What's good Ohms#? One Rotary will Dial Out; Other Won't; dialtone interference

[oldphonefan]

Would appreciate any help. Wondering what the proper resistance range for an old rotary phone should be, when measured with a simple meter across the red and green wires going into the phone (of course when the phone is NOT connected to the line).  [Ignore the bell; assume I have that disconnected.]  I think this might be why a 60's era Bell rotary phone will dial out (I'm on Verizon Fios digital voice) but my AE40 won't.  I think my problem might be the resistance of the AE40 being not right, and I am guessing I need to add a resistor in line, but wondering if this can cause inability to dial out, and also what resistance level I should shoot for; is 200 ohms about right?  I've noticed that when a "new" typical phone and my AE40 are both off the hook, my new standard phone touchtones can't even be heard in the AE40, and in fact it sounds like the dialtones in both the new phone and the old AE40 are interfering with each other (almost like stepping on each other) when both are off the hook just listening to a dial tone.  Yes, my AE40 dial will break the dialtone when I try to dial out, but it isn't dialing any correct phone numbers.  My second choice is maybe the dial speed of the AE40, but it seems about right so I am guessing that due to the interference between the AE40 and any other phone that's on the same line when both are off the hook it has something to do with the AE40 drawing not the right amount of current which I am guessing has to do with improper resistance.  I can check it with my meter and presumably can add a resistor in series if I need to increase the resistance, or in parallel to decrease it, but i'm not even sure what level I should be shooting for.  Any thoughts?  Thanks all!

[unbeldi]

First of all why do you think a resistor would improve things?

During dialing the phone should draw the maximum amount of current that the line can possibly provide.
Reducing the current can make it only worse.
It is a very common design in classical phones, such as the Western Electric 302, and the AE40, to short-circuit the line entirely  when winding up the rotary dial. Upon release of the wheel, the signal alternates between low voltage (0V, shorted) and high voltage (CO battery level).

So, somehow the AE40 is producing out-of-specs supervision trigger levels for the FiOS terminal device.

Measure the resistance of the AE40 when pulling the dial (0 against finger stop) and compare that to the other phone.

Since the AE40 does indeed break the dial tone, it stands to reason this is not the problem.  The cause may be dial speed, but it is not easy to tell by looking at the finger wheel. Putting a stroboscope wheel onto the finger wheel is better, but a lot of work since you have to make one.  Try accelerating the return of the finger wheel by applying some positive pressure in the direction of rotation during the return trip, often this helps with proper dialing when the dial speed is marginal.

There is no such thing as dial tones interfering. On both phones you are hearing the same dial tone.

[dsk]

Hi and welcome to the forum.

It is not easy to just measure the ohms, because the value may not be stable, depending on voltage/current, angle of handset etc.

If it works to answer a call it should be OK.

Putting a resistor across the transmitter element could help on both this and statics. (200-330 ohms?)

Putting 2 telephones off hook at the same time will prevent dialing!

The best indication might be to measure dc current when off hook.

If 2 telephones on the same line are offhook they may cause trouble for each other.

The speed of the dial could be analyzed by recording a few zero's on the computer, and and looking at that in audacity.

dsk

[oldphonefan]

Thanks all.
Regarding the resistance (ohms), I measured the AE40 (off-hook but of course not connected to the line); it was about 100 ohms, whereas my other rotaries that didn't mess up my phone line were all in the 500 - 800 ohm range.  So I added a 400 ohm resister (in series) on the line in to the phone, which brought it up to 500 ohms, so it works great now.  At 100 ohms it was messing up the line and other extensions on the same line, but at 500 it's perfect.  Just posting this so others would know.

I was able to speed up the dial a bit by adjusting the governor bars (per another old post in this forum) and that allowed it to dial out fine now.

[Phonesrfun]

There must be something wrong internally that requires you to insert a resistor.  An AE 40 normally is "good to go" and does not need any adaptation.  Troubleshooting something like that might take some time, so if the resistor works, then what the heck.

[Kenton K]

Just curious, is there any dc voltage across the receiver?

KK

[oldphonefan]

First of all, Happy Thanksgiving to all of you!  KK, do you mean DC voltage (measured across the incoming pair of line wires) when the phone is off-hook, or do you mean measured to the handset?  I'd have to play with this to figure this out.