How to Wire 51-501-T with 425A Network, and C3A ringer, & 426A Tube.

[Dan/Panther]

How do you wire The above mentioned Phone.
D/P

[Phonesrfun]

I have that exact phone.  I can help you tonight, but not until after work.

[JorgeAmely]

D/P:

Check the last photos of this album.

http://picasaweb.google.com/Amelyenator/WesternElectric501PhoneWithA426ATube#  ( dead link 1-6-18 )

     Western Electric 501 Phone with a 426A Tube

This album is for a C4A. It will be similar, though. Essentially it is Tip to one side of the ringer, then other side of the ringer to black and red of the tube, and the yellow terminal of the tube to Ring.

[Phonesrfun]

Dan:

Here it is.  I am assuming that the only thing we need to talk about is the ringer and the tube.  Otherwise, of course, there will be more to talk about.

Some of this will depend on whether L1 and L2 are positive or negative as you currently have it hooked up, or will have it hooked up.  First, the wires that don't matter:

This is how mine is wired:

Ringer:

Red = L2
Black = L1
Slate/Red = E
Slate = K

Tube:

Black = E (along with ringer Slate/Red)

Now the part that is polarity sensitive:

If L1 (green) is positive, and L2 (red) is negative:

Hook the red tube wire to A, and the Yellow tube wire to L2.

If L1 (green) is negative, and L2 (red) is positive:

Hook red and yellow the other way around;  Hook the red tube wire to L2, and the Yellow tube wire to A

This note is important.  On my phone, the tube is shot.  It's seen better days.  I need to "help" it along by moving the clapper on the ringer aside slightly to get enough oomph out of it to ring.  So, the success of this is very dependant on tube condition.

If your tube is shot too then you can either try to find another tube, which are available, I believe, or just take the tube out of the circuit and wire it as a straight 500, which requires no modifications other than not using the tube in the circuit.

[Phonesrfun]

Jorge:

As in most phone situations, there are more than one solution to a problem. 

[Dan/Panther]

Does it matter that the C3A ringer only has 2 wires, Red and Black ?
D/P

[Phonesrfun]

Yes.  It simplifies it a bit, but I will need to look at the circuit.  In the meantime, Jorge may have someting too.  He seems to know inctincively how to hook it up, where I need to look at the diagram.

Jorge?  Are you there?

[JorgeAmely]

I am here Bill.

I have played with that tube many times.  And redrawn the circuit in many forms to figure out what the Bell engineers did. Take a quick look at the attached picture.

On the left is how the Bell engineers draw the circuit. This is from one of the BSP books. You can see that they connect one coil in series with the cap and then in series with the second coil (applies to C4A ringer) but they go back to the TIP lead. In the middle, they connect one side of the tube, so essentially they place both coils in parallel, which draws more current from the central office.

On the right I have redrawn the circuit for the case of the C3A (I don't have a BSP with the diagram). In this case there is a single coil, and the tube is connected to ignite when the ringing voltage is present. I have tested the case shown and also where the red lead is connected to the tip directly, but it doesn't make a difference: the ringer rings loud and clear in both cases. Personally, I prefer it as shown because in case of a lightning strike, the tube have more chances of surviving than if connected across the line directly.

Note: Tip needs to be at close to zero volts and RING at a negative battery voltage (usually -48 Vdc) for this to work. The tube is a polarity sensitive device, very similar to a diode.

[Phonesrfun]

Thank you Jorge:

I just got off the phone with Dan.  I had taken your approach and we talked through it over the phone, but although the tube would light for him, it would not ring hooked either way, although Dan said he was going to continue trying.  It may be a case of a tube that has lost its oomph.  When he hooked it up using the built-in cap without the tube, it rang loud and clear.

I have printed your diagram and I am going to keep it handy.

Cheers,

[Phonesrfun]

Jorge:

One other thing about my set-up that was driving me nuts.  My land line isn't really a land line at all.  It is a Vonage Voip line coming through a router.  At rest, there is 48 volts, but when it rings, it drops all DC and only puts the AC ringing current on.  For about an hour, I was baffled as to why I could not get mine to ring through the tube, no matter which way I hooked it up.  It does ring slightly through my Panasonic 616, which uses 24 volts.  It wasn't until I put my volt meter on the Vonage connection and found that it dropped the DC that I realized what was going on.

So, between the lower voltage of 24 volts and the age of the tube, I only get a slight wiggling of the ringer when I ring it through the 616.

Any way, I really appreciate your diagram.

[JorgeAmely]

D/P, Bill:

After spending a few minutes playing with the tube and C3A like ringer (actually a C4B) I want to suggest that you reverse the leads of the ringer. My ringer prefers to be installed with a certain "polarity" and rings very loud in one direction but faintly in the other. This is the ringer I connected once across the phone line without a capacitor, so it seems to have been demagnetized a little. I also had to play with the bias spring to prevent bell twinkle.

Regarding your Vonage line, obviously it was designed by someone that threw the standards book off the window. However, I think they saved some pennies in the ringer circuit design. Phones inside a house don't really need a battery voltage present while ringing. That is probably a remnant of the superimposed ringing days. Only us guys with phones that use tubes need that feature.

Somewhere long time ago I read that the -48 Vdc helps prevent copper migration. That doesn't seem to be true anymore, since the phone company connects the wires to your house at random, regardless of polarity. Donna or any switcher person may have something to add to this.

Attached is a picture of my test setup.

[Phonesrfun]

That test set-up looks like the kind of things I do.   

[Dan/Panther]

Looks like my stuff also, just a lot neater 

D/P

[Jim Stettler]

I think the -48 was for  protection of the lead sheath of the cable. I read an article that stated (- )would thicken the sheath whereas (+) would thin it.
Realistically this takes a really long time.

Nowadays utilities use "Cathodic protection" on underground lines . This includes all undground pipes and cables.

Jim

[Dan/Panther]

I've decided to wait until I have all of the phone complete before I attempt to get the wiring worked out.
Progress is proceeding nicely. Here are a few photos.
If you will notice in the fourth photo, the Line Contact Switch levers and mount frame are Aluminum, what years were they made out of aluminum ?  Actually it appears to be Aircraft Grade aluminum, which is much stiffer and stronger. Doesn't bend near as easily as beer can grade aluminum. I thought the Pre-Production was when they decided to go to Cadmium plated steel ?
D/P