I wrote this a while ago, and have gotten it to a point where I can post it here. Dennis Markham was kind enough to proof it, and my original writing combined the 102/202 topic with the topic of subsets and was too long. This is even kind of long, but is shorter than it was. I think Dennis was talking about making this a sticky topic that can be used for reference rather than a thread. However, before it does become a sticky topic, I would surely welcome additional comments or suggestions, and or maybe technical corrections to dates. My bibliography was mostly from memory, but also from Ralph Meyer's book "Old-Time Telephones! Design, History, and Restoration", and from Larry Wolff's Book "Desk Telephones of The Bell System The years 1875 to 1955"
Here it is:
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What is the difference between a 102 and a 202?
Many people come into the hobby trying to learn about some of the early Western Electric telephone models. The earliest handset models for Western Electric were called "desk sets" and they had to be matched up with a "subset" (Subscriber set) in order to function. The combination of the desk set and the subset is what made the complete telephone.
The desk set usually sat on the desk and had a felt or leather covered bottom. It consisted of just the body called the "mounting", the handset, a dial (if it were for dial service), and the switch that is activated by taking the handset off the cradle. Other than the handset cord and the cord that connects the desk set to the subset, that is all there generally went into a desk set. Sometimes there was a couple of additional items connected to the dial to prevent interference to nearby radios sometimes caused by the dial pulses emitting radio frequency interference.
The body or "mounting" of these early desk sets had a letter designation. The "A" or "A1" mounting was the first ever handset and cradle model Western Electric produced. It was only made for a year or so around 1927. Its base was round, and resembled a candlestick base in its construction. Not only were they made for a short period of time, but few were made, and many were used in test environments to test the new concept of a handset in the USA. These tend to be very pricey due to the relative scarcity of them. These would be correct with the early E1 handset which would have had the seamless handle and seamless handset caps, but would have also had the early "bullet", or barrier button style 395A transmitter.
In 1928 or so, Western Electric replaced the A1 mounting with the slightly more streamlined B1 mounting. Its life went for about 2 years until about 1930. In the meantime, many of these were made, and are not uncommon items on E-Bay. These also had a round base, and originally would have come stock with the same handset as the A1 model. Both the A1 and the B1 would have come originally with a #2 dial that has the finger stop mounted to the side of the dial. The dial mounted on the surface of the desk set mounting and was not recessed.
From about 1930 until 1938, the model being produced was the "D1" mounting. It has an elliptical base, the dial mount is in a recess, and the dial needed is a #4 which does not have the dial finger-stop mounted externally. It has a slightly lower profile and height than the B1 mounting, and the elliptical bas made for more stability while dialing. This base had a more flush dial mounting due to the recess. It would probably have been equipped with an E1 handset with seams along the side, and around the receiver and transmitter caps. The handset would have contained a much improved F1 transmitter element retrofitted to fit in the E style handset. Later models of the D mount, and even some B mounts were retrofitted in the field or in the refurbishing shops with complete F1 handsets in the late 1930's
So, why all this talk of A, B, and D mountings. What about 102 versus 202?
The 102 versus 202 designation has nothing to do with a model of the phone body itself or the way it looks. 102 simply means that the desk set was connected to a sidetone subset, and a 202 was connected to an antisidetone subset.
What is sidetone and what is antisidetone?
Sidetone it the term given to the fact that when you talk or blow into the transmitter, you can hear your own voice in the receiver. Some sidetone is good, but too much is detrimental to carrying on a comfortable conversation over the phone. Users of sidetone phones would naturally lower their voice, which would cause problems on connections over longer distances from the central offices. Sidetone sets were also a problem in noisy environments, like a factory or a busy office. Too much local noise would come back into the local receiver and make it hard for the person to hear the person on the other end.
Antisidetone circuits were developed in the late 1920's and rolled out in the 1930's. They are completely a function of the subset and not the mounting. Therefore, the B1 and D1 mounts could be connected to either subset type.
The circuit designation for sidetone was 102 and the designation for antisidetone was a 202 circuit. That is where the 102 and 202 designation comes from.
Why do people on E-Bay and others commonly refer to the round-based B1 mounting as a 102 and an elliptical D1 mounting as a 202? I feel that most of the B1 mountings when first placed in service were connected to sidetone subsets, and most later D1 mountings that came out at about the time antisidetone came out were just associated with the 202 type subsets by default. Besides, the difference in physical appearance makes for kind of a convenient visual differentiation.
Next, a discussion about the subsets.
Nice to see I'm not the only one who makes long posts : - ) Excellent job there.
Proofread: typo: paragraph beginning "From about 1930.." search for the word "bas" that should be "base."
Re. Sidetone: Feel free to use this wording if you like: "Sidetone is audio such as speech from your transmitter that is heard in your own receiver. One way to hear this is to blow gently into your transmitter and listen for the noise in your receiver. If there is too little or no sidetone, the phone sounds "dead" and you are likely to talk loudly. With too much sidetone, you hear your own speech so loudly in your receiver that you are likely to speak quietly, in some cases too quietly to be heard. Just the right amount of sidetone makes the phone sound "live" but not too loud, so you are likely to speak at the right volume to be heard clearly."
---
Why I used the terms 102 and 202 indiscriminately until I hung out here a while:
First phone I ever had was a 500 set. Then I ran into the 302 but initially thought of it as a "300" by way of similarity to 500. Then I learned that the correct designation was "302." Then I found the D1 referred to as a 202, and the B1 referred to as a 102, and those numbers stuck in my head because they seemed the logical predecessor to 302.
So the numbers 102 and 202 are "contagious memes" that I think propagate due to their similarity to 302. And the way to fix that is simply for enough of us to say B1 and D1, and use the terms correctly, that those memes propagate until the incorrect usages dwindle.
Bill,
Excellent topic!
Since this will be a reference, it's worth the time to check the BSPs for nomenclature. As I recall, the Bell System was somewhat obsessive about using "desk stand" for the upright phones with separate receivers we commonly call candlesticks and "hand telephone sets" for early phones that used handsets. Did they also use "desk set?"
The "hand set mounting" was the part of the set that held the handset, and in this case was marked with a code beginning with A, B or D. Note that there was a number after the letter to indicate a variation -- up to at least D10.
You probably want to avoid the complexity of describing each variation, but can refer to the styles as A Type, B Type or D Type, rather than using the most common variation (A1, B1, or D1). Your comments on sidetone versus antisidetone apply equally to all variations.
A wrap-up sentence could include the notion that due to the ambiguity of the terms 102 and 202 collectors prefer to use the hand set mounting code when describing the physical appearance of the phone.
[I just did a quick check of some of the BSP index documents to confirm the above --
C12.101, IC and 502-000-000, I34. Also see C38.323 I2 and C32.164 I1.]
All,
This is a great thread and I learned a lot from it, which is why I joined this forum in the first place. Until now, I had no idea what sidetone/antisidetone was but obviously just got a bit of education here.
I'm sure there is a thread here somewhere but can someone please direct me to what desktop sets match which subsets? I'm trying to learn this as I am restoring my first phone but want to expand past the phone that I am currently working on. I'd appreciate a point in the right direction.
Thanks.
Dan
Dan:
That is a good question, but I don't think there is any right answer, at least not all the time. There were so many odd-ball configurations that an all-inclusive list would be difficult. One can kind of go based on the dates of the phones and whether they are sidetone or antisidetone and match the phone to an appropriate subset of the same time period.
Since subsets were mounted on the customer's wall, a subset used for a non-dial candlestick, may very well have been left in place when changed out for a dial desk set, and left that way for years and years.
Add to that complexity that two of the subsets, the 534 and the 634, which were large, heavy and had a metal cabinet were re-made as a 584 and 684 using smaller, lighter parts and a bakelite cover.
So, generally, one has to go based on the year.
According to Ralph Meyer's book, Western Electric subsets were introduced as follows:
295 Wooden, sidetone 1902 Used for any candlestick of the time.
334 Metal version of the 295 introduced in 1912 and used for the same phones
534 Slightly smaller somewhat improved circuit. Sidetone introduced in 1918 during the realm of the candlestick, but would have been used on the A, B, and D mount telephones connected as sidetone, and the 20, 40, and 50 series candlesticks
634 Antisidetone version of the 534 above, and indtroduced in 1930 when antisidetone circuits came to be. Same metal cabinet, and would have been used for the B and D mount phones connected as antisidetone and the 150 series candlesticks
584 A smaller and lighter, more streamlined version of the sidetone 534. Introduced in 1930, presumably as a retrofit for older sidetone phones needing a new subset.
684 An antisidetone version of the 634 introduced in 1930, and an equivalent but smaller circuit as the 584. Used for the B and D mounts and 150 series candlesticks.
Other uses of subsets would have been for the space savers and pay phones, and were made well after the 302 was introduced in 1938 which eliminated the need for subsets in most cases. The 685 subset which is based on 500 technology using the 425B network was highly used in payphones of the 50's and 60's.
It should be noted that a sidetone phone can be connected to an antisidetone subset, but the phone will still function as a sidetone phone. An antisidetone phone can be connected to a sidetone subset, and the extra black wire simply taped and stored. This will also function as a sidetone phone.
I think this is an area where us as collectors have some leeway in choosing a subset to mate with the phone, and other that getting it correct as to the period, there are no hard and fast rules to observe. This is consistent with how these were connected and serviced at the time. During those years, and particularly through the depression, the phone company was likely to connect a phone to any subset that worked.
All of this is my opinion, of course.
QUESTION! ???
Let's say there is no mounting cord and you have to get one. How can you tell whether you're looking at a 102 or 202 by looking at the wiring in the desk stand? What is electrically different other than the mounting cord and the subset?
There is no difference between the 102 and the 202 inside the desk set of a B1 or a D1. Desk stands are only candlesticks. Anyway, on the B1 and D1, the only difference is the mounting cord and the subset to which it is connected. See the diagram here:
http://www.telephonecollectors.info/index.php?option=com_docman&task=doc_details&gid=2141&Itemid=27
Notice that for 202 operation, there is a black mounting cord wire connected to BK on the dial, and also connected to terminal BK in the 634 or 684 subset.
So, if you have an antisidetone subset, and you need to get a cord, get one with 4 conductors for antisidetone.
-Bill
I am completely blown away. Thanks. :o
Wow.
Are the circuit diagrams available somewhere, so we can compare them?
diagrams for the telephone sets or the subsets?
So, am I correct in assuming that if you have a D1/584 you cannot change that subset to be anti-sidetone even if you use a 4 conductor mounting cord?
Is sidetone really that bad when compared to anti-sidetone?
BDL, Maybe I don't understand your question but a 584 IS an anti-sidetone subset.
Doug Pav
It is? From the way I read Bill's post, I was under the impression it was not.
"584 A smaller and lighter, more streamlined version of the sidetone 534. Introduced in 1930, presumably as a retrofit for older sidetone phones needing a new subset."
Well, if that's the case, then I am a happy guy!
K
Oops, I think that I was talking out of the wrong orifice that early in the morning. Sorry to mislead you. To try to answer your question again, you can not make a sidetone set into an anti-sidetone set just by rewiring it. You would need to change the induction coil. You need a 3 wire cord for sidetone and 4 wire cord for anti-sidetone. For anti-sidetone you would need a subset that starts with a 6 like a 684. Go here to see the different wiring diagrams.
< http://www.classicrotaryphones.com/forum/index.php?topic=784.0 >
Sorry to get your hopes up.
Doug (mud) Pav
Bummer -- no harm, no foul.
Regardless, the phone does not matter, the subset does, right? So if my D1 was originally set up as a 102 (sidetone), I can change it to a 202 (anti-sidetone) just by changing the subset, right?
Here is the link to the eBay win. I'd post pix, but you can't take pix of eBay easily.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=150640871681&ssPageName=STRK:MEWNX:IT
Any opinions or information would be greatly appreciated.
Thanks for the clarification.
Don't worry about the sidetone, I have a B1/102 hooked up to a WE 534 subset and with me being a little hard of hearing, I liked it. If you want to get a new cover for your subset there is someone that makes them for $25. When the time comes let me know and I will find his email address.
Doug Pav
The subset in the auction appears to be anti-sidetone. Even though it's marked "584," which is a sidetone subset, the induction coil is the anti-sidetone coil. So it may have been altered to make it anti-sidetone at some point in it's life.
It's a nice early one, too, from March, 1930. Surely that must be very early for the bakelite-covered subsets.
;D ;D ;D
Quote from: bingster on August 09, 2011, 01:01:51 AM
diagrams for the telephone sets or the subsets?
Sorry, I missed your reply. Both. It would also be interesting to compare them to the GPO 162 and 232 pyramid 'phone circuits. The 162 was used with a No. 1 (wood) or No. 25 (Bakelite) bellset which contained a sidetone induction coil, the same bellsets were used with the No. 150 candlestick. However, the 162 contained a separate 'transformer' which seems to have been an anti-sidetone device of some sort. I'll have to sit down with the N-Diagram and look at the circuit sometime. The 232 which came out a few years later looked almost identical, but was used with a No. 26 bellset, which was similar to the No. 25 but did not contain the induction coil; an ASTIC being mounted in the base of the 232. The capacitor remained in the bellset.
I suspect that the 232 combined with the No. 26 bellset would be quite similar to a D-1 with 102 circuit, other than the induction coil being in the deskset rather than in the subset. Of course, the Bakelite pyramid base gives rather more room to mount components than the D-1 had. Since the 202 circuit kept the induction coil in the subset, and the 302 put everything inside the deskset, I assume that you never had anything, at least not from WE, which used an induction coil in the subset combined with a 'transformer' inside the deskset, as the 162 had.
Quote from: bingster on August 16, 2011, 03:55:51 PM
The subset in the auction appears to be anti-sidetone. Even though it's marked "584," which is a sidetone subset, the induction coil is the anti-sidetone coil. So it may have been altered to make it anti-sidetone at some point in it's life.
It's a nice early one, too, from March, 1930. Surely that must be very early for the bakelite-covered subsets.
Looking closely at the photo of the subset, I see that both the mounting cord and line cord are three conductors. So, my question is this, why would you have a anti-sidetone subset with a phone wired for sidetone?
Thanks!
I noticed the 3 wire phone cord too and I don't know why they would wire it for sidetone. Try it once you get it and see if it works and what it sounds like. A couple of other issues you will need to check out is why there are only 2 wires coming from the condenser. There should be 2 condensers and 4 wires coming from it. Your ringer is not hooked up to a condenser and it should be. Also, your ringer is wired for grounded ringing and that will need to be changed. See what the deal is with the condensers first. Only one of the two wires coming from the condenser is hooked up.
Doug Pav
Wow, sounds like I have my work cut out for me.
So I better understand, is there a diagram of subsets and their parts somewhere here? I'd like to be sure what I think is a condenser is actually a condenser and so on.
Thanks!
The condenser is mounted underneath the bells. You can see the two wires coming from it in the auction pics.
Doug Pav
Okay, let me see if I have this down.
The induction coil (which mine looks to be a 146a) is black with two wood blocks at either end with the L1/L2 and other connectors.
The condensers are the things that looks like lead bars and they are located directly under the gongs attached to the base plate.
The capacitors are the two black objects with 750 printed on them located in the ringer housing.
Am I correct in assuming that this subset is missing the connector block?
Thanks!
BDL, A capacitor and a condenser are one and the same and the words are interchangeable although for the most part when it comes to telephones they call it a condenser. The condenser is the thing that looks like lead bars underneath the gongs. The black objects with "750" stamped on them are 750 ohm electromagnetic ringer coils that make the clapper on your ringer go back & forth. You use all the screws on the 146 induction coil for a terminal block.
Doug Pav
Thanks, Wallphone.
Boy, is this thing pieced together. Parts from the 30s and 50s. The dial was refurbed in 1950 and there is a 149A condenser from 1940. It seems that there are only two connections from the condenser.
In my excitement to get the old paint off, I took the phone apart without testing it first. Probably not the best route, but I'll have plenty of time for that once I get the 4 layers of paint of of this thing.
Hi Everyone. Been reading all the posts and I think I understand this a little better. But I still have a couple of questions. I have a WE phone that has a E1 handset and a D1 oval base. It's a manual phone with no dial. Looks to be very clean and original. At first I though it was a 202 because it had the oval base and 4 wires coming out of the cord that would go to a subset. Looking inside, there's no black wire inside the phone from that cord, so I'm thinking it's a 102. I would like to install a dial, and connect it to a subset, and use it. Installing a dial shouldn't be to bloody hard - just a few screws and wires. I think I can use a 4-H dial or a 5H dial? Will these wire up like a standard 202 but without that missing black wire? Next, I need to select a subset for it. This is a side-tone phone? So it looks like the correct subset box is a 534? But per the above articles I could use a 634 or 684 ok but they would lack the anti-side-tone feature? Are phones now all anti-side-tone in design? Is there anything really terrible about a side tone? I'm not using the phone in a ship engine room but the quiet of my humble little abode. Can you also hook up a 2nd phone to the subset as an extension, such as a candlestick type? What does the anti-side-tone feature really do? Does it just switch off the transmitter from a receiver? By changing the cord on a phone and adding that other back wire, do you suddenly have a 202? How come some of the 634 subsets had different size capacitors? Comments?
Dan,
4H, 5H or 6A will work. You'll also need #4-36 screws. Both a B-1 or D-1 handset mounting can be a 102 or 202: with a 3-conductor cord it's a 102, with a 4-cond. it's a 202.
Perhaps you can find and reterminate the missing black lead by removing some of the outer covering of the mounting cord. If you want to use an anti-sidetone (AST) circuit, you need 4 wires to the subset. There is a way to connect a sidetone set to an AST subset, but then it will be a sidetone circuit.
Sidetone refers to hearing yourself talk through your receiver. The advantages of AST are that (1) there is less room noise picked up and (2) because your own voice isn't as loud in the receiver, you tend to talk louder; thus a stronger transmit level is sent out over the line. AST subsets include 634A, 634BA, 684A, 684BA, 495BP, and the base of a 302 set (including the ringer, induction coil and capacitors).
The advantage of sidetone is that you can connect more than one phone to the same subset. ST subsets include 295A, 334A, 534A. This can be a mixture of candlesticks (20AL, 51AL, etc.) and hand telephone sets such as 102s. You can also use AST telephones (202, 151AL, etc.) with ST subsets by taping up the black lead.
Most if not all 634s are conversions, meaning they were originally manufactured as 534s, most of which had only one capacitor. So either the single capacitor is replaced with a double one, or the old one is left and a second single one is added.
Normally, you can't connect two 202s or other anti-sidetone sets to a 634 or other AST subset. This is because both transmitters would be active even if only one phone is off-hook. There were sets with extra contacts (215, 151R) to disconnect the transmitter when on-hook, but these are seldom found. However, if you don't mind a sidetone circuit, you can use an AST subset acting as sidetone and connect more than one phone to the same subset.
Thanks for the reply. Starting to have a better understanding of the subsets and what they do. Didn't know about multiple phones on one subset or that 634s were modified from 534s. I'll probably start with a 534 and the three wire phone. Looks like I have the option to change it to AST with a different subset box and a different wire to the phone. Guess I have to hear a version to know what I'll like. It be nice to build a small representative collection of the evolution of phones.
Quote from: Dan H on December 03, 2013, 12:18:42 AM
Thanks for the reply. Starting to have a better understanding of the subsets and what they do. Didn't know about multiple phones on one subset or that 634s were modified from 534s.
It is certain that many 534 subsets got converted to 634 sets when the stations were upgraded to anti-sidetone instruments.
However, the catalogs do contain the 634 and its various configurations, so they most certainly were also made new, as independents could order from these catalogs. They would not get refurbished equipment.
As for the model numbers, the 1935 WeCo catalog (#9) explains the method:
"It should be noted that the code numbers of these sets correspond with those of the old sidetone type for various classes of service, except that 100 has been added; i.e., No. 584C Subscriber Set (Sidetone) is No. 684C Subscriber Set (Anti-sidetone)."
Here is an overview table, 4 tables actually on one sheet, of all the station equipment that was used for the various types of service as of 1931.
I compiled this from the pages in BSP C41.101 into one reference sheet. It's a bit dense in terms of information, but still rather useful as a reference.
The tables are arranged by 1) sidetone stations, 2) anti-sidetone stations. Each of these sections is divided into common battery stations, and local battery talking/common battery signaling stations.
Included are the subset models used, and the types of hand telephone sets, or desk stands (candlesticks) for each class of service, including individual lines, and the various party lines configurations.
Alot of very helpful information here - thanks everyone! I haven't even gotten into subsets yet but will be needing one when I finish restoring my WE 202 or (102, not sure now :-\) so this is a good source of info.
Quote from: unbeldi on December 03, 2013, 01:31:58 AM
Quote from: Dan H on December 03, 2013, 12:18:42 AM
Thanks for the reply. Starting to have a better understanding of the subsets and what they do. Didn't know about multiple phones on one subset or that 634s were modified from 534s.
It is certain that many 534 subsets got converted to 634 sets when the stations were upgraded to anti-sidetone instruments.
However, the catalogs do contain the 634 and its various configurations, so they most certainly were also made new, as independents could order from these catalogs. They would not get refurbished equipment.
As for the model numbers, the 1935 WeCo catalog (#9) explains the method:
"It should be noted that the code numbers of these sets correspond with those of the old sidetone type for various classes of service, except that 100 has been added; i.e., No. 584C Subscriber Set (Sidetone) is No. 684C Subscriber Set (Anti-sidetone)."
Catalog #9 (1935) does show some *new* 634s. However, the 634-A is not shown. AFAIK, the only reason for *new* 634s--other than the 634A-- as late as 1935 was that harmonic ringers (41A, 41T, 41U, 41R), relays (85N), and retardation coils (54S) were features never offered in the newer 584/684 format.
Still, I have yet to find a 634-
A, 5302G or 151-AL that was not a conversion. Always looking, though.
Recently I decided that I would like to have another rotary phone and I found Classic Rotary Phones Forum. I'm reading a lot and searching for the phone I would like to own. In this process, I discovered that early phones had subsets. I never knew that. So, I started looking on ebay at phones and subsets. I decided that I like the wooden subsets with the bells mounted outside. So, I bought a 295A subset in a walnut box. This is where I think I went wrong. Now I have to find a phone that matches up with the subset I have.
I've learned that candlestick phones would be the historically correct phone for the 295A subset. But, I can also use a desk set with 102 wiring configuration. Here's where I get a bit confused. I want a round base because I want to set the phone on top of the subset and a round base fits better than the oval base. I also like the E1 handset. You see a lot of these on ebay described as "Western Electric 102 B1 E1" If I've comprehended correctly all I've read, then the 102 and 202 configuration can be found in either the B1 or D1 mountings. Is that correct?
So, what happens if I buy a B1 mounting and discover that it has the 202 configuration? Is connecting this B1/202 to my 295A subset as simple as not using the black lead?
Larry
Quote from: Larry on August 09, 2015, 09:31:39 AM
Recently I decided that I would like to have another rotary phone and I found Classic Rotary Phones Forum. I'm reading a lot and searching for the phone I would like to own. In this process, I discovered that early phones had subsets. I never knew that. So, I started looking on ebay at phones and subsets. I decided that I like the wooden subsets with the bells mounted outside. So, I bought a 295A subset in a walnut box. This is where I think I went wrong. Now I have to find a phone that matches up with the subset I have.
I've learned that candlestick phones would be the historically correct phone for the 295A subset. But, I can also use a desk set with 102 wiring configuration. Here's where I get a bit confused. I want a round base because I want to set the phone on top of the subset and a round base fits better than the oval base. I also like the E1 handset. You see a lot of these on ebay described as "Western Electric 102 B1 E1" If I've comprehended correctly all I've read, then the 102 and 202 configuration can be found in either the B1 or D1 mountings. Is that correct?
So, what happens if I buy a B1 mounting and discover that it has the 202 configuration? Is connecting this B1/202 to my 295A subset as simple as not using the black lead?
Larry
As you are finding out, it does take some research to match the right kind of equipment when constructing old telephone systems. That is probably true in any field, actually. Despite the simplicity of telephony a hundred years ago, there existed still a fairly high degree of sophistication in what was designed for the various types of service arrangements. In a way it was more intricate, as specific services required different types of sets. For example, a local battery telephone could not be operated properly on a common battery telephony line, and today those distinctions are gone. The traditional service types have virtually disappeared and service distinction is implemented by the digital features implemented in the software of the central offices.
so...
Yes, your impression is correct.
A 102 and a 202 desk set is physically almost identical, the only difference being that the 202 has a four-conductor cord to the subset (red, green, yellow, and black wires), while the 102 only has a three-conductor cord (red, green, yellow). The extra black wire of the 202 is attached to an already existing terminal in the desk set, so that there is no physical difference between the two, if you neglect the cords.
In the 1930s, 102 sets, whether they had a B1 or a D1 base, were very frequently converted to anti-sidetone operation, and received a four-conductor cord. That is the only difference you can tell them apart by, when you look at sale ads today, as in the vast majority they do not come with the requisite subscriber set. When telephones got de-installed, either officially or by a home owner, often the cords where cut or the spade tips properly removed from the screws, and over time the instrument got separated from its other half.
In our other discussion thread (http://www.classicrotaryphones.com/forum/index.php?topic=14752.0), I already mentioned that you can simply ignore the black lead when connecting a 202 desk set with a "102-type" subscriber set. Don't cut it off, but wrap it with electrical tape and store the spade where it doesn't interfere, with the ringer for example.
Here is a diagram from my circuit studies that shows the circuit additions in a 202 telephone over the 102 type telephone.
This uses the example of a 534A sidetone subset with a B1 or D1 desk telephone (handset mounting) as converted to a 634A/202 telephone.
You should already recognize the subset portion of the diagram, as the black part of the drawing on the left-hand side is identical in layout to the diagram I showed you for your 295A subset. The 534A subset was a successor to the 295A. They only changed to new components, and a steel case, while the circuit was identical.
On the right-hand side is the desk set. This can be either a B1 or a D1. The switches inside them are only indicated by icons on the traces. A cross (X) indicates a normally open switch, and bar (|) across a trace means that the switch is normally closed. The diagram includes the hookswitch contacts (HS), and the switches on the dial (DP=dial pulse, ON=off-normal).
In red color are shown the extra induction coil winding, an extra condenser, and the extra black wire in the mounting cord that turn a 102-type telephone into a 202-type telephone. You see that the extra mounting cord wire is simply attached to an existing terminal on the dial in the desk set.
This may be a little heavy for starters, but it should not be too hard, and the fun is in figuring it out. There are very few resources available that explain these differences concisely in one place.
RX=receiver
TX=transmitter
PS: I should probably have indicated in the diagram that the point "C" in the 634A was located at position "K" in the 534A, and simply separated as a distinct terminal in the 634A. This required the addition of the new capacitor (C2) whose return lead is now the black mounting cord wire going to the desk set, and back to the same place (L2) after going through the series of switches.
Perhaps it is illustrative and useful to show the 534A subset/102 separately, see second diagram.
Thanks a lot. This is all very helpful and your explanations understandable.
Larry
I wonder if it might be okay to use a three conductor mounting cord with a 634A subset by just tying the B and Y terminals together at the subset.
With the phone off hook, the hook switch and dial pulse contacts effectively tie these terminals together anyway, so for normal speech, it should be no different. With the phone on hook, it's harder to picture just what the induction coil would be doing, but I'd think it just looks like an additional ringer load. I suppose the only question would be whether the coil would be damaged by ringing voltage.
Quote from: luns on October 01, 2015, 06:36:38 PM
I wonder if it might be okay to use a three conductor mounting cord with a 634A subset by just tying the B and Y terminals together at the subset.
With the phone off hook, the hook switch and dial pulse contacts effectively tie these terminals together anyway, so for normal speech, it should be no different. With the phone on hook, it's harder to picture just what the induction coil would be doing, but I'd think it just looks like an additional ringer load. I suppose the only question would be whether the coil would be damaged by ringing voltage.
You noted correctly that during a call (off-hook) the connections would be identical to the four-wire configuration.
The suggested modification is shown in the following diagram, in contrast to the earlier diagrams posted that showed the evolution from the 534A to the 634A/684A subset. As one can see it bypassed the hookswitch in the desk set, and the connection is made already in the subset.
As noted, the problem is the extremely large load not only by the induction coil, but primarily the large 2 µF capacitor in line with the induction coil. This presents probably a 2 to 3 REN additional load on the line.
Normally this is not "ok", but this is in fact exactly what a war-time Bell System Practice advised during time of material and manufacturing restrictions, as outlined in WR-C63.373 Issue 1, dated 1942-09-30. As a consequence, the BSP restricts this use to lines with only one low-impedance ringing bridge on the line.
Of course my diagrams here are for D1 handset mountings which have a different switch configuration than a desk stand (candlestick), but the principle is nevertheless the same.
We had a discussion about this (http://www.classicrotaryphones.com/forum/index.php?topic=8785.0) a couple years ago, or so, when Poplar1 introduced the method. The relevant BSP can be found in his nice collection of wartime BSPs.
I prefer the other diagram that was mentioned in WR-C63.373, since it does not have any limitation on the number of ringing bridges:
http://www.classicrotaryphones.com/forum/index.php?topic=8785.msg117918#msg117918
Quote from: poplar1 on October 01, 2015, 09:22:40 PM
I prefer the other diagram that was mentioned in WR-C63.373, since it does not have any limitation on the number of ringing bridges:
http://www.classicrotaryphones.com/forum/index.php?topic=8785.msg117918#msg117918
Well, the load is not desirable, true, but the 'other' circuit is not an equivalent circuit and does not provide the sidetone compensation. It probably has other transmission deficiencies, and requires more extensive rewiring of the subset.
The 'sidetone reduction' mentioned on the diagram is only marginal, and not true anti-sidetone performance. Basically, it is a funky booster circuit.
My original post in 2013 was about using the Fig. 1 circuit (shown with blue background) for sidetone desk stands such as 51AL) with anti-sidetone subsets (such as 684A), when the only thing available was sidetone phones and AST subsets, and modifying the hookswitch was not practicable.
I also stated that with 102s, the easiest solution is to change the mounting cord from a D3 (3-conductor) to a D4- (4-conductor), thus converting the 102 hand telephone set to a 202. I still maintain that adding a 4th conductor from a B1 or D1 mounting to the 634 or 684A subset is the most logical solution, since it requires no rewiring of the subset and also maintains the intended AST circuit.
B1, and D1 phones are both capable of being either sidetone or anti-sidetone. Just depends on what kind of subset AND CORD you have. For the A1, IF it has a dial with the updated contact set, it also can be either way. Not sure if it has a different contact set though. For candle sticks, I have heard that if it is a 151, it can be either way, but the older ones - 20 AL, 50 AL, etc., that can only be sidetone, even if they are hooked up to an anti-sidetone subset. Never tried though, so that might not be true. Many sidetone subsets were retro-fitted by Ma Bell, so, even with the "5" number - 534, etc., they are now anti-sidetone. 634, 684, 685, etc. were manufactured as anti-sidetone units.
After all these years this info is still enlightening people including a newbe like me. Thanks
No, because the 534 subset has no place to connect the 4th wire to where it would be functional, unless you update that 534 into a 634 subset. The biggest problem, for me, with side-tone is the fact that you hear a lot more background noise from your environment in your receiver. Some people though will speak more softly because of the volume of their voice in the receiver. With anti-side-tone, you don't hear much of that background noise, and your voice is muted by comparison. But side-tone subsets do have an advantage in that you can connect more than one phone to them. With anti-side-tone subsets, you can't, as you won't be able to hang up, just as if the phone in the other room was left off the hook, unless you use phones that are made for that usage. They have an extra set of contacts.
Mike
Mike
Quote from: MMikeJBenN27 on December 19, 2022, 04:15:59 PMBut side-tone subsets do have an advantage in that you can connect more than one phone to them. With anti-side-tone subsets, you can't, as you won't be able to hang up, just as if the phone in the other room was left off the hook, unless you use phones that are made for that usage. They have an extra set of contacts.
Yes, you can hang up, because on both 202s, the Y and BK hookswitch contacts will be open.
The problem is that when either 202 is off-hook, the red and black mounting cord conductors of both 202s, which are not switched, will be live. So you can eavesdrop on the hung up 202 from the off-hook telephone.
You need a 215 (D8 handset mounting) at both locations connected to a single AST subset. The D8 does have additional R and RH contacts which complete the path from R in the subset to the transmitter through the red handset conductor, but only for the phone in use.
I had a very nice, fully functional side tone stick. Sold it. I never got use to hearing the sounds of my hand holding the stick during a conversation. Every slight shift in my hand was picked up by the transmitter and heard in the receiver, quite loudly.