[GreenKeys] M28ASR Wiring

[Sheldon Daitch]

 Also, in connection with 60mA loops, sometimes it was 62.5mA loop currents.

http://etler.com/docs/bsp-archive/E/E44.263_I3.pdf

Sheldon
    On Thursday, December 24, 2020, 01:35:14 PM EST, w9ddd at tapr.org <w9ddd at tapr.org> wrote:  
 

Now to muddy the waters.
How did we end up with two different values for loop current?  I can image early on it took 60 mA to the sounders.  Then as they got more sensitive a lower current would result in extended battery life. I also read references to 30 and 65 mA loops.  30 would seem to be more logical for series connection than 20.
I have always removed line relays from 28 KSR/RO LESUs on the theory that it's an additional point of failure.  Amateur literature seems to center on 60 mA loops, so that's what I've always used.  The TU-170 is designed to provide 60 mA only.  And the default for others seems to be 60.
Now when it comes the ASR I was kindly gifted I haven't decided for sure, but I will probably leave the line relay it because it's tightly integrated into a circuit that allows printing local copy while punching tape.

John, W9DDD


  
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/greenkeys/attachments/20201224/192a9673/attachment.html>