E44 Swedish TFNAPP MT (m/37), 1966

Описание: Visit http://fieldphones.org/episode44/ for additional information.

Developed by Ericsson pre 1935 and introduced by the Swedish army in 1937 as m/37. The Ericsson catalog off 1939 lists 4 device types: DPA1001 (LB only), DPA1102 (LB/CB, line test button), DPA1152 (LB/CB with included dial) and DPA13, LB/CB with included telegraphy buzzer. The Swedish army introduced DPA13 as m/37A and DPA1001 as m/37B. After WWII it was updated with an integrated hook switch (only active in CB mode) and an adapter for standard IEC R20 (D-Cell) type batteries and called m/37-47. Later it got the designation TFNAPP MT (TFNAPP = Telefonapparat = telephony device, MT = ? Militär-Telefon ? ? Mobil-Telefon ? ? Med Tillbehör ?). The model or derivates of it were also used in other countries armies, e.g. in Denmark as FTLF M/51 and in Finland as P-1-7A/VPAR [6]. More than 100k were manufactured up into the seventies, the instrument was/is still in use in the Swedish Army in the 21st century.

Sources often mention that it is designed based on the German FF33. I doubt that, as it was developed pre 1935 way before any German FF33 would have been known in Sweden. It seems to me to be a logical enhancement from the former m/26.

The case first was planned to be made of glued together masonite panels, in the 1939 catalog it is already listed as a bakelite made case. Originally the device used the 3V B3a battery (Ericsson product IDs BKA1101/2101), later an adapter allowed the use of standard IEC R20 (D-Cell) batteries.

The external dial module exists in 2 versions, a round one and a square one, I got a square one which I believe is the newer version.

Description from the 1939 Ericsson catalog:

[...] The appliance is built into a box of bakelite and is equipped with an adjustable leather carrying strap. The lid is held in place by two snap locks placed on the short sides. The snap locks are opened by depressing the fittings on the top of the lid. The device has a strong inductor and a sensitive polarized AC clock, which together with other details are mounted on a stand of strong brass plate and form a unit, the insert, which is screwed into the box. The bakelite handset is equipped with a replaceable headphone and microphone capsule, a key for closing the microphone current and a rubber hose cord. [...] The lid has a hole, which is covered by a rubber cover, whereby the telegraph key can also be actuated when the lid is closed. [...]

Unique feature
Hook cradle activated when switching to CB mode.

Datasheet
Size: 260x86x187 mm
Weight: 4.2 kg
Material: Bakelite cover, light-alloy body
Battery: 2x 1,5V D-Cell
Magneto (removable crank), Ringer (1kOhm), Buzzer
Pluggable Bakelite Handset with P.T.T. button, Pluggable Headset
Included screwdriver
Optional external rotary Dial

Visit http://fieldphones.org/episode44/ for additional information.