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Old 14th Feb 2018, 11:03 am   #21
ct92404
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Default Re: Kellogg wall phones - need help

I couldn't find any helpful information on the induction coil. It just says "No 19" which I'm guessing is just a part number or something for ordering a replacement from the company.

Do you have any idea of what time period these phones might be from? I'm really curious about how old they are.

Steve, I just saw your post. Thank you for the info, and I'm definitely going to look for that book you suggested!
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Old 14th Feb 2018, 11:30 am   #22
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Default Re: Kellogg wall phones - need help

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Originally Posted by Dave Moll View Post

Incidentally, the switch of the GPO magneto 26N/26P works to make the magneto electrically invisible when at rest, but with the handle off-normal (I don't think it needs to be turning) disconnects the local end and connects itself across the line to send its ringing current.
As opposed to the Soviet TAI-43 field telephone, which has the magneto shunted until the handle is turned. Cranking the handle shorts the local bell and speech cct and puts the ringing supply on line via a key. If the key is pressed, the short is opened and the local bell rings as well, as long as there is a load at the other end (or a locally-applied strap): a handy test to see if the generator works!

It means, though, that if there is muck on the magneto switch contact the call will be routed via the magneto winding impedance, and if inadvertently cranked during a call, the speech path will be shorted out.

I can't see any advantage to the way the Kellogg magneto is wired (according to the drawing). Perhaps it's just economy of wiring with the same terminal arrangement being provided for different telephones? Or maybe it's been drawn incorrectly (as suggested)?
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Old 14th Feb 2018, 11:31 am   #23
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Default Re: Kellogg wall phones - need help

The induction coil is an Anti sidetone coil, those were introduced pretty late on LB (local battery) telephones, but it is a wood telephone, and it has cotton cowered cords so this makes me guessing around WWii. Here in Norway those coils where introduced as late as 1934. (The same year wooden telephones became history) Cotton cords remained in use up to 1953. Even when USA was early on telephone development, the kept on making wooden telephones longer, so my guess is approx WWii. Your phone are not mentioned in the book mentioned, still it is a good book!

dsk

PS
Russell W. B. has a good point about how to do it, but this was not common by North Americans, nor Ericsson. The German phones used it: The WWii field telephone FF-33 used the same circuit, with a test button. Norwegian phones used it but had still a hook-switch. (schematics earlier in this thread) By my opinion The German FF-33 is the best (most reliable)hand-cranked field telephone ever made, closely followed by the US EE-8.
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Old 14th Feb 2018, 11:45 am   #24
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Default Re: Kellogg wall phones - need help

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Originally Posted by dagskarlsen View Post
The German phones used it: The WWii field telephone FF-33 used the same circuit, with a test button
As I understand it, the Soviet TAI-43 was a 'rip-off' of a captured German FF-33 and is a pretty robust design. I think the German instruments used different speech battery voltages, though.

Although a WWII design, my TAI-43s date from 1959.
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Old 14th Feb 2018, 6:21 pm   #25
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Default Re: Kellogg wall phones - need help

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Originally Posted by ct92404 View Post
Dags, thank you for drawing that schematic! That definitely helps!

I had another quick question - in general, how reliable are the capacitors in these old telephones? Should I replace it? When I've worked on antique radios, I usually had to replace several capacitors, especially electrolytic filtering ("smoothing") caps and wax ones. If I do replace the capacitor, I'll leave it installed for historical purposes and just clip the wires and put a new cap across them. But should I bother with that, or do you think the original capacitor might still work?

Oh, and I just tested the ringer. I hooked up one telephone to the other...when I cranked the first one, the bell rang on them both! So at least I'm getting there!
The set is provided with an anti sidetone network, and a 6 bar magneto.

This phone is used on long, or populated lines. The network is a bridge
which has an arm that is the line.

Whatever the specifics of the original capacitor, the phone company
would have matched the capacitor. Pacing a new capacitor, with a radically
different D factor, will alter the sidetone.
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Old 14th Feb 2018, 6:37 pm   #26
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Default Re: Kellogg wall phones - need help

I have been looking at the schematics, and the pictures, and it looks like it may have been refurbed at one time, so the box with ringer and inductor may be older then the rest. It looks like it has been an older induction coil mounted on the back wall over the inductor, the connection plate on the left wall looks more modern. I asked a friend about the schematics, and he suggested this could be a Leich telephone, and not Kellogg.
Regarding the capacitor so is that an option in the schematics so it would be fine with, and without.

This does not make things simple, but absolutely interesting.

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Old 14th Feb 2018, 7:43 pm   #27
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Default Re: Kellogg wall phones - need help

Based on Leich telephone photos on Ebay, I have tuned the chematics, I am almost 100% sure that this is right, and the error in the original diagram never was seen.

dsk
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Old 14th Feb 2018, 9:09 pm   #28
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Default Re: Kellogg wall phones - need help

Yes connection of the magneto coil to the centre contact makes much more sense than to the normally-closed one that's opened on operation. Well done for working out the error in the drawing.

So one end of the coil (white lead) goes to L2 and one end of the ringer while the other is disconnected at rest but connected (green) to the other end of the ringer and L1, placing it across both the ringer and the line, causing both ringers (local and remote) to operate. The ringer is permanently connected across the line.
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Old 15th Feb 2018, 3:49 am   #29
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Default Re: Kellogg wall phones - need help

Thank you, Dags! Good work! That diagram makes a lot more sense. It's funny that the company made a mistake in the diagram and apparently no one caught it.

I measured the resistance across the magneto terminals with the crank at rest and got about 1600 ohms, which matches up with the bell ringer. With the magneto handle turned (but not cranked) to move the contacts, I got about 147 ohms, which means the armature winding itself. It's making more sense now. When the magneto is not being cranked, it's removed from the circuit, probably just so that current from an incoming ring doesn't go through it. It's much easier to see now with the correct diagram. When you turn the magneto, the contacts are moved, putting the local bell and the phone line in a parallel circuit across the magneto.

Dave, it's good to know we weren't both going crazy!
This whole time, there was just a mistake in the original diagram!

The only thing that still kind of confuses me is what was the purpose for the normally closed contacts? It seems like the way this telephone is wired, they don't really do anything. All you would need is a simple mechanism to disconnect the magneto from the rest of the circuit when it's not in use. You only need one set of contacts. Why have two? I also don't understand what the extra screw terminal was for. Maybe that magneto was used for several different telephone models that wired the magneto differently? It's weird.
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Old 15th Feb 2018, 7:54 am   #30
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Default Re: Kellogg wall phones - need help

Try this out, move from red dot to yellow, and mount yellow strap. What happens?

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Old 15th Feb 2018, 8:47 am   #31
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Default Re: Kellogg wall phones - need help

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Originally Posted by ct92404 View Post
When the magneto is not being cranked, it's removed from the circuit, probably just so that current from an incoming ring doesn't go through it.
That is indeed the reason.

Quote:
Originally Posted by ct92404 View Post
The only thing that still kind of confuses me is what was the purpose for the normally closed contacts? It seems like the way this telephone is wired, they don't really do anything.
The magneto would probably be a general purpose one, and that contact may be used in other circuits. For instance, in the GPO magnetos I mentioned in an earlier post, the NC contact allows a through path between the local 'phone and the line, which is broken while the magneto is being cranked so that the magneto output is not fed back into the local 'phone.

It looks as though it would be possible to wire your 'phone so that this contact would disconnect the local ringer while the magneto is cranked if you didn't want it ringing while you crank.
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Old 15th Feb 2018, 9:25 am   #32
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Default Re: Kellogg wall phones - need help

Quote:
Originally Posted by ct92404 View Post
I couldn't find any helpful information on the induction coil. It just says "No 19" which I'm guessing is just a part number or something for ordering a replacement from the company.

Do you have any idea of what time period these phones might be from? I'm really curious about how old they are.

Steve, I just saw your post. Thank you for the info, and I'm definitely going to look for that book you suggested!
As assist, therein will be found.
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Old 15th Feb 2018, 9:48 am   #33
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Default Re: Kellogg wall phones - need help

I am pretty good on making konfusions, but here we have to clarify some points.

1) I would rather say this is a Leich than a Kellogg

2) The pretty well designed triad circuit is a CB circuit, this is a LB circuit. LB ciruits did usually not use a booster circuit, except for where it was a modified CB circuit, and the transmitter was powered by a local battery, and a choke. (Typical US Field telephone TA 312 TP )

3) The extra set of contacts on the inductor was for use when silent ringing was used.

4) Local battery, anti sidetone circuits was usually made as a bridge, pretty equal to the triad mentioned over, but with no capacitors as anything else the a DC or ring frequency blocking/breaking. much more to read here: http://www.samhallas.co.uk/repositor...i-sidetone.pdf

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Old 15th Feb 2018, 10:15 am   #34
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Default Re: Kellogg wall phones - need help

Quote:
Originally Posted by Dave Moll View Post

The magneto would probably be a general purpose one, and that contact may be used in other circuits. For instance, in the GPO magnetos I mentioned in an earlier post...
The 'Magneto 26A' used since about 1940 was not only used in LB telephone circuits, but was used in the Beethoven shot-firing exploder where the 'close-on-turn' contact was configured to good effect. I agree that the magneto in the OP telephone would have been manufactured with the contacts configured for 'economies of scale'. This was an established practice with GPO telephones in any case: interchangeability of parts on economy grounds.

Quote:
Originally Posted by Dave Moll View Post
It looks as though it would be possible to wire your 'phone so that this contact would disconnect the local ringer while the magneto is cranked if you didn't want it ringing while you crank.
A glance through H. G. White's 'Telephone Erection and Maintenance' of the 1920s reveals that 'Silent ringing' was an option for this type of telephone, and that local bells ringing was not unusual, although the telephone described in the book had the bells in series with the magneto and was restricted to short lines of less than ten miles. No mention of bells permanently shunted across the line (like on the TAI-43).
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Old 16th Feb 2018, 1:59 am   #35
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Default Re: Kellogg wall phones - need help

Success!
I connected the telephones together and I was able to transmit between them! I'm powering them with one C battery each.

Surprisingly, the phone with the older handset seems to have a much stronger transmitter. I had to coax the microphone and fiddle with it for a while, but once I brought it back to life, it sounded loud and clear on the other phone.

The wiring on the phone with the modified handset is pretty bad. It works now, but I think I'm going to have to rewire it at some point for a permanent fix. The original wiring is getting brittle and is kind of messy. 3 wires had broken and I had to patch them back together with solder. Actually, I might have to rewire both telephones at some point. The way they ran the wiring harness over the edge of the cabinet to the door puts strain on the wires and I think eventually they're all going to start breaking, especially since they're solid conductor and kink easily. I don't really want to replace the original wiring, but I might have to eventually. Maybe if I can find some cloth covered stranded wire that looks authentic.

But at least for now, the telephones seem to be working pretty good and it's fun playing around with them.
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Old 16th Feb 2018, 9:05 am   #36
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Default Re: Kellogg wall phones - need help

Congratulations. It's good to know that you are now up and running with your 'phones.

The fact that the newer handset has a weaker transmitter may indicate that it is a poor match for your 'phone, being intended for a more modern 'phone, rather than having a fault in it. It may be worth looking out for a handset of the correct era. It may also be worth experimenting with an increase in battery voltage on that 'phone - though if it's an electret, I wouldn't expect it to work at all at 1V.

Incidentally, it sounds as though you may have had to "wake up" the carbon granules in the older transmitter. They can settle and stick together after extened periods out of use, so agitating them gets them working again.
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Old 16th Feb 2018, 5:17 pm   #37
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Default Re: Kellogg wall phones - need help

Congratulations, it has been interesting to be a part of this, and I have learned something this time too. As Dave says a handset from the right era will be better, until then you could increase the voltage to 3 or maybe 4.5 V. Use an ampere-meter and monitor the current to be 20-35 milli-amps, then you will be close to the right voltage for that setup. Use the smallest voltage that pulls the current over 20 milli-amps.
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Old 17th Feb 2018, 2:45 am   #38
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Default Re: Kellogg wall phones - need help

Thank you for the suggestions.

It looks like I might have spoken too soon though. I think the microphone on the older handset finally gave up. It's completely dead now, I'm not hearing anything on the other telephone when I try to talk through it. The earpiece is still working okay, but nothing from the microphone. I tried tapping and shaking it and still nothing. I'm not sure what else to, so I guess I'll just have to try to replace it.

I found a few websites that sell parts for restoring antique telephones, and I saw a Kellogg microphone that looks the same as the one I have. (I hope they test them though, I don't want to end up with another bad one).

http://www.oldphoneworks.com/kellogg...r-element.html

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Old 17th Feb 2018, 8:48 am   #39
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Default Re: Kellogg wall phones - need help

OK Transmitters do usually not die quickly, so it may be the cord, or the springs.
A way to test the transmitter element is to put up the transmitter, a working receiver and a battery of 3-9 V in series. (With voltages of more than 4.5 V be careful to not test more than 30 seconds at the time to reduce the risk of getting a current over 50 milli-amps, that may fry the transmitter!)

To test the wire you could start with removing the transmitter, and measure voltage over the springs in handset, it should be equal to the battery voltage. shorting and removing the short should be loud clicks in the receiver.
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Old 17th Feb 2018, 8:48 am   #40
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Default Re: Kellogg wall phones - need help

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I hope they test them though, I don't want to end up with another bad one.
It appears they offer a 90-day warranty.
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