Western Electric D97464 (field trial 302) project

[andre_janew]

You could create the plungers out of wood or metal.  Purists would probably scoff at the idea that they be made of anything but plastic!  However, we are not talking about a production model here.  For all anyone knows, maybe wooden or metal plungers were used in the field trial 302s. 

[Bartonpipes]

Christian- If you have access to a metal lathe at a school or something you could create plastic (or even metal) plungers on that.

Taking metal shop at my school with a very trusting teacher who basically gave me the run of the shop was one of the best moves I ever made.

[WEBellSystemChristian]

Do you guys think that this condenser could be used on this phone? I was looking for a standard one to use, but this came up in the search. I know it's not identical, but it's similar to Robby's '36 condenser in his field trial set.

http://www.ebay.com/itm/391072672681

[rdelius]

It has to be a dual capacator .5uf and 2uf

[unbeldi]

The condenser you should be looking for is a type 194B.  It was a standard capacitor pack in the 1930s and was also used in the 634BA subset.

See here:  http://www.classicrotaryphones.com/forum/index.php?topic=13593.msg142217#msg142217

and here: http://www.classicrotaryphones.com/forum/index.php?topic=10361.msg110097#msg110097

[WEBellSystemChristian]

Okay, so I should look for a type 194B condenser. Anyone know the induction coil type? Was it only found on the D97464, or was it more commonly found in WE subsets? thought I saw one like that in a 634-type subset, but I think it was just a 302 induction coil that was used for an upgrade from the older coil it contained.

[unbeldi]

Okay, so I should look for a type 194B condenser. Anyone know the induction coil type? Was it only found on the D97464, or was it more commonly found in WE subsets? thought I saw one like that in a 634-type subset, but I think it was just a 302 induction coil that was used for an upgrade from the older coil it contained.

The induction coil is a standard 101A. Some of the early 101As are labeled only with the number, 101.  But you're probably not going to have much choice. Early 101-type induction coils were not type/date stamped on the insulation wrapper around the winding, but on the side of coil on the metal or on the cardboard winding core.

Of course, you've noticed that it is oriented still the proper pleasing way until production began, when they turned it 180º.  I believe they did this to avoid electromagnetic coupling of the coil with the ringer magnet.  Turning it, provided shielding as is easily seen.


PS:  There exists in electronic design a golden rule that says to position two transformers or inductors always with their axes of coil windings at right angle with respect to each other to prevent coupling.

[WEBellSystemChristian]

Okay, so I should look for a type 194B condenser. Anyone know the induction coil type? Was it only found on the D97464, or was it more commonly found in WE subsets? thought I saw one like that in a 634-type subset, but I think it was just a 302 induction coil that was used for an upgrade from the older coil it contained.

Of course, you've noticed that it is oriented still the proper pleasing way until production began, when they turned it 180º.  I believe they did this to avoid electromagnetic coupling of the coil with the ringer magnet.  Turning it, provided shielding as is easily seen.


PS:  There exists in electronic design a golden rule that says to position two transformers or inductors always with their axes of coil windings at right angle with respect to each other to prevent coupling.

Oh, that's what was confusing me! I thought that it was a completely different coil (it looks longer front to back) but that's just because it's on it's side!

Well, it looks like it shouldn't be very hard to find proper internal components. Everything except for the condenser, which certainly won't be difficult to find, but will prove more work to look for than a B1A ringer and 101A coil.

[andre_janew]

Your base is from a 1939 302.  Right now it is set up for a condenser that is newer than the 194B.  Do you have any idea what would need to be done to use the 194B in your current base?  I have no idea myself, but I suspect that more knowledgeable people could tell you.

[WEBellSystemChristian]

Your base is from a 1939 302.  Right now it is set up for a condenser that is newer than the 194B.  Do you have any idea what would need to be done to use the 194B in your current base?  I have no idea myself, but I suspect that more knowledgeable people could tell you.

My goal is to keep this phone as original as possible to a field trial 302. I want to use as early of a base as possible, but I can't find a '37 or a '36 base, so I have to use a '39. I'm trying to use parts that would of been on a D97464, and I use parts that are similar where original parts aren't available.

[poplar1]

The induction coil is a standard 101A. Some of the early 101As are labeled only with the number, 101.  But you're probably not going to have much choice. Early 101-type induction coils were not type/date stamped on the insulation wrapper around the winding, but on the side of coil on the metal or on the cardboard winding core.

Of course, you've noticed that it is oriented still the proper pleasing way until production began, when they turned it 180º.  I believe they did this to avoid electromagnetic coupling of the coil with the ringer magnet.  Turning it, provided shielding as is easily seen.


PS:  There exists in electronic design a golden rule that says to position two transformers or inductors always with their axes of coil windings at right angle with respect to each other to prevent coupling.

Actually, they didn't rotate the induction coils until about Sept., 1938. Ironically, they never changed the orientation of the terminal désignations or the "101A" and date stamps, so they appear to be upside down in all the late '38 through 1954 sets.

[unbeldi]

The induction coil is a standard 101A. Some of the early 101As are labeled only with the number, 101.  But you're probably not going to have much choice. Early 101-type induction coils were not type/date stamped on the insulation wrapper around the winding, but on the side of coil on the metal or on the cardboard winding core.

Of course, you've noticed that it is oriented still the proper pleasing way until production began, when they turned it 180º.  I believe they did this to avoid electromagnetic coupling of the coil with the ringer magnet.  Turning it, provided shielding as is easily seen.


PS:  There exists in electronic design a golden rule that says to position two transformers or inductors always with their axes of coil windings at right angle with respect to each other to prevent coupling.

Actually, they didn't rotate the induction coils until about Sept., 1938. Ironically, they never changed the orientation of the terminal désignations or the "101A" and date stamps, so they appear to be upside down in all the late '38 through 1954 sets.

Yes, sorry.
I suppose it might have required retooling of the transformer production lines to change the stamps. But it seems to be the better orientation anyhow given the orientation of the L2-Y designation. 302s weren't the only devices that took a 101.

[Dan/Panther]

The set I handled had a tag stating return to  Bell labs for service.
Jim S.

Jim, Did your set say Bell Labs, or Murray Hill ?
D/P

[WEBellSystemChristian]

So, do you guys think I should rotate the induction coil, to make it look like the original '36s? Would that create electrical problems with the ringer magnet, as Unbeldi stated?

[unbeldi]

So, do you guys think I should rotate the induction coil, to make it look like the original '36s? Would that create electrical problems with the ringer magnet, as Unbeldi stated?

I thought you had already answered that question for yourself:
    My goal is to keep this phone as original as possible to a field trial 302.