[GreenKeys] Model 19 and 15 on 20mA loop?

Tue Apr 12 20:50:15 EDT 2016

That's what was confusing me too Wayne, after reading a 1944 Teletype manual and I think the 255 polar relay was used for that....Right? 

But then I read a later 1954 manual and it mentions using a "selector driver" which looks like a power supply used to boost a 20mA loop current to 60mA instead of using a relay. 

The keyboard thing was my next question! Ha...Ha! That also is confusing. 

Andy 
KD8JXK 

----- Original Message -----

From: "drlegendre ." <drlegendre at gmail.com> 
To: "Wayne Hall" <hwhall at compuserve.com> 
Cc: "Green Keys" <greenkeys at mailman.qth.net> 
Sent: Tuesday, April 12, 2016 8:09:30 PM 
Subject: Re: [GreenKeys] Model 19 and 15 on 20mA loop? 

While this is being discussed, could someone comment on the 20/60mA 'conversion' for the keyboard on later M15 units? 

As I understand, it's related to the need for sufficient current to keep the KB contacts clean? Or possibly to prevent over-current of the contacts? Can't recall at the moment. 

On Tue, Apr 12, 2016 at 6:55 PM, < hwhall at compuserve.com > wrote: 

Ye p, you're right. It apparently was the holding magnet that could be rewired for either 60 or 20 ma. Also confusing my memory was a reference to the changing the Line current setting which when using the polar relay could be either 60 or 20 ma by changing an resistor connection. 

Wayne 
WB4OGM 

-----Original Message----- 
From: WA5CAB--- via GreenKeys < greenkeys at mailman.qth.net > 
To: greenkeys < greenkeys at mailman.qth.net > 
Sent: Tue, Apr 12, 2016 5:17 pm 
Subject: Re: [GreenKeys] Model 19 and 15 on 20mA loop? 

No. The selector magnets in the pulling selector are already wired in series. I was pretty sure that this was the case but I dug out the first Teletype manual I ever owned (nust have been in early 1968 as I had written my two call signs and "ETN" on the front cover) and waaaaay back in the back found the schematic diagram. 

Robert Downs - Houston 
wa5cab dot com (Web Store) 
MVPA 9480 

In a message dated 04/12/2016 11:02:50 AM Central Daylight Time, magwheels at comcast.net writes: 

<blockquote>
I see here that if you have the holding type selectors the change is easy to make from 60mA to 20mA. 

But could the pulling type magnets also be used at 20mA loop current? 

73 

Andy 

______________________________________________________________ 
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 

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 hwhall at compuserve.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 

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 drlegendre at gmail.com 

</blockquote>

______________________________________________________________ 
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 

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 magwheels at comcast.net 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/greenkeys/attachments/20160413/2eff3180/attachment.html>