Field phone and switchboard inter-operability

[Gary_GJK]

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