[GreenKeys] Western Electric Model 15B Main Line Telegraph Sounder, 1875-1900

[Roy Morgan]

I have one of these:
Mainline Sounder 15B
Marked "30 Ohms"

I have read that often these were run by a local battery switched by a "sensitive relay" in the main telegraph line. 

It seems like this 30-ohm coil would be in series with the main telegraph line, and coils of higher resistance would be used with a local battery and relay in the line. 

Anyone have more information!

(Asking prices for these seem to range from $80 to $130! This one is not collector quality but with work would clean up nicely.)

Thanks. 
Roy

https://www.thehenryford.org/collections-and-research/digital-collections/artifact/388676#slide=gs-300550


Roy Morgan
K1LKY Western Mass
K1LKY68 at gmail.com