Telefunken E 127 Kw/4
Telefunken, Ulm

Swiss Army Communication Sets
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Exxx Designations
E-600 / Autophon E39
E-601 / Zellweger E41
E-602 / Autophon E44
E-603 / Autophon E45
E-604 / Autophon E46
E-606 / Velectra
E-627 / Autophon
E-628 / Autophon
E-629 / Collins 51J-4
E-640 / Telefunken E127
E-643 / Collins 51S-1
E-645 / Siemens E311
E-646 / Zellweger
E-649 / Watkins-J.
E-655 / Racal
E-657 / Telefunken
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überarbeitet am 21.4.2012

In the Swiss Army, the Shortwave receiver Telefunken E 127 Kw/4 "Rainbow" carried the designation E-640. It was mainly used as surveillance receiver. In contrast to Germany, where the variant Kw/5 with a frontpanel impact protection grid and connectors on the front was in use, Switzerland used the commercial model Kw/4 with most connectors on the rear face.

Single conversion, I.F. 525 kHz

linear Analog dial

AM, CW / SSB (with BFO)

CW < 0,2 uV

Selectivity -6 dB
12 / 6 / 3 / 1 / 0,2 kHz

RF-Gain, AGC

The E 127 Kw/4 has been produced in the mid-fifties until the mid-sixties in different variants and has mainly been used by official agencies, for weather reports, press communication and as monitoring and surveillance receiver.
The Swiss Army used the commercial variant E 127 Kw/4 painted in grey with connectors on the rear face.

The receiver's dimensions are 550 x 375 x 390 mm and it's weight 44 kg, it is a bit more compact compared with the E-104 or the Rohde & Schwarz EK-07. The receiver can be powered from 110 - 240 V mains and has a power consumption of 70 W with it's eight tubes.

In the middle of the frontpanel, You find the multi - colour semicircular frequency dial, the band segments are colour coded: the 1,5-3,3 MHz range 1 in white, range 2 from 3,2-7,1 MHz in yellow, range 3 from 6,9-14,1 in grey, range 4 from 13,9-22,1 MHz in green and the last range from 21,9-30,1 MHz in red.
At the left of the "Rainbow dial", You find the switchable monitor speaker and at the right the measuring instrument, which can be set to display signal strength or the AF level, as well as the BFO for CW / A1 reception.
The other controls are located in one row below the frequency dial: from the left the bandwidth selector, the main tuning knob (with fast tuning mode when pulled out), the band selector with the identical coloured marks, the RF gain control and the AF gain / volume control.
Below at the bottom of the receiver's front panel, You find some headphones jacks on both sides, and the switches for the noise limiter, the automatic gain control (automatic stands for AGC) and the modes switch, which activates the BFO for CW / A1 morse code reception.

As options, the receiver E 127 can be connected to the radioteletype adaptor TgFs 127 (reception modes F1, F3), the single sideband demodulator BP 102 for SSB reception with full (A3a) or reduced carrier (A3b) and the diversity adaptor Abl 305.

And now a short luck qat the receiver's block diagram:
The antenna signal is fed via two R.F. amplifier stages (EF85) to the first mixer(ECH81), where the intermediate frequency of 525 kHz is generated. The i.f. signal has to pass two crystal filter stages (EF85) with selectable i.f. bandwidth and will be demodulated (ECH81). For CW reception, the signal of the BFO is added. The audio signal is amplified in the audio final stage (EL84). E-640 / Telefunken E127 kw/4 Blockschaltbild

The E-640 / Telefunken E127 has been in use as surveillance receiver, some of the sets seem to habe been modified to crystal controlled fixed channel operation.

© Martin Boesch 21.4.2012