Improvised subset for 50AL desk stand using 101A coil

[Dennis Markham]

You're absolutely right, Terry.  There are entries on that site that are duplicates because of incorrect spelling.  My apologies to Charlie and others for taking this off topic from Charlie's 50AL desk stand.  I suppose since his phone has the SCHENECTADY card it's what caused us to go in that direction. 

We could do a topic on the TenProject exchange and exchange cards, if we haven't already.

[AE_Collector]

We could do a topic on the TenProject exchange and exchange cards, if we haven't already.

I was thinking that too. I will do some searching on the forum for ten project.

We now return you to the previously scheduled phone discussion.....

Terry

[poplar1]

I have a 50AL desk stand which has been in my attic for years. I wanted to try it buy don't have a subset so I improvised one using some 302 phone parts: a 101A coil and a capacitor.

Here's how I hooked it up-

From the desk stand: red wire to R, green wire to GN and yellow wire to Y (L2) on the coil. From the capacitor: red wire to C, black wire to Y (L2). Then I hooked a line cord with modular connector to L1 and L2.

Everything seems to work fine. I can dial, talk and hear okay. Just wondering if this wiring and combination of parts makes is a reasonable and proper way to hook up the desk stand? Thanks.

Yesterday I received an update to this--dated 1942!

In the previously discussed circuit, the black condenser wire is moved to Y/L2. This should be used only on "individual lines without extensions," but it does provide an anti-sidetone circuit using a sidetone only candlestick such as a 20AL, 50AL, or 51AL.

it is also possible to use an anti-sidetone subset (634A, 684A or 302 base) without this restriction on extensions. However, now you have the equivalent of a sidetone circuit even though the subset or 302 base was originally intended only for anti-sidetone. This is accomplished without modifying the original wiring of either the phone or the subset:

Connect Yellow (desk stand cord) to GN on the 101A induction coil.
Connect Red  to L2/Y on the 101A.
Connect Green to BK terminal (or spare GND terminal in a 302 base), (This is the same terminal that has the black condenser wire.)


EDIT: However, it is necessary to make the following changes in the 302 base (or 634 or 684 subset):

Move red capacitor wire  from C to L1
Move ringer wire and line wire from L1 to C

>>Connect incoming line to C and L2Y>>



Reference:
Bell System Practices
Station Installation and Maintenance
WR-C63.373
Issue 1, 9-30-42
AT&T Co

(This is a section on blue paper that was issued during the war when there were shortages of equipment.)