[GreenKeys] M15 optional relay?

[Duncan Brown]

Steve,

The polar relay was to isolate the local loop from the signal loop 
(which, in the land-line days, could be many miles long).  The polar 
relay also would clean up distortion on the signal line.

When operating a TTY from a FSK converter or modem, the polar relay is 
not needed and the TTY's selector magnet can be wired directly to the 
FSK converter's loop.

There may be times when operating multiple machines, that a polar relay 
is helpful, which is why most M28 machines still use them.

In the US Army, c1950-80, the Kleinschmidt machines almost never used 
polar relays.

So don't worry about the polar relay socket, just wire the selector 
magnets into your loop (with sufficient resistance to set the loop 
current - typically 60 ma. for the M15).

Have fun,

Duncan Brown, K2OEQ
USASA    31J30

Antique Wireless Association
  Communication Technologies Museum
    Asst. Curator, Commercial Equipment
(also chief TTY op & repairman)

i-Telex: 212503

www.antiquewireless.org
AWA Youtube channel: 
https://www.youtube.com/channel/UCX55peBhzeX1qps_VYXdLBA





On 1/15/2025 1:06 PM, steve bennett via GreenKeys wrote:
> John,
>
>   In the video Mark mentions polar relay but he says it optional.
> He does not explain.
> When would you need to use it?
>
> Thanks,
> -Steve
>
> On Wednesday, January 15, 2025 at 12:21:55 PM EST, John, W9DDD 
> <w9ddd at tapr.org> wrote:
>
>
> That is the bracket with socket for a line (polar) relay. Relay not there.
>
>
> On 1/15/2025 10:51 AM, steve bennett via GreenKeys wrote:
>> GKs,
>>
>>  What is the purpose of this relay shown in the Curious Mark video?
>> Inline image
>>
>> -Steve
>>
>>
>> ______________________________________________________________
>> GreenKeys mailing list
>> Home:http://mailman.qth.net/mailman/listinfo/greenkeys <http://mailman.qth.net/mailman/listinfo/greenkeys>
>> Help:http://mailman.qth.net/mmfaq.htm <http://mailman.qth.net/mmfaq.htm>
>> Post:mailto:GreenKeys at mailman.qth.net <mailto:GreenKeys at mailman.qth.net>
>>
>>>>> Jordan Spencer Cunningham's GreenKeys Search Tool:https://teletype.net/gksearch <https://teletype.net/gksearch>
>>>>> 2002-to-present greenkeys archive:http://mailman.qth.net/pipermail/greenkeys/ <http://mailman.qth.net/pipermail/greenkeys/>
>>>>> 1998-to-2001 greenkeys archive:http://mailman.qth.net/archive/greenkeys/greenkeys.html <http://mailman.qth.net/archive/greenkeys/greenkeys.html>
>>>>> Randy Guttery's 2001-to-2009 GreenKeys Search Tool:http://comcents.com/tty/greenkeyssearch.html <http://comcents.com/tty/greenkeyssearch.html>
>> This list hosted by:http://www.qsl.net <http://www.qsl.net>
>> Please help support this email list:http://www.qsl.net/donate.html <http://www.qsl.net/donate.html>
>> Message delivered tow9ddd at tapr.org <mailto:w9ddd at tapr.org>
>
> -- 
> ---
> ----
> The above comments or recommendations are SWAG. Use at your own risk.
>
> John, W9DDD
> ______________________________________________________________
> GreenKeys mailing list
> Home: http://mailman.qth.net/mailman/listinfo/greenkeys
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:GreenKeys at mailman.qth.net
>
> >>> Jordan Spencer Cunningham's GreenKeys Search Tool: 
> https://teletype.net/gksearch
> >>> 2002-to-present greenkeys archive: 
> http://mailman.qth.net/pipermail/greenkeys/
> >>> 1998-to-2001 greenkeys archive: 
> http://mailman.qth.net/archive/greenkeys/greenkeys.html
> >>> Randy Guttery's 2001-to-2009 GreenKeys Search Tool: 
> http://comcents.com/tty/greenkeyssearch.html
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to raleigh_ranger at yahoo.com
>
> ______________________________________________________________
> GreenKeys mailing list
> Home:http://mailman.qth.net/mailman/listinfo/greenkeys
> Help:http://mailman.qth.net/mmfaq.htm
> Post:mailto:GreenKeys at mailman.qth.net
>
>>>> Jordan Spencer Cunningham's GreenKeys Search Tool:https://teletype.net/gksearch
>>>> 2002-to-present greenkeys archive:http://mailman.qth.net/pipermail/greenkeys/
>>>> 1998-to-2001 greenkeys archive:http://mailman.qth.net/archive/greenkeys/greenkeys.html
>>>> Randy Guttery's 2001-to-2009 GreenKeys Search Tool:http://comcents.com/tty/greenkeyssearch.html
> This list hosted by:http://www.qsl.net
> Please help support this email list:http://www.qsl.net/donate.html
> Message delivered toduncanancy at earthlink.net
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/greenkeys/attachments/20250115/56a987bd/attachment.html>