WE 51AL Candlestick phone - just some questions

[Mark55]

Hi everyone -

I recently obtained a WE 51AL candlestick phone which is connected to a WE 684A subset-ringer box. This phone is in great shape, but since this is a new hobby for me, I do have some questions about it.

- When I use the original 337 transmitter, the voice level starts out strong, but after a minute or so of talking it gets pretty weak. It might need some calibration, but I don't know how to do that. Any suggestions? Or is that normal for a transmitter that old?

- If I replace the 337 with a Bulldog transmitter, the sound quality of the voice is much improved and is much stronger, though some people say they still have difficulty hearing me on it. Others say it sounds just fine. Is that normal?

- How do I know if the 684A subset-ringer box is working correctly through and through? It does ring strongly. What is an "induction coil"? The box is date stamped III 36. Do they usually last 74+ years?  The dial tone on the phone is pretty good.

- I'd like to be able to use the original 337 transmitter in place of the Bulldog, to keep this phone as original as possible, but again, it may need some calibration. I don't know how to do that - this is all very new to me. Any suggestions would be greatly appreciated.

thanks much!

[Jester]

Welcome, Mark.
It is common for the carbon granules in the 337 transmitter to clump together, causing the weak signal you describe.  This is the main reason the 635A bulldog became a standard retrofit on 'sticks like your 51AL--it is much more efficient & reliable, even during long periods of use.  As you said, though, the bulldog can still give a weak transmission, but that has more to do with the design of the phone & how the transmitter is mounted.  Phones from this time period were meant for five to ten minute long conversations, so using one can be uncomfortable in terms of both holding & speaking into/listening to a conversation.  The basic job of the induction coil is to drop the power provided by the phone line to the smaller amounts needed by some of the components.  Basic power supply is @24VDC, but many internal components are designed for 6-8VDC.  Hope this helps.                                           

[Phonesrfun]

Hi Mark, and welcome to the forum.

Lots of questions.... Let's see if I can answer some of them.

The 337 transmitter is a later model of what has been called the solid back transmitter, which was developed around the turn of the century and used up through much of the 1930's.  At the time, it was state of the art.  Now, even the best of them would be judged inferior as to sound quality.  Mostly very tinny sounding and susceptible to other problems.  The problem you describe is probably one of the carbon granuals packing and becoming fused together.  The adjustment of these is not one that can easily be done, but one solution is to rap them on a table to dislodge the packing and fusing effect, but is not really a permanent fix.  If you are going to use the candlestick as a "daily driver" the bulldog transmitter that uses an F1 transmitter elemement is a better choice, but of course, the bulldog does not look as cool as the original 337.  The F1, and any carbon transmitter for that matter are susceptible to packing, but the F1 is a better transmitter, both in its construction and its frequency response.

As to the fact that some will say that the bulldog is good and some will say that it is bad, that, I would say is a normal response.  Some people are more forgiving than others as to sound quality.  Any carbon transmitter will sound a little rougher around the edges than more modern transmitters found in electronic telephones these days.  The F1 is generally a good transmitter and the good quality can be expected to last even to these days, but again, they will never be as good as a modern electret tranmitter found in modern electronic phones.  Even the solid back 337 sounded good to people in the 1930's, but it is just a matter of what people get used to hearing and what they expect, and what their threshhold of acceptace is.

The best bet is for you to have someone call you on your 51AL and have you listen and judge for yourself.  Usually part of the fun of collecting phones is to use these and experience the way they sounded way back when.

On the subset, there really is not much to go wrong, and almost never go bad.  The most frequent failure in them is the capacitor, but it is usually a go/no-go situation.  If it is working, then it is probably working just fine.

The induction coil is the heart of a legacy phone.  These were found in every phone from the turn of the century, and even for the 500's that are being produced today, the induction coil is still used.  The induction coil functions as a way to match the impedance of the line to the telephone receiver and transmitter, and provides some amplification as well.  These things just don't fail very often.  

In older telephones, the induction coil, the capacitors and the ringer were just too large to fit all in one unit with the rest of the phone, and therefore there was the desk stand that consisted of the transmitter, receiver, dial and switchhook, and there was the subset, which was the rest of the telephone.  Once the 302 came on the scene in 1938, the technology was such that the whole phone could be self contained, but the 302 used the same electronic technology as earlier antisidetone candlesticks.

Hope this helps.

[Mark55]

Thanks very much, Stephen and Bill. Both of you helped a lot.

I had read a little about the "carbonization" on the old 337 type transmitters, but just wasn't sure if there was anything that could be done about it. I may put the 337 back in (after rapping it on the table!) and see what happens. It does look a lot cooler than the bulldog, plus its original.  It did have that tinny sound to it, but like you said, it was state of the art back then, and that's the fun of collecting and using these old phones.

I have made quite a few calls on this phone using the bulldog F1, and it sounds fine to me, both in talking with people and leaving test messages for myself on the cell phone voice mail. People probably just aren't used to hearing an older style transmitter like that.


So thanks again for all your help, and the info on the subset. If I can think of any more questions, sure will post them. You folks are great - a goldmine of information!

Mark

[dencins]

- When I use the original 337 transmitter, the voice level starts out strong, but after a minute or so of talking it gets pretty weak. It might need some calibration, but I don't know how to do that. Any suggestions? Or is that normal for a transmitter that old?

If the voice level starts strong I do not believe it is a calibration issue.  It also does not sound like carbon clumping.  Calibration is done by adjusting the carbon module pressure against the diaphragm and carbon clumping (carbon granules adhere to each other) would give weak volume all the time.

Solid back transmitter are very directional.  You have to speak directly into the mouth piece to get the volume and tone .  With a candlestick, the tendency is to drfit away from the mouth piece as the conversation progresses.  Probably a reason conversations were shorter back then.

Dennis

[Mark55]

- When I use the original 337 transmitter, the voice level starts out strong, but after a minute or so of talking it gets pretty weak. It might need some calibration, but I don't know how to do that. Any suggestions? Or is that normal for a transmitter that old?

If the voice level starts strong I do not believe it is a calibration issue.  It also does not sound like carbon clumping.  Calibration is done by adjusting the carbon module pressure against the diaphragm and carbon clumping (carbon granules adhere to each other) would give weak volume all the time.

Solid back transmitter are very directional.  You have to speak directly into the mouth piece to get the volume and tone .  With a candlestick, the tendency is to drfit away from the mouth piece as the conversation progresses.  Probably a reason conversations were shorter back then.

Dennis

Thanks, Dennis.  I have messed with a little - took it apart and tried to "fix it." And I probably messed it up even worse! How does one adjust the pressure of the modules, then?

[Phonesrfun]

I don't think you will find any instructions anywhere officially, because they were pretty much factory set and not something that a field service person, even in the day, would even try to attempt.  I have played around with them and fouled a few up myself. 

Dennis, do you have any suggestions?

[Mark55]

This may be a little out in left field, but I'm assuming that the distance - even incredibly small - from the module tip to the diaphragm would be a factor. I have some old gap gauges that were meant for cars, going down to something like .002" at the smallest. It may be impossible to give an exact distance, but if someone could give a close estimate, I could monkey around with it and try it. And then go from there. Its not imperative, but it would be nice to get that old 337 fully functional. Sure am learning a lot here - and thanks for all the help.

[Phonesrfun]

There should be no gap.  The diaphragm must always be in contact with the carbon button, otherwise there would be an immense amount of distoriton.  In fact, with the older solid back transmitters, like the 229, for instance, the diaphragm was physically connected to the button with a screw. 

As Dennis has said, these transmitters were highly position-sensitive.  They were only designed to be used in an upright position with the mouthpiece facing the user's mouth.

I think as far as setting it for optimal sound, there is a set screw in the back of the bridge piece that can be loosened and the pressure of the button against the diaphragm can be set using trial and error.

I cannot remember if the carbon button has a threaded adjustment to adjust how compact or loose the granuals are within the button, but I don't think that was an option.  Perhaps Dennis can chime in with some more information.  I am at work at the moment, and so I don't have access to anything to look at.

Good luck!

[Mark55]

Bill - yes, there is a set screw in the back. There is some kind of threaded thing on the brass assembly there -  is that what you were referring to? I haven't messed with that because I don't know what it does. I'll try to upload a pic and you could see what I'm referring to. 

[dencins]

Bill - yes, there is a set screw in the back. There is some kind of threaded thing on the brass assembly there -  is that what you were referring to? I haven't messed with that because I don't know what it does. I'll try to upload a pic and you could see what I'm referring to. 

The only adjust is the module pressure on the diaphragm.  The is adjusted by:

1.  Loosen the set screw on the top of the bridge
2.  The post will then be able to move up and down
3.  I use leads to attach the transmitter to my laptop then talk into the transmitter and play the sound through the laptop while adjusting the height of the post.
4.  When I hit the sweetspot  (place where it sounds best) I tighten the set screw.

There is no adjustment to the carbon.  If you loosen the collar it will break the mica seal that holds the carbon granules in the modules.  The amount of carbon is measured in grains so trying to replace the carbon is not for the faint at heart.

Dennis

[Mark55]

Thanks, Dennis. How do you attach it to your computer using leads though? Like from what on the 337 to exactly what and where on the computer? And what audio program should I use?

[dencins]

Thanks, Dennis. How do you attach it to your computer using leads though? Like from what on the 337 to exactly what and where on the computer? And what audio program should I use?

I use Microsoft Sound Recorder since it came with Windows XP on the laptop but you can use any audio program you have available.  I speak into the transmiter and record the voice then play it back.  If I sounds good I am done otherwise I adjust and try again.  In most cases the sweetspot is very close to the force exerted by the spring - sometimes it needs a little more and sometimes a little less.

I plug the leads into the MIC jack on the laptop.  The other ends of the leads are attached to the same screws used to connect the transmitter to the telephone.  For the 2XX type transmitter with the carbon block for the transmitter connection, I soldered a cut off nail to one of the leads to insert into the carbon block connector.

I used an old headset to make the leads.  I just cut off the earphones.

Dennis

[dencins]

Thanks, Dennis. How do you attach it to your computer using leads though? Like from what on the 337 to exactly what and where on the computer? And what audio program should I use?

I use Microsoft Sound Recorder since it came with Windows XP on the laptop but you can use any audio program you have available.  I speak into the transmiter and record the voice then play it back.  If I sounds good I am done otherwise I adjust and try again.  In most cases the sweetspot is very close to the force exerted by the spring - sometimes it needs a little more and sometimes a little less.

I plug the leads into the MIC jack on the laptop.  The other ends of the leads are attached to the same screws used to connect the transmitter to the telephone.  For the 2XX type transmitter with the carbon block for the transmitter connection, I soldered a cut off nail to one of the leads to insert into the carbon block connector.

I used an old headset to make the leads.  I just cut off the earphones.

Dennis

I marked up your picture to show the screws.

Dennis

[Mark55]

Ok, thanks Dennis. I'll give that a try. I'll have to get some material, but will try it and let you know what happens.

Mark