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A Couple of WE Subsets

Started by LarryInMichigan, July 15, 2016, 03:02:14 PM

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LarryInMichigan

I went to a very crowded estate sale today and bought a bunch of stuff.  Two of the items were WE subsets: a 554-AR and 295 A.  I paid $7 for the 554-AR and $17 for the 295 A.  I have been able to find some information about the 295 A, but I cannot find anything about the 554-AR.  What was its purpose?

Thank You


Larry

poplar1

The 554-AR is the forerunner of the tube sets such as 634AT subset or 306 desk set. Both the relay and the tube serve the same purpose.
These all are for 4-party selective, or 8-party semi-selective party lines. Either positive or negative superimposed ringing is sent over either tip or ring.
"C'est pas une restauration, c'est une rénovation."--François Martin.

LarryInMichigan

Quote from: poplar1 on July 15, 2016, 03:20:38 PM
The 554-AR is the forerunner of the tube sets such as 634AT subset or 306 desk set. Both the relay and the tube serve the same purpose.
These all are for 4-party selective, or 8-party semi-selective party lines. Either positive or negative superimposed ringing is sent over either tip or ring.

I figured that it was something like that.  I have an older wood subset somewhere which is similar.

Thank You


Larry

unbeldi

#3
The 554 sets are very similar to the 534s, but have a second capacitor added to the round up of parts.

The AR version added a relay to operate the ringer.

The 554-AR would typically be used with a 51AL or a B1/D1 set for sidetone operation on four-party selective service.

It enabled the first fully selective four-party service, other than the poorly performing harmonic system earlier, achieved by the combination of divided (i.e. two-party) ringing with additional selection by reversing superimposed battery polarity with biased ringers.

The problem with the relay system was that when the operator selected any of the four stations, sending ringing current, the relays in all sets operated, each applying ground to the ringer, and therefore current flowed in multiple ringers, rather than just the selected station.  In fact current flowed in four relay bridges, and two ringers in every case. Thus this system required quite a bit of ringing power and was limited to shorter lines than a conventional party line permitted.

The system was greatly improved with the 313A electron tube in the mid 1930s.  It reduced the component count and cost, required no adjustments, and current flowed in only the selected ringer. It thus permitted longer loops for four-party service.  It also eliminated bell-tapping.

For anti-sidetone service, the successor to the 554-AR was the 634-AR. The first tube set I think was the 634-AT. I don't recall seeing references to any sidetone tube sets (534-AT ?)

The 634-AR already had the second capacitor, so the designation 654-AR did not need to exist.

unbeldi

Here is a circuit of the 554-AR with a D1/102 desk set, from my studies.
The separation between subset and deskset is given by the terminals R,GN, Y  for the mounting cord.