500 series receiver cords

[Babybearjs]

I was noticing that on the first generation WE 500 series desk sets, they came with straight cords... do these even exist anymore?.... I can get plenty of the cloth cords for the 300 series, but for the 500 series, they used vinyl. what is the history of these cords and is there anything made today to keep these phone original?  Or, were these a 1 time limited edition release?

[RotarDad]

The straight cord on the 500 was standard issue from introduction until '57 I believe.  Coiled cords were always optional, but became standard in '57.  Not only on black sets, but colored sets also (grey or color-matched, depending on phone color).  The black cords were rubber, and many have rotted by now, and they tended to fail at the restraint by the handset.  They were often replaced with coiled cords, and are not reproduced.  They are not rare in black, but are hard to find in on a phone in nice condition.   There are several good 500 history threads here, discussing these in detail.

[Greg G.]

I have heard of collectors making straight handset cords out of line cords.

[Phonesrfun]

I guess if you could find the handset-end boot, that would work.  That and the fact that the wire colors in a line cord are red, green and yellow, and a 500 set used red, black and 2 whites.  The red and one of the whites can be connected together as a common, so a three wire handset cord would work perfectly well regardless of colors. 

I once read the reason why WE went to 4-wires in the G style handset.  It was part of getting the most optimum performance of the antisidetone and click supression, but seemed to be overkill.  I have used three wires in a 500 and my limited hearing discernment could not tell any difference.

Does anyone have any examples to show of a handset cord made from a line cord?  The old neoprene covered cords with rubberized wires inside were prone to the rubber getting very brittle.  The neoprene boot would likely outlive the rest of the cord by a long shot.

[RotarDad]

I believe that all of the straight 500 handset cords have the boot molded in.  If that is true, then salvaging that part would be very difficult.  500s with a decent straight cord show up fairly often on Ebay - it might be easier to wait for one of those.

[poplar1]

Wasn't the original reason given for the 4th conductor that it would extend the life of the handset cord? That is because there would be no DC in the added white wire going from R to the receiver.

[Phonesrfun]

Poplar1:

I went back and found the thing I read.  It comes from a Q&A the Bell Labs released in 1949 titled "Transmission Characteristics of the New Telephone Set"  W.C Jones.  It looks like your recollection is more accurate than mine:

[andre_janew]

I recall reading that D/P made a handset cord for his 500 series field test phone.  He used a cord with four wires.  The colors were red, green, white, and black.  He painted the green wire white so that he would have red, black, and two whites.

[Babybearjs]

you know its funny....they added the 4th conductor yet the red and one of the white wires are still connected together on the "R" terminal essentially making the cord a 3 conductor....

[Dan/Panther]

Andre_Janew Wrote; "I recall reading that D/P made a handset cord for his 500 series field test phone.  He used a cord with four wires.  The colors were red, green, white, and black.  He painted the green wire white so that he would have red, black, and two whites."

EXACTLY.


I needed one for my field trial 48 set. I used a straight handset cord, from an AE I believe it had 4 colored wires which were Green, Yellow, Black, and Red. What I did was spray paint the Green and Yellow wires white. With the Rustoleum plastics paint. The I used apiece of black rubber tubing, which I shaped to size at low speed in a drill press. I put a couple drops of Superglue on the inside of the tube, and slid the AE handset into the tubes.
Here are a couple pictures, not perfect, but very close.
Hope this helps some.
This method makes a very fresh and flexible Handset cord. The ones on eBay are for the most part cracked at the end fitting, and most are curves at the end, and brittle.


D/P

[Phonesrfun]

I still envy that find.

[Phonesrfun]

you know its funny....they added the 4th conductor yet the red and one of the white wires are still connected together on the "R" terminal essentially making the cord a 3 conductor....

Refer to the excerpt from the Bell Labs announcement posted earlier.

The important thing is that the common point (R terminal on the network) is before the cord, and not up in the handset on the R terminal in the handset itself.  You might need to draw a diagram to see it because it isn't drop-dead obvious. 

In the old style 3-wire cord the red common wire is the return for both the transmitter which carries DC and the receiver which carries a very small AC voice signal and no DC.  If either the red or black transmitter wires become partially faulty and "noisy" due to broken strands, then the receiver side of the circuit will "hear" these noises due to the fact that the red wire is a common to both receiver and transmitter.

With the four wire cord, a partial fault in the red or black transmitter wires, the receiver will not be as effected.  This is because the common point is at the network.  Yes it is also in the handset with perfect cords, but with imperfect cords the common is still at the network and not in the handset.

[unbeldi]

you know its funny....they added the 4th conductor yet the red and one of the white wires are still connected together on the "R" terminal essentially making the cord a 3 conductor....

Refer to the excerpt from the Bell Labs announcement posted earlier.

The important thing is that the common point (R terminal on the network) is before the cord, and not up in the handset on the R terminal in the handset itself.  You might need to draw a diagram to see it because it isn't drop-dead obvious. 

In the old style 3-wire cord the red common wire is the return for both the transmitter which carries DC and the receiver which carries a very small AC voice signal and no DC.  If either the red or black transmitter wires become partially faulty and "noisy" due to broken strands, then the receiver side of the circuit will "hear" these noises due to the fact that the red wire is a common to both receiver and transmitter.

With the four wire cord, a partial fault in the red or black transmitter wires, the receiver will not be as effected.  This is because the common point is at the network.  Yes it is also in the handset with perfect cords, but with imperfect cords the common is still at the network and not in the handset.

I think a practical example of the virtue of four conductors, or better the non-virtue of three, was the first generation of three-conductor coiled rubber cords for the 302 sets in ca. 1949.  Many of these cords are noisy with static, at least by the time we find them today. Later 3-conductor cords were much better.  While this doesn't really 'explain' the reason for using four conductors, it illustrates the problems that can result from having a current carrying common conductor for transmitter and receiver.  This may especially be true when the individual conductors are reduced in thickness, as they were from the 300- to the 500-series sets.  The four-conductor 500-series cords have a smaller diameter than the three-conductor 300-series cords.

That said, I do remember reading the passage in the conference proceedings, and whenever I come across it again, I cannot help to get the impression that they didn't really have a good explanation for the fourth conductor.  It seemed to me that they had some kind of cord problem they didn't want to talk about, which the fourth conductor solved.

But we should also remember that in some handset applications they in fact needed to have the fourth conductor. Previously, they stocked a separate cord type for those handset.  Perhaps they wanted to get out of the business of maintaining stocks of many different cords to reduce overall cost, just like they did by using a 'modular' combined network, reducing the number of discreet parts to stock.

[Dan/Panther]

I still envy that find.

Bill;
Every timer I walk past it, I can't help but stop and look at it.
D/P