Vacuum Tube technology.

[Dan/Panther]

I was hooking up my WE500 phone, and I removed the dial to hook up the handset wiring. Tucked under the dial, and out of sight, low and behold I find a 7 pin miniature vacuum tube.
Why wasn't I told about this tube....
My question, does this tube ever go bad, what is it's number, and
what does do.
If it goes bad it appears you have to replace the entire little module, if that ever happens, has anyone ever just installed a 7 pin tube socket.

Dan/Panther

[BDM]

Why weren't you told about this tube? Because folks in Cali aren't privy to this info.......But now that the secret is out, have a look at this article.
http://mysite.verizon.net/paul-f/we500typ.htm

After you're done reading, you can either leave it, throw it out, or place it in your trophy stand. Well, unless you plan on using a party line?

[Dan/Panther]

We must be the Red Headed step child of collector states, it's the same in radios, nothing ever makes it West of the Mississippi. All of the good items seem to be back east or midwest. Now they're depriving us of vital information.
What next, Will Mickey mouse move to florida ?

Da/Panther

[Dennis Markham]

I guess I should have read this post before reading the other about the dial tone problem.

Check out this great web album created by California telephone collector, Jorge Amely.  Jorge did some work with the 426A vacuum tube that appears in some model 500 phones.  Its purpose was party line related.  Check out this album.  It may answer your questions about its purpose and how it works.  Jorge removed the black paint that covers the tube so that he could photograph the ignition of the gas inside while charged.

http://picasaweb.google.com/Amelyenator/WesternElectric501PhoneWithA426ATube#

The web album instructs one on how to properly connect the wires as well.

[Dan/Panther]

Dennis;
I read what Jorge wrote, and it really doesn't explain how, or why it's there. Did I miss something.
If it indeed works with or for a Party line, I'm familiar with party lines, will the light either go off, or come on, if both parties are on line at the same time, and if so, could it be used to indicate when another phone on the same line is picked up, like as if someone is listening in?
Now that has potential.

Dan/Panther

[Bill]

Dan -

I don't think so. It appears that it has something to do with the ringer. Without a diagram of the innards of the tube or its connections, I can't be sure. But if we are talking party lines, where I think the ringer voltage would be supplied between L1 and ground for one party, and L2 and ground for the other party, perhaps it has to do with keeping the ring voltages for the two parties separate. I understand that quite often, if the ring signal was sent to one party, the other party's ringer would "ting" a bit. Cross-coupling of some sort. Perhaps this tube prevented that.

There are three wires coming from the tube socket. We need to know what those three wires represented within the tube. My guess is an anode, a cathode, and a trigger. Anyopne? Anyone?

Bill

[Dennis Markham]

Good afternoon group,

I am not a technical guy so keep that in mind.  I was under the impression--from what information that I've been "handed down" that the tube was involved with party ling ringing.  Rather than using frequency ringers, like some phone companies did, I think the tubes were intended as Bill described.  They were not intended as an external indicator giving a visual indication of when an incoming call was intended for the user.  They were intended to isolate ringing to a particular phone.  I'm not an electrical guy so I don't know how that was accomplished.  I guess Jorge's experiment was to show that the tubes still work today and would work if the phone system were still configured as it was at the time.  I know that it can be wired so that the phone will work on today's system--obviously Jorge has shown us that.   I believe this is the way the wires should be connected if one wanted to keep the tube active inside your phone, even though it serves no purpose.

Tube (BK) to network (K)

Tube (Y) to network (L2)

Tube (R) to network (G)

Just yesterday I picked up another flea market model 500 from 1952 with a 426A tube inside.  I have also picked up a couple of 302's with a tube, although it is a bit larger.

[Mark Stevens]

I have also picked up a couple of 302's with a tube, although it is a bit larger.

You're pulling our legs, aren't you... 302's with tubes?! 

[Dennis Markham]

No....no leg pulling.  I may have a photo somewhere BEFORE I removed the tube.  More info to follow reference the vacuum tubes.

[Dennis Markham]

Ok gang....here are a couple photos of a vacuum tube that was put in Model 302 telephones.  A bit larger than the 426A tube found in the Model 500's.  I couldn't locate the original but have an image that was re-sized for e-mail.  The accompanying photos I just took this afternoon.  The cardboard protective sleeve appears to be original to the phone.  Note the installers pencil signature on the sleeve.  Also there are some hand written initials on the mounting bracket.

Dennis

[Mark Stevens]

I'm amazed...I want one of those! 

[Dennis Markham]

I asked Jorge Amely if he would provide an explanation in his words of the function of the 426A and 372A tubes.  He was kind enough to make the following explanation:

The benefit that the 426A tube provided was in the ability of the tube to isolate the line from ground when the ringer was not used. Back then, telephone lines were referenced to ground, that's why there was a yellow wire that needed to be connected to ground. Instead of ringing from L1 to L2 (this is the way ringers are installed today), ringers back then were connected between either L1 and L2 and ground. The problem that arrangement caused is that when you have a bunch of ringers connected to L1 or L2 to ground, the line is loaded with many ringers in parallel.

Ringers are isolated from ground by the series capacitor, but many of these capacitors in parallel affect the ability of the line to carry speech without distortion.

To prevent that, WE and a few others began to use the tube in series with the ringer to ground. The benefit is that the lines are isolated from ground, but when the ringer voltage shows on the line, the gas in the tube ionizes (similar to ignition, but when the voltage is removed the gas can be reused, unlike when you ignite oxygen in the presence of hydrogen: it turns into water, but it is difficult to go back to the molecular oxygen only state) and provides a very low impedance path to ground thus allowing the ringer to ring. When the ringing voltage goes away, the tube is essentially an open circuit and isolates the line and ringer from ground helping to prevent a line unbalance.

When party lines went away, all that complexity went out the window also. However, you can still wire your phone to use the tube if it is available inside the phone.

Everybody got that now?? There will be a quiz.  

[Bill]

Ok gang....here are a couple photos of a vacuum tube that was put in Model 302 telephones.

And the photo clearly shows the "biased ringer" that I mentioned over in the General Discussion forum. Nice when that happens.

Bill