g43 RTTY and telex equipment
A. Antenna topics
B. Amateur radio equipment
C. Technical reflections (Reflecties door LA8AK)
L. VLF, MF and 136kHz equipment ideas
M. Measuring instruments and tools
German office telephone Emy41
Post-War and Pre-War bunker telephones, the post-war type is a heavy beast! Either was available with and without dial
Jack stripe from German telephone switchboard
Ordinary German field telephone (1933) with adapter for use towards an remote battery line (SB-zusatz),
probably not for ATE since it is no dial (or is the dial the 2nd accessory?).
Circuit diagram for the German field-telefon
Circuit diagram (Schaltbild SB-Zusatz 33); Switch, capacitor and audio choke
The basic circuit for balancing a telephone in a two-way circuit with minimum sidetone is derived on the wheatstone bridge.
Balance is achieved when the transmitted audio doesn't return to the receiver. Normally such simple circuit will have a
practical balance of 20-26dB, but the normal telephone subscriber line has an impedance of 620W in series with 1µF
and 47nF in paralell (see below). Reference.: Phone patch hybrid circuit.
Lumped 700W (800Hz) equivalent to a standard telephone subscriber line in Europe, 620W in series with 1µF and 47nF in paralell
Telephone Subscriber switchboards
(Refr: Telefoni til bruk i Telegrafverket, III. DEL, 1953)
33b. Carrier frequency systemst for telephones
Some items have been moved to page 33b.
Riksvåpen for fjellstuer (Telegrafverkets linjeopsynsstuer) - antakeligvis noe lignende av hva Veivesenet hadde bl.a. på Håhelleren.
EB/LME switch for telephone exchange type AGF (OS)