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I own it...What is it??

Started by Doug Rose, December 23, 2014, 06:21:34 PM

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When you look at the resistances/impedances of the induction coil you'll notice an extremely high ratio between line side and inside (RX+TX).

150Ω (line side) vs 2Ω+11Ω (inside) in the set on eBay, mine is 144Ω vs. 3Ω+14Ω, so the ratios are on the order of 10, while a typical PSTN telephone subscriber instrument would be quite below that.
It should be interesting to measure Doug's set, but I think it would be similar.


Here is another similar set by Western Electric:
It's a (1)293A.  In the 1922 RR catalog these type of instruments are referred to as Siding Sets.