooth

                  173793 100 tooth

Isolator   159287

Posts       161301  (need 2)


Gearing for 60wpm - 368 opm, 45.5 baud. 7.42 unit code

Keyboard (LAK) gearset 161293  consisting of:

Gears:     159278  14 tooth

                  159279  96 tooth

Isolator  159287 (same)

Posts      161301 (same)


Paul Cembura suggests  the 161293 / 45.5 / 7.42  set. I had originally 
asked him for the 173795 / 45.5 / 7.42 set.


I understand a bit of the relationships involved - but in practical 
terms - which is "better"??


Cheerz

John KB6SCO

Carson City NV


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