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Vintage Telephony and Telecomms Vintage Telephones, Telephony and Telecomms Equipment |
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30th Mar 2015, 1:04 am | #1 |
Dekatron
Join Date: Nov 2009
Location: Lincolnshire, UK.
Posts: 5,000
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Some GPO 332 questions
I have a couple of 332 telephones as ornaments stood either side of a set of vintage scales on top of a cabinet in the living room. I’ve had these phones for many years and they were both in use and connected to the ‘system’ until 1999 when I lived at my old house on the Fens. A young (15 year old) relative was round the other day and he’d never seen or operated a dial type phone, so seeing as one still had the long lead and plug coiled up behind it, I decided to get it down and plug it in so that he could have a go at using a vintage phone. I knew it would likely work as I’d connected it up once before since I moved to this address. I got him to phone home to his mother and when she didn’t answer (she’d gone out as it happens) I told him that the reason that there was no answer was because he was calling on a vintage phone that was probably from the 1940s so his mother hadn’t been born at that time and also their house wouldn’t have been built then – for a moment he almost believed me!
The next day I cleaned the contacts operated by the handset as these were slightly dirty which I remembered from when I used to use this phone at the other house, but otherwise the phone works perfectly, other than having the typical ‘carbon granule’ microphone outgoing sound. I’m told that the sound is ok, but just not as good as my (now becoming vintage) Cable & Wireless CWR500 phone. What I need to know is – what microphone do I need as a modern replacement for the one that’s in this phone, can I make or adapt something, or is the one in the following link the type that I need? http://telephonelines.net/index.php?...02ccup7s9s0ip4 I don’t mind doing a modern ‘reversible’ modification to this phone as I think I’ve got a box of old phones in the loft and probably have some more of these phones anyway. I’ve been doing quite a bit of reading on these phones over the last few days and whereas I had always thought these phones dated from the 40s or perhaps as late as the 50s, I was quite shocked to find that the handset had T.E’37 in the oval indicating that it was made in 1937 – the other phone has a 1936 code on the handset and, as yet, I don’t know about the others in the loft. Now here’s a question that I can’t find the answer to – the stamp on the bottom of the phone indicates that it was factory refurbished in Wales in 1964, but could the handsets, phone cases and other parts all be mixed up during refurbishment? Also, can a case be dated (I know the dial can be dated, but I haven’t removed it yet to check as the phone is now connected up and in use) and also, is it possible that the original square type condenser could have been replaced for a round type in the 1964 refurbishment? The handset ‘pushers’ have the metal outer insert, which indicates an earlier case, but earlier than what date exactly? Below is a picture of the chassis:- |
30th Mar 2015, 8:11 am | #2 |
Dekatron
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 6,127
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Re: Some GPO 332 questions
The electronic Transmitter 21A (as shown here) is designed as a direct replacement for the carbon granule transmitter of a 700 series 'phone, but can be used in a 200/300 series by removing the outer case and adding hook-up wire between the screw terminals on the transmitter and those in the handset. You may need to remove the pin on which the original transmitter would sit.
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30th Mar 2015, 1:39 pm | #3 |
Heptode
Join Date: Aug 2009
Location: Worthing, Sussex, UK.
Posts: 661
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Re: Some GPO 332 questions
Only the red type can be used in this way. The blue type is of different construction and hence cannot be reduced in size.
I have done this to a couple of my phones and the improvement in sound quality is very much worthwhile. Best wishes. |
30th Mar 2015, 5:57 pm | #4 |
Octode
Join Date: Mar 2011
Location: Sheffield, South Yorkshire, UK.
Posts: 1,453
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Re: Some GPO 332 questions
Telephone Lines also do another type of electronic microphone that appears to fit into the Handset 164, and they are a bit cheaper than pusser 21As. See: http://telephonelines.net/index.php?...roducts_id=810
I can't actually recommend them, though can the supplier, as I've never used one; I make my own as needed. - Joe |
30th Mar 2015, 8:12 pm | #5 |
Dekatron
Join Date: Nov 2009
Location: Lincolnshire, UK.
Posts: 5,000
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Re: Some GPO 332 questions
Thanks for the replies so far.
I had in fact seen that lot of five for sale in the link, Dave, but it’s a bit of a chance that they’re not all faulty ones that have been removed from old handsets and put in a box somewhere, to be found a few years later – a bit like boxed valves. I think I’ve got some 700 type phones in that big box in my loft, so I’ll have to see if I can easily get to it and have a look at what’s in it. I may be able to ‘borrow’ a microphone transmitter from one of them. That’s a good bit of information for me to keep in mind, John. Joe – I think I got the link to that website in my first post from a post of yours on another thread in this section while I was researching the subject, but I hadn’t seen the insert that you linked to in your post above. Lots of food for thought, but I’m rather keen on this ‘making my own idea’. I’m no phone expert (yet) although I’ll probably be well on the way by the time I’ve finished! I’ve been looking at these ‘Electret’ mic inserts. There’s a lot of them for sale and some ‘look’ slightly different to others, and with different prices, too. I have to admit that I don’t know a lot about them, so are they all basically the same and what’s the word on fitting these to a 164 handset? Here’s a link to one I was looking at just now:- http://www.ebay.co.uk/itm/Sub-miniat...1#ht_415wt_721 I enjoyed using the word ‘condenser’ rather than capacitor in my opening post, but I find it hard to believe that the chassis shown in this phone dates from the 1930s. While I had the phone apart I took some other pictures, so below is one of the other side of the chassis. Any idea of a realistic date? Also, do the original junction boxes have date codes? Surely the one shown below doesn’t date from April 1920? |
30th Mar 2015, 10:36 pm | #6 |
Octode
Join Date: Mar 2011
Location: Sheffield, South Yorkshire, UK.
Posts: 1,453
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Re: Some GPO 332 questions
An electrect microphone on its own won't work without supporting circuitry.
Here are details of one I made to rebuild a Number 16 transmitter, the type used in 700 series 'phones before the 21A came out. Below are pictures of the same circuit fitted in a Handset 164. The bit of card is to stop the Bakelite cover from rattling and the white disk is packing foam which protects the electronics from being spit on. I also lacquered the PCB after photographing it. - Joe |
4th Apr 2015, 3:05 am | #7 |
Dekatron
Join Date: Nov 2009
Location: Lincolnshire, UK.
Posts: 5,000
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Re: Some GPO 332 questions
Many thanks for that, Joe. I thought it would need to be something like that. You’ve certainly made a very good job of your module. Do you know if the circuit you’ve used is the same or similar to the circuitry used in the microphone unit shown in the link in my first post?
As for the question about the junction boxes – from doing some research it seems that the number is a part number and not a date and they probably date from the 1950s. Well, I’ve spent some time in the loft this last few days, finding all sorts of everything. I’ve found some phones, some I knew I’d got, some I’d forgotten I’d got and some I thought I’d got, but don’t seem to have anymore. I found another two 332 phones (so that’s four of those now), a 746, a 741 wall phone, some push button phones from the 80s & 90s and also the odd vintage answer-phone unit (perhaps have to start a thread on those sometime). An observation I’ve made is that it seems there is no way to properly date any of these 332 phones from before the 1950s, unless the phone has managed to escape the routine ‘factory refurbishment’. Looking at details of these phones on the net, the only ones that tend to have the date of manufacture stated are ones from the 50s or the very late 40s. I think that this is due to the fact that production stopped in 1959, so these last generation phones were still too new to be taken away for refurbishment before they would be replaced with the newer 700 models. I could imagine that in the Wales factory there would be a line of containers and the phones would come in for refurbishment where all the parts that were still good would be placed – all handsets, all cases, all chassis, all dials etc. etc. So I think that all the parts just get jumbled up, indeed, the handset on one of my phones is dated 1934, which is before the 300 series phone was made in the UK, so it must have come from a 200. I've also noticed on the first phone that the screws are all different with different depth of slots between the same type of screw showing that these are even from different batches. This, of course, is all guesswork on my part, but it seems logical from the evidence. Both of the original two phones that I had as ornaments plus one from the loft were ‘Factory Wales Refurbished’ with refurbish dates of 1963, 64 & 67 with handsets of (in the same order) 1936, 37 & 34. These are all what I think are the Mark 2 pre-facelift models due to them having the sleeved plungers beneath the handset. If I look very closely with a magnifier it looks as though there are very small chips around where these sleeves are inserted – indicating replacement or modification, anyone else noticed this? One of the phones that I’ve retrieved from the loft is an original and is dated 1956 and also its handset is dated with the simple 164 56 in the ‘oval’ and has the up-dated plungers without the sleeves in the top of the case. This phone is marked as a CB (central battery) model so should have no dial, but one has been fitted at some time. This dial is unusual as it has a much ‘fatter’ than normal and black painted finger stop, although it’s right next to the ‘0’ where it should be. I removed this dial, as, like the other phone from the loft it was a little noisy on return so needed a few drops of instrument oil. It’s a ‘No 10’ dial but I couldn’t see a date on it. I’ve had this phone connected up and it seems to work fine. Infact, I’ve had this one and the first one described in post #1 connected up together with one other normal phone and what I find is that when dialling from either one of the 332 phones is that one will make the bell ‘jingle’ on the other but not affect the normal phone – so I’ll need to look into what’s causing this. All three phones are happy to ring together, although I don’t know how many of these 332 type phones I’d get away with on one line – none of them have any ‘resistors’ added! I’ve had these phones for over 40 years and until a few days ago knew very little about them. They really are a great design and although most folk seem to re-fit the cloth covered handset leads, I quite like the 50s & 60s curly leads that these have fitted and think there’s less likelihood of pulling the phone off the table and onto the floor with them. The two phones that have been in the living room have never really been in storage as such as I’ve had them in some sort of use up until 1999. The other two phones from the loft I’ve never used. The 1956 phone described above has obviously been splashed with paint from an ‘old time’ careless decorator. As well as the spots still left on the case, it looked as though there had been some really bad splashes that someone removed with a sharp instrument or maybe even sandpaper. The first picture below shows the really bad scratches to the front left area of the case. I spent a happy hour outside on Thursday with the phone on the garden table and with some cutting paste, removed all but the very deepest of the marks, finishing off with some 1970s ‘Jove haze remover’. Then I spent another happy hour with paint thinners on the junction box that was covered in paint, well, you need a 'period' junction box on a period phone! The phone has come up quite well, as shown in the second picture below. Now it probably needs a bit of a wax polish to finish it off properly. You can just see the fatter, black finger stop on the dial, which seems rather rare as far as I can see. The third picture shows the back of the dial – any thoughts on this dial? The last picture shows the chassis from underneath:- Last edited by Techman; 4th Apr 2015 at 3:31 am. |
4th Apr 2015, 10:41 am | #8 |
Octode
Join Date: Mar 2011
Location: Sheffield, South Yorkshire, UK.
Posts: 1,453
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Re: Some GPO 332 questions
The electrect you flagged up would work in that circuit but would be a bit tricky as it doesn't have long enough wires on. Below is a picture of the type I used. They cost £1.05 for eighteen.
- Joe |
24th Apr 2015, 8:34 am | #9 |
Heptode
Join Date: Jun 2006
Location: Ware, Hertfordshire, UK.
Posts: 988
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Re: Some GPO 332 questions
Hi Techman,
the best place to buy the modern replacement microphones is here:- http://antiquetelephones.co.uk/conte...uk/d12_01.html It is interesting to look at their Trimphone replacement microphone which uses an electret insert (the Trimphone used an awful tiny carbon microphone):- http://antiquetelephones.co.uk/contents/en-uk/d12.html Regarding phones and originality. Yes the GPO did mix up all the bits when they refurbished them. Generally if you want a phone as made then you will be looking for at least all the case parts to have the same manufacturer's mark. Inside the case for instance you will find a marking, sometimes within a small circle, with a part number, sometimes the year of manufacture and a manufacturer's ID letter, eg:- S for Siemens PL for plessey PX for pheonix H for ATM C for GEC E for Ericsson W for STC Pre-war GPO handsets have a manufacturer's mark in the oval, but post-war they don't Generally the workings of the phone would have the same manufacturer's mark, but not all of them made the internal parts. Pheonix for instance made cases and chassis, but not dials (they used GEC dials). Anyway dates on parts should be within a year of each other. The sleeved plungers with plain metal ends on the underside were MK1. To improve them they made the later addition of putting a thread on the end to which a small nylon cup was screwed (this is quite rare). The MK2 plungers were not sleeved, but worked in conjunction with two small rollers on the switch hook lever on the chassis. You can tell if the switch hook lever has been changed as the MK1 chassis has two pieces bent upwards to provide a limit to the downwards movement of the lever. The MK2 chassis relied on two downwards projections at the rear of the lever, so if you see both downward and upward projections then you have a MK1 chassis with a MK2 roller leaver. However that fact that the GPO mixed the bits up means that you can always make a bitsa phone without affecting its value (though not a good idea with coloured bakelite). Also if you have a phone refurbished in the 60's it is likely to have a much blacker case as the GPO only kept the best bits. The black backed dial is rare and would be off a candlestick or a 162, originally having a black solid copper fingerplate. The number 20 on the terminal block indicates the type and the '4' indicates the number of terminals. It is officially a BT20/4 where 'BT' stands for block terminal. The early bakelite terminals were one piece with terminals being accessed from the rear, the rear cover simply being the wall it was screwed to. Sorry for the long post, hope it answers some questions... Cheers Andy Beer
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