WECo 101A and 104A Induction Coils

[G-Man]

Not wanting to beat a dead horse; instead, the following jpeg is intended to illustrate the electrical and other differences between 101A and 104A induction coils.

[unbeldi]

The electrical differences are actually misrepresented in these diagrams, because they imply an incorrect phase relationship between the winding.
The usual, older drawings of the coils by Western Electric in most circuits correctly depicts them, even though they never actually mark the points of equal phase as  has been customary in electronics for a long time.

[G-Man]

Here is another induction coil from the 10xx-series. I am adding it to further illustrate their electrical differences. Please note that these drawings were originally presented by Western Electric to assist repairmen by showing representative diagrams and resistances in a plain, simplified manner.

[Babybearjs]

notice how all 3 windings are connected together in the 101 series diagrams.... and how the 104 has a divided coil.... by putting the jumper that's under the "C" terminal across "C" and "BL" it basically turns it into a 101. this is what I had to do with my 307's... by doing this, and making some other minor changes the 307 does not need a 3 volt battery supply and can be used on a common battery circuit. (and, yes.... it can always be changed back....)

[unbeldi]

No, it doesn't turn it into a 101.
And doing so does not make it equivalent for use as a common battery instrument.

[Babybearjs]

but it works....

[Phonesrfun]

but it works....

"works" might be a relative term.  The winding impedances are entirely different between the two coils, so on a common battery line, there probably isn't any sidetone reduction and the volume you hear in the receiver is probably not optimal.

[Babybearjs]

with the new digital CO equipment, Sidetone, and anti-sidetone don't seem to matter anymore...I have several 307's that I have wired this way and the 104 coil works just fine.... I think the extra induction coil helps too... I know that the phone company used to change out the coil to a 101A, disconnect and store the extra induction coil (or even remove it completely) and tape off the extra cap circuits. they would just basically convert the unit over to a 302 instead of a 307.... I found 1 of my phones was that way and a changed it back...

[tanderson78]

I wonder if anybody on this thread can help me.  I picked up a Western Electric 5302 at a thrift store  last year and finally got around to tinkering with it.  I had no tone and swapped out the 101A with a spare 101B induction coil with instructions from an expert and finally got tone.  Then I determined I had ringer problems.  I hooked up the ringer to a working 302 and the ringer worked fine.  I figured I needed a new capacitor, which I purchased on ebay.  Its tough to tell the difference between Yellow or Slate but I have swapped them around and still have no luck with the ringer.  I even have a second capacitor I can try.  Any suggestions for a ringer that worked in a 302 but isn't working in a 5302?

[poplar1]

5302 or 302 with 101B:

On the 101B, you can connect the red line cord lead and the red ringer wire to RR, because RR on the 101B is the same as L1 on the 101A.
The slate capacitor wire and the black ringer wire are on K.

But you can't connect anything to M terminal on the 101B. You will still need to connect the green line cord lead to the yellow capacitor wire + the yellow hookswitch wire. Not sure that they will all reach the only remaining blind terminal: GND. (Or, you can cut the soldered connection from M to the coil, thus making M a blind terminal for connecting the green and the 2 yellow wires.)

[Alex G. Bell]

On the 104A, you can connect the red line cord lead and the red ringer wire to RR, because RR on the 104A is the same as L1 on the 101A.

The slate capacitor wire and the black ringer wire are on K.

But you can't connect anything to M terminal on the 104A. You will still need to connect the green line cord lead to the yellow capacitor wire + the yellow hookswitch wire. Not sure that they will all reach the only remaining blind terminal: GND. (Or, you can cut the soldered connection from M to the coil, thus making M a blind terminal for connecting the green and the 2 yellow wires.)

Did you mean 101B rather than 104A?

[poplar1]

Did you mean 101B rather than 104A?

Yes---just made correction