[GreenKeys] M15 with Polar Relay -- Configuration

Wed Jan 27 06:15:46 EST 2021

Sounds as though you think you must drive your machine with a polar circuit because your machine is equipped with a polar relay. Is that right?
My previous Model 15 which I ran for years had a polar relay installed but I simply never used it & drove the machine via a 60ma local loop to the selector magnets.  If I recall correctly, the terminal block has enough connections there to allow one to reconfigure the machine to use or not use the polar relay (and other features).
WayneWB4OGM

-----Original Message-----
From: Paul Birkel <pbirkel at gmail.com>
To: greenkeys at mailman.qth.net
Sent: Wed, Jan 27, 2021 3:54 am
Subject: [GreenKeys] M15 with Polar Relay -- Configuration

Good morning all;  I seek some guidance/experience with setting up an M15 that came equipped with a polar relay and otherwise essentially  “factory fresh” wiring harness.  My basic question is whether I can swap the relay for a non-polar one and then use the M15 “conventionally” … and if so, what would be the substitute relay?  And then … does anyone have such a substitute available for employment in this endeavor :->?  Alternatively, I do have another polar relay and definitely have more than a “passing interest” in leaving the M15 as received and instead setting up a local polar circuit to drive it that would in turn be patched into a normal local loop.  There’s not been much discussion of practical setup/employment of polar circuits here AFAIK; I enjoyed reading the AT&T Long Lines book on “Principles of Electricity” back in 2019 and intend to refer to it again before I proceed.  I originally received the M15 from an ex-MARS guy who eventually used it as an office printer with an early microcomputer system before putting it into storage a few decades ago.  He kept it well lubricated, thank goodness.  It appears to be configured using a standard 60 mA pulling magnet (no S/P switch nor a 3-position terminal block; the rangefinder does NOT have an HM marking; and the magnet definitely has round windings).  I haven’t yet checked the resistance on the loop to be triply sure.  My main terminal block appears to be physically different from that shown at http://www.baudot.net/gil/tty-machines/pics/M15-KSR-Gil-Iface-Terminals.jpg  I don’t know whether that’s significant.  It appears to be configured to separate the KBD from the PTR circuits.  The M15 wiring appears to be entirely original excepting one modification at the polar relay – which is a coaxial-cable stub (clipped off after ~2” and left hanging) attached to the rearmost pair of polar relay terminals that appear to have been otherwise unused (but can’t quite be sure of that, although there are no telltale snips that I can spot).  Possibly that’s a remnant of the earlier MARS use, and the separated KBD/PTR circuits reflect the later office-printer use.  Possibly the use a M15-polar configuration is documented in some RTTY publication?  At the moment I’m using the “New RTTY Handbook” as my starting point, but I imagine that there are other specific how-to articles …  Your various and sundry thoughts and observations will be much appreciated, thank you.  Good Health to You and Yours,paul      ______________________________________________________________
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