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Old 15th May 2024, 12:12 pm   #1
Sir_Lunchalot
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Default Advice On Type L Field Phone

G’day everyone!

This is my first time posting here, so I hope that I am doing so in the correct section.

I have recently bought two Type L field telephones out of personal interest. I would have got Type F’s, but it seems that they are few and far between in Australia.

Anyway, I have received one in the mail already. When I bought it, I knew that it had seen a lot of use, and had been modified with a rotary dial for civilian use (perhaps by a technician?), but now that I have looked at it in person I notice something strange about it. Namely, that it is missing the characteristic vent in the left-hand side of the case where the bells should be. It then occurred to me that they might have been removed to fit the dial. I hope that this isn’t the case, but it seems likely to me, as there would probably not be enough space for both.

Has anyone had any experience with these phones, preferably ones that have been modified with a dial? If it does not have the bells, is there some way that I could perhaps add a buzzer? I would like to be able to use the phone as a pair with the other one I have bought, you see. If outgoing calls could only go one way, that would sort of defeat the purpose of their use for me.

Anyway, if anyone could help me I’d be grateful.

Thanks,
William
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Old 16th May 2024, 5:57 am   #2
dagskarlsen
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Default Re: Advice On Type L Field Phone

May it be like this?
https://www.avenueshopswapandsell.co...housing/349106
The ringer has no gong, but uses the cabinet. (Yellow ring)
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Old 16th May 2024, 7:31 am   #3
Sir_Lunchalot
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Default Re: Advice On Type L Field Phone

Yes, it is exactly like that. The reason I asked on the forum is because I have not had a chance to open the phone up yet. Now that I have looked at the photo you supplied, I notice that in the corner of one of the photos of my particular telephone there is the same setup.

Thanks for the help!
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Old 16th May 2024, 8:29 am   #4
Dave Moll
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Default Re: Advice On Type L Field Phone

I assume the clicking "ring" of Telephone Set "L" is intended to be quieter than the sound of a telephone with gongs. It is, however, quite audible enough, even if it's less likely to give away your location in battle!

As long as the magnetos are in working order, they should be able to signal each other without further modification. The addition of a dial can then be ignored.
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Old 16th May 2024, 9:16 am   #5
Sir_Lunchalot
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Default Re: Advice On Type L Field Phone

Thanks Dave,

As I’ve had no prior experience with these phones, I’m very grateful for your advice. I did not know that these telephones click when they “ring”. Hopefully I’ll be able to hear it myself when my other one arrives.

Also, the magneto is functioning on my current one, reading about 70-80 volts when cranked moderately fast.
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Old 16th May 2024, 9:54 am   #6
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Default Re: Advice On Type L Field Phone

They can also be easily and reversibly modified to take a pair of D cells to power the carbon mic. I used a couple of clip-together plastic cell holders for convenience.

I have a few of them (no dials) - the children had one in each of their bedrooms with the return path through the central heating piping (signal wire over the roof of the house, with the aid of a tennis ball). The fourth one was in the kitchen, for their mum.

You might need to tune the ringer for maximum clatter (bend the arm, probably). The earlier ones I owned had bells, but the 'buzzer' ones were too quiet to be heard above the noise of children playing.

We fixed the problem in the end with a small ship's bell at the bottom of the stairs...
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Old 16th May 2024, 1:36 pm   #7
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Default Re: Advice On Type L Field Phone

Greetings all.

Hello William.
The phone you have is not an "L" type phone.
The one you have with the dial was not generally used by the armed services.
It was used here in Australia as a linesman's test phone.
As you have correctly observed your phone does not have the vent on the front left side of the box. The test phone does not have the vent.
The test phone,"Bag Set" was common from the early 50s to around the mid 70s in country line depots.
Used by the linesman working on aerial phone lines in country areas.
We all knew it as a "Bag Set". Not sure of it's official name. Really testing my memory from such a long time ago
Obviously there will be exceptions but safe to say not used in city areas.
Some of the old hands had WW2 "L" sets but they became a hindrance as more and more areas were changed over to automatic phone systems
The dial was from the factory also the ringer setup is from the factory as well.
There is no adjustment on the ringer. It just makes a clatter which is reasonably loud. I could hear mine above passing traffic so it did the job.
These phones were made here in Australia as well as the UK.
The one in the pic from dagskarlsen I am guessing was made in the UK as it has a Hunt's capacitor clearly showing.
I have a couple here made by Plessy and I think from memory at least one other made by Ericsson.
These are a solid, robust phone. Looked after they will last for years.
Just one easy point, take the microphone element out occasionally and give it a shake. You should be able to hear the carbon granules shaking inside. Do not rap the microphone on hard objects as each time you do it turns some of the granules into powder. Bang it often enough and you will throw it in the dustbin.

Enough of my chatter.
Cheers William and cheers to everyone else.
Robert.
VK2BNM.

Last edited by QQVO6/40; 16th May 2024 at 1:56 pm. Reason: Changed wording.
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Old 16th May 2024, 1:57 pm   #8
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Default Re: Advice On Type L Field Phone

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Originally Posted by QQVO6/40 View Post
Hello William.

The phone you have is not an "L" type phone.
Given that it's not a 'L' Type does it have an official designation?
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Old 17th May 2024, 12:04 am   #9
QQVO6/40
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Default Re: Advice On Type L Field Phone

Hello everyone.

And hello Graham.

You have set me a real challenge!
Come on Graham. Stop laughing!! If you could see my workshop!

We always referred to these phones as a Bag Set.
I can not recall the official designation for them.
Used predominately by outside lineys. Aerial linesmen.
They were like a transition test set going from the old manual magneto system to some country towns had the common battery system and the full automatic phone system.
These Bag Sets worked with all three quite ably and were very well made as well.

I have a couple of places to look to see if I can find the official name for these phones.
I can dig out a couple of the phones to see if there is anything on them. Take the bottom off to see if there is anything on the circuit label.
Next I will look at a couple of books. When I find them.
The Australian Post Master Generals Department had a number of information publications.
Bound books used in the training schools, A4 books used by "techies" (technicians in the telephone exchanges) and small reference books used by the lineys.
The reference books used by Techs and lineys were of a loose leaf format. When amendments or updates were published we were expected to remove and discard any pages to do with obsolete equipment.
This is the main reason why there is not much information about this older stuff.
I have a "Substation Equipment Handbook" that would have been used by a phone install tech and it might have some info in it.
Also have a couple of "Aerial Lines Handbooks" that may have a reference to the Bag Sets.

You know when somebody asks a question and it torments you till you have an answer. Something that I should probably know but can not remember. It won't dominate my life but I just need to find out.

The cabinet that holds these books has about half a ton of gear in front of it.

Stop laughing Graham!

Cheers Graham.
And cheers to all.

Robert.
VK2BNM.
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Old 17th May 2024, 5:06 am   #10
Sir_Lunchalot
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Default Re: Advice On Type L Field Phone

Thanks for the information Robert, I had no idea that this one of mine wasn’t an ‘L’, as I had just assumed that it had been modified. Fortunately for my war memorabilia-loving side, I still have an actual type L on the way.

I suppose that as they are both very similar they will have no trouble calling each other on a simple two-phone setup.

Also, about the location of manufacture, my Bag Set was said to be of Plessey manufacture by the seller, but I am not sure how to confirm that. I haven’t opened up the case yet, but I was planning to do so just to check the soundness of the wiring, though I’m sure it will be in working order.

Lastly, I was not aware that it was not good to knock the microphone against another object. I’ll keep that in mind, and in the meantime I’ll give it a shake and see what I can hear.

Thanks for all of the help,
William
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Old 17th May 2024, 5:10 am   #11
Sir_Lunchalot
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Default Re: Advice On Type L Field Phone

Quote:
Originally Posted by Simondm View Post
They can also be easily and reversibly modified to take a pair of D cells to power the carbon mic. I used a couple of clip-together plastic cell holders for convenience.

I have a few of them (no dials) - the children had one in each of their bedrooms with the return path through the central heating piping (signal wire over the roof of the house, with the aid of a tennis ball). The fourth one was in the kitchen, for their mum.

You might need to tune the ringer for maximum clatter (bend the arm, probably). The earlier ones I owned had bells, but the 'buzzer' ones were too quiet to be heard above the noise of children playing.

We fixed the problem in the end with a small ship's bell at the bottom of the stairs...
Thanks Simon.

The one I have currently already has a d-cell holder installed, but I will certainly install one in my actual type ‘L’ that is still on the way. I’ll be very excited to try the phones out as a pair.

I’m glad that the ship’s bell did the trick!

Thanks,
William
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Old 18th May 2024, 12:24 pm   #12
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Default Re: Advice On Type L Field Phone

Hello again everyone,

I have just two other questions that I would like to ask. I think that these are my last two.

Number one is of probably little consequence, but I would like to know whether these phones operate best with any certain gauge of wire. I was looking at maybe getting 14 gauge, but I’m not sure if that would be too thick? Hopefully someone can shed some light on this for me.

I believe that I know the answer to the second question, but I shall ask it anyway. Keeping in mind the great changes that have been made to landline telephone systems over the past 70 years, I was wondering if it would be somehow possible to connect my ‘Bag set’ to a modern landline system. I seem to remember that normal rotary phones need some sort of adapter, but I was more wondering about the voltage in modern lines. Is it theoretically possible to connect it to a modern telephone line?

As I said, I suppose that it is not possible, but I wouldn’t know if I hadn’t have asked, so there it is.

I extend a great thank you to everyone who has responded to this thread so far. You’ve all helped me learn a great deal about what I have, and how exactly it works.

A great thanks,
William
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Old 18th May 2024, 1:58 pm   #13
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Default Re: Advice On Type L Field Phone

First, the gauge of wire is unimportant, as the currents involved are very small and apart from ringing, so are the voltages. In any case, this only affects the minimum, so thicker than needed is fine. As an example, I tend to use speaker-type twin flex to interconnect my field telephones, but something much thinner would suffice.

Second, yes, it is possible to connect these to the telephone network, though not necessarily advisable nor legal. Regarding the latter, I don't know the regulations in Australia. The important thing if you do is never to wind the magneto, as injecting the ringing into the network is not a good idea.
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Old 19th May 2024, 7:36 am   #14
Sir_Lunchalot
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Default Re: Advice On Type L Field Phone

Thanks again Dave. I wasn’t really planning on attempting to connect my phone to the network. It was more idle curiosity that drove me to ask the question.

Thanks also for the advice on the wire type. I think I’ll go to my nearest electrical supply store and see what they have.
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Old 9th Jun 2024, 12:15 pm   #15
Sir_Lunchalot
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Default Re: Advice On Type L Field Phone

G’day again everyone,

I’ve just got around to doing some work on the two phones today, and have discovered a few things that I thought I should ask about.

1: Having surveyed the inner workings of the ‘Bag set’ and finding everything in (apparently) working order, I connected up some batteries (two D-cells in series, using the original holder). I was unsure as to how I should test it, so I just followed the instructions on my 1944 Type L in the hope that due to their similarities the same test would work on this one. In case anyone is unaware of this procedure, I shall detail it here.

First, I shorted the two terminals (L1 and L2/E) with some wire. Next, I depressed the PTT and blew into the microphone. To my satisfaction, the blowing was reproduced perfectly by the speaker in the handset. The second half of the test is to remove the short. With the L type phone, it says that the sound from the speaker should be altered (it doesn’t specify in what way). I forgot to perform this half of the test.

Anyway, later on I wanted to demonstrate my success, so I put the batteries back in, depressed the PTT again, and once more heard my own blowing being reproduced. The only problem was that the terminals were no longer shorted, and I assume that I should not have been hearing what I was.

I hope that this is what should happen, but I am not sure. Does anyone know, or have any ideas?

2: Dad and I had a go at fixing up my 1944 Type L as well. Although we weren’t successful today with getting it working, we fixed up a few things such as re-soldering a wire that had come loose, and fixing some insulation. When we went to test the handset, in the same way as before, there was no sound in the speaker. After doing a bit of probing with the multimeter, we discovered that the contacts on the PTT were dirty, so we quickly cleaned them up.

We then tested the handset again, expecting our problems to be solved. To our surprise, it was still not working. After probing around with the multimeter again, we discovered that there is a short between two of the wires in the handset cable. Unfortunately, we ran out of time to investigate it further, but we’re going to have another look at it soon.

Anyway, my question is, is this likely the culprit of the problem? I know that it is difficult to answer without examining the phone, but any insight is welcome.

I’m very grateful for all of the assistance and advice that I have received so far!

Thanks,
William

Last edited by Sir_Lunchalot; 9th Jun 2024 at 12:19 pm. Reason: Spelling
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Old 9th Jun 2024, 1:31 pm   #16
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Default Re: Advice On Type L Field Phone

Quote:
Originally Posted by Sir_Lunchalot View Post
Anyway, later on I wanted to demonstrate my success, so I put the batteries back in, depressed the PTT again, and once more heard my own blowing being reproduced. The only problem was that the terminals were no longer shorted, and I assume that I should not have been hearing what I was.
Actually, it isn't necessary to short out the line terminals for sound into the transmitter to be heard in the receiver, so your set is probably working fine.

Quote:
Originally Posted by Sir_Lunchalot View Post
we discovered that there is a short between two of the wires in the handset cable [of the 1944 Type L]. Unfortunately, we ran out of time to investigate it further, but we’re going to have another look at it soon.

Anyway, my question is, is this likely the culprit of the problem? I know that it is difficult to answer without examining the phone, but any insight is welcome.
It's quite possible that a short (especially if across the receiver or transmitter) would cause the symptoms you describe.
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Old 10th Jun 2024, 7:45 am   #17
Sir_Lunchalot
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Default Re: Advice On Type L Field Phone

Thanks Dave, I didn’t know that the terminals didn’t need to be shorted for sound to be heard in the receiver. It seems that the phone is in perfect working order, then!

As to the short in the other phone, we initially thought that it was occurring in an easy to fix place, where the cable meets the handset plug. I’m now thinking that it could be in a much more difficult spot - halfway up the cable in a partly frayed area. If that is the case, I’ll have to devise some way of isolating the two wires without damaging the cable. A job for the weekend I think.

Thanks again,
William
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