Field phone and switchboard inter-operability
 

I hope a query about line equipment is permissible in a wireless forum!

I am trying to shore up my understanding of line equipment as found in British and Canadian units and formations, particularly for the 1943-45 period. I've not been able to find a single, ideally contemporary, document covering the queries I've set out below, and the myriad pamphlets and working instructions are scarce and expensive - especially for a mechanical idiot like me who can only really comprehend the 'general description' page.

My interest is in the practical/tactical application of signal equipment from Division level down, and knowing what could connect to what is important in defining who could speak to who.

I have been trawling the internet for bits and pieces of info and would appreciate any comments on whether I've at least got the basics right in deciphering which types of telephone were (and were not) compatible with certain switchboards.

Telephones -

Set D Mark V; the field telephone in service in 1939 and remaining so throughout and after the war. Capable of transmitting morse as well as speech. There are a couple of things regarding the D V that I have only recently found myself querying.

It had a buzzer and could only call other phones and switchboards able to receive a buzzer signal. I understand that included the Telephone F and the Switchboard UC6 and UC10 - I don't think it included the Telephone L or J or the Switchboard F & F - is that correct? Also, I found a mention that the 'aural indication' of an incoming call was a buzzing through the handset, is that correct? I have seen the morse key demonstrated as being the means to buzz another phone or switchboard; was the buzzer also used to receive morse transmissions via the handset?

Set F; had no morse capability, being speech only. It had a magneto and could call other telephones or switchboards with magneto receiving capability, and also had a buzzer so could communicate with a D V. A high power version of the F with amplifier available for longer distances, seemingly phone to phone rather than via a switchboard.

Set L; later war telephone, speech only, I think initially intended for linemen but latterly issued as unit equipment. I think this only had magneto call/receive, so could not operate direct to a D V unless via a compatible switchboard?

Set J; late/post war period, designed for tropical climates, otherwise same outline as for L.

Switchboards -

Universal Call; 10 or 6 line versions, could receive calls by magneto (as in Tel F) or buzzer (as in D V).

Switchboard, magneto, 10-line (WD); late war development for tropical theatres, which dispensed with the buzzer so could not receive from a D V, only from magneto phones. Required a phone L or J to be connected to it for operator use.

Switchboard, F & F (field and fortress); used in Div Sigs Operating Sec/Tp.
Built up from a 5-line unit, with four units housed in a cabinet to make a 20-line switchboard; could have one, two or three cabinets so fitted giving 20, 40 or 60-line capacity. I think this only worked to magneto phones, so fine with the F, L and later J telephones but not the D Mark V.

Any comments appreciated.

Thanks,

Gary

some chatter on postwar field telephones
 

The postwar TA43 field phone has two wires and two flashlight batteries. There is a push to talk switch on the handset, and no data capability by itself.

https://radionerds.com/index.php/TA-43~PT

I do know there was a switchboard that had patch cords for sending calls from scattered stations to one point, and directing the calls where needed.

The C42 radio had a handset that fed with WD1 phone wire to a junction box on the top tray. The remote had a thumb operated magneto on the handset which rattled a clacker in the junction box, and whoever was on radio watch could speak to the remote. I don't know if it had batteries or used the C42's power.

Hi Gary,

Pre-WW2 was mostly buzzer call instruments: Telephone Sets D Mark III and III* in leather cases, and a 10 line exchange (Buzzer Switch Unit 7+3). (For working in the "Danger Zone" (within about 3000 yards of the enemy lines) the Fullerphone (a Direct-Current telegraph instrument - morse only) would be used to prevent interception by the enemy (this was "point to point" only, it had no "calling features" and couldn't work through an exchange.

WW2 saw the introduction of Telephone Set D Mark V, with buzzer calling and buzzer or magneto answering. It could do morse code or speech, but was still interceptable, so the Fullerphone was still used if interception was likely to be a risk.

Linemen continued to use the D Mark III or a GPO 110 telephone for portability.

The "Office Telephone" for higher formations was Telephone Set "F", which originally supported buzzer and magneto calling, but later had the buzzer replaced by an "induction coil" (audio transformer) for better speech quality.
(The Telephone Set "F" High Power was for use on long lines and had a valve audio amplifier built in (separate battery boxes required)).

There was also Telephone Set 'H' in the same casing as the "F", which was "sound powered" (dynamic inserts for microphone and earphone) for short distance use (rifle ranges and coastal guns, etc.)

Telephone Set 'L' in a pressed steel case replaced the Linemen's phones. It was more robust but not waterproof and was later replaced by Telephone Set "J" which was fully sealed and tropicalised - this also replaced the "D" range as the Army dropped buzzer signalling from newer equipment.

Switchboards:

Universal Call 6-line and 10-line were used in forward areas, they supported buzzer or magneto signalling and are reasonably portable.

F&F (Field and Fixed) was a modular exchange that could be broken down for transit. It could also be connected to the GPO telephone network. (I can't put my hand on its manual right now, and can't remember if it supports buzzer signalling - depends on whether the indicators are sensitive enough.) It was basically an "Office" exchange for headquarters that was light enough (Ha!) to be taken into the field, as well as being used in fixed installations and vehicles.

Magneto 10-Line (WD) was a later (magneto only) switchboard that was waterproof. It required a separate telephone (usually a 'J') for the operator.

Various "Wireless Remote Control" units could also act as magneto telephones.

The 19 set group has most of the manuals if you need more detail.

Best regards,
Chris.

Telephones
 

Most of the WW2 era British pattern field telephone equipment was also manufactured outside of Britain. Australia and Canada ( and N.Z. ? ) built copies of the field phones D mk V and switchboards.

I have a Aust. made Telephone F , have also seen L phones . Here, the Postmaster General (PMG) , operated the govt. owned communications network, the PMG operated their own factories where many thousands of wartime field phones were manufactured. The PMG ran just about everything, from the telephone system to amateur radio licensing and exams.A friend did his radio tech. apprenticeship in the PMG during the 1960s.

Used to buy D mk 5 phones for $10 but the recent prices have been going through the roof, up to $200. Just recently I spotted two "A" remote control units at $125 each, Aust. built for the W.S. 11.

I've seen many Australian built field sets that were supplied with a die cast alloy case, over time, the alloy corrodes into a white powder substance. Don't know if the alloy cases were also seen in other countries ?

Yes, the British Empire/Commonwealth meant that lots of equipment was designed in the UK, then manufactured (where possible) for local use in other countries. I've got (I think) New Zealand made signals kit, an Australian tripod and bomb disposal telephones, and US and Canadian manufactured WS19s and ancillaries.

Changes were made for local manufacture: the Canadian Telephone Set 'D' Mark V has an aluminium (rather than steel) case, and the WS19 aerial base spacer is made of plywood (with cork gaskets) rather than rubber.

Prices have gone through the roof over the last few years, partly due to scarcity, but also due to people taking auction prices (where two people desperately want a particular item) as the actual value. Then there are the dealers (and optimists) waiting for the One True Sucker to appear and make them rich... :(

Canada made aluminium cased kit, because they had hydroelectric power to run aluminium smelters, and also wooden instead of rubber parts for similar reasons: locally available materials.

There's stuff I want for the collection available in Australia (Bags, Telephone Receiver - the forerunner of the "Satchel, Signals"), but shipping costs have also gone through the roof.

Too much stuff got melted down as scrap or buried in landfill. :(

Best regards,
Chris.

I think the remote handset is entirely passive, and powered from the J1 or J2 box in Wireless Harness 'B' (soft-skinned vehicles) or the equivalent in AFVs. (I must sort my library into some kind of order; I can't find the appropriate manuals at the moment.) The buzzer or other tone generator is in the J1 control box (from memory).

WD1 is identical to D10 cable. (D9 never made it into service, I can't remember exactly why, but suspect the insulation wasn't robust enough, and why D10 had a protective outer layer of Nylon over the PVC. The earlier telephone cables (D1 to D8) were a cloth-covered rubber insulated type, with wax (Ozokerite?) impregnated jacket. I've got the details somewhere.) :)

Chris.

I have recently acquired various field phones and trying to sort out the same questions
I have 2x 1918 model.D mk2 buzzer units....extremely fragile due to age.......but I think I will get them going.......L1 ..and then CL and then LorE..........three connections has got me lost
Have a model L that works and about 4x Model F mk2 that work.( trying to get another Two working)
I am guessing buzzer phones may still ring /buzz bell on some magneto phones.
Have Australian 10 line no2 switch board.......similar to the UC10.
Relay indicator flaps on switch board are very sensitive.........buzzer phone should trip them.
This is all a new item of learning for me.........challenge to get them working.
Ron.

Thanks all for the above, especially Chris for going through the various types of phone and switchboard. I'm still hoping to finish my write-up for WW2 era Inf and Armd Div Sigs, and having spent a lot of time on wireless realised I hadn't put much effort into line equipment. The differentiation between buzzer and magneto calling/receiving was something I only recently recognised and encouraged me to go dig more into the subject.

Cheers,

Gary

Ah! This is fairly simple:

L1 is the telephone line
L or E is the other telephone wire if it's a pair, or Earth if you're using a single wire and earth return (wire to a ground spike "Pins, Earth, Small" or the "heel attachment" on one of your boots - the latter was mainly for line-laying parties).
CL is "Condenser to Line" - for "piggybacking" a telephone circuit on a DC Telegraph wire (usually railway telegraphs in the outer parts of the Empire); it blocks the DC signalling voltage and prevents interference to the Telegraph or the telegraph traffic causing interference to the telephone.

There should be circuit diagrams for the D2 in "Instruction in Army Telegraphy and Telephony Volume 1 - Instruments" the second (1916) edition is probably the best. WS19 group has a copy in the archive. (I've still not found the Signal Training Part III (Instruments) that followed it.) :(

https://royalsignals.org.uk/signals.htm

(Follow the instructions on the main page when requesting documents; it's a bit fiddly due to relentless abuse by various pirates, etc.)

This is very unlikely. The early "Buzzer Switchboards" used a "Watch Receiver" (i.e. earpiece) to alert the operator. The Telephone Sets 'D' (all marks) were similar, with a single earpiece on a headband for the operator to wear continuously. The D Mark V added a magneto bell for compatibility, and the Mark V* deleted the single earpiece (and should have a wire link across the terminals or the handset earpiece won't work).

The Switchboard "Universal Call" (6 or 10 line) was designed to work with both buzzer and magneto calling, but the relays/indicators need careful setting up - there should be "go" and "no-go" resistors clipped inside for setup purposes (to ensure the indicators operate with a buzzer call).

Have fun! :D

Chris.

Thank very much for those gems of information
Regards
Ron.

Set D
 

Attached is a 1941 image of some Set D Telephones in use by the RCA in England.

Attachment 139858

Hmm... three Telephone sets 'D' Mk.V (which look like the Canadian version with cast-aluminium rather than the British pressed steel cases), something I don't recognise but may be a small buzzer switchboard[1] for the telephones, and an Apparatus LoudSpeaking on the right, with two 6V 85AH accumulators to power it. It's the 4-channel version, so probably for a 4 x 25pdr gun battery.

Nice photo. :D

Chris.
[1] Somewhere I have a "3-line switch unit", allegedly for Artillery use, but it has Kellogg keys and doesn't (I think) look like the one in the photograph. So: a phone for each member of the team plus the ALS for the Gun Position Officer, and presumably lines to the FOO and the unit commander?

1st Medium Regiment, RCA
 

In 1941 the 1st Medium Regiment was equipped with B.L. 6-Inch 26 cwt Howitzers.

Attachment 139859

I know a fast way to dull any knife is to try to cut WD1 wire! And yes, I think it was the J1 box on the C42. It's been a long time since I had to remember those designations!

D10 (or WD1) is four strands of tinned copper and three strands of tinned steel wire as I recall. It's hard to cut even with the approved tools (Pliers, Side-Cutting or Diagonal Nippers - and I can't remember if the Hellerman Jointing Tool had a dedicated cutter built in (I suspect it must have)).

Earlier field cables also had steel strands for strength (and copper for conductivity), and I suspect the change from 5-inch Pliers, Side Cutting to the 8-inch version (that necessitated the issue of a larger "Pouch, Tools, Lineman") was due to the difficulty of cutting the later cables with the lower leverage of the 5-inch ones. (There were also pliers with replaceable cutting jaw inserts at one point!)

Chris. (I remember making the (time consuming) "bound-in" joints, and having to insulate the thing with fabric tape, then waterproof the whole bodge with self-amalgamating rubber tape. I also remember the "Self-Soldering sleeves" that were quicker to use but not as robust. The Hellerman crimp sleeve joints were much faster and more reliable.)