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====== E-641: Telefunken E 148 Uk/2 ======
**E-641**, **Telefunken E 148 Uk/2**; developed and produced by [[Telefunken D|Telefunken, Ulm]].

The VHF receiver [[Telefunken d|Telefunken E 148 Uk/2]] had the designation E-641 in the Swiss Army, six sets were purchased for the "Funkpolizei" (military radio surveillance).

{{:images:e-641-telefunken-e148uk.jpg?direct&600|E-641 / Telefunken E148 Uk/1}}
===== Technical Data =====
  * [[Principle]]: [[Single conversion]], [[IF]] 10,7 MHz
  * [[Modes]]: [[A1|CW (A1)]], [[A3|AM (A3)]], [[F3|FM (F3)]]
  * [[Frequency range]]:  20 - 80 MHz
  * **Analog dial**, accuracy 25 - 50 kHz
  * [[Sensitivity]]: [[CW]] < 0.2 μV / [[Selectivity]] -3/-60 dB: 25/100 kHz

==== Power Supply ====
  * [[Mains]]: 110 - 240 V AC

==== Dimensions ====
  *  550 x 202 x 384 mm, 40 kg

==== Accessories ====

{{:images:e-641-telefunken-e148uk-front.jpg?direct&600|E-641 / Telefunken E148 UK/1}}
===== Operation =====
The Telefunken E 148 Uk/2, which was used in the Swiss Army under the designation E-641, was developed around 1957 and acquired in 1960, six receivers have been purchased for use of the "Funkpolizei" and another six sets to be used in the VHF direction finding system [[P-721]].

The 16 tubes single conversion superhet consists of a tuner insert (RF unit), with the frequency determining parts and the E 148/149 basic unit, in which the IF 10.7 MHz is processed.

In the middle of the front panel, the frequency-determining insertion is located. In case of the E 148 this is the 25 - 84 MHz unit. With the switch "1.Oszillator" the set can be set to crystal controlled fixed frequency reception or VFO operation, in the frequency dial window, the reception frequency is displayed with an accuracy of at least 50 kHz.

The mode selector switch is located on the left of the front panel; in the positions "A1 / A3 Hand", the RF gain can be set manually. At the top is the switch for the low-pass filter.

On the right you will find the volume control (AF control), which is combined with the power switch, the switch to set the measuring instrument to indicate the RF or AF line level and below the monitor speaker.

===== Technical Principle =====
{{:images:e-641-telefunken-e148uk-block.jpg?direct&600|Blockschaltbild Telefunken E148 UK/1}}\\ 
In the E-641, the tuning unit 25 - 84 MHz is used, the entire frequency range is covered in one band.

After two tuned HF preamplifier stages ([[de:E180F]], [[de:EF80]]), the signal is converted to the intermediate frequency of 10.7 MHz in the mixer [[de:E88CC]]. The oscillator signal can either be derived from the tunable VFO ([[de:EF80]]), a quartz oscillator (operating frequency + 10.7 MHz) or an external high stability oscillator.

In the basic unit, the IF of 10.7 MHz is amplified in six stages (all [[de:EF80]]), the IF bandwidth is +/- 12.5 kHz.

After this, the signal is forwarded for demodulation, in AM (A3) mode, a semiconductor diode is used, for [[CW]] reception (A1) a BFO ([[de:E88CC]]) is switched on, in the FM (F3) demodulator one [[de:E88CC]] each works in the limiter and discriminator stage.

A further [[de:E88CC]] is used in the AGC amplifier and in the AF output stage, in addition to the speaker there are connections for the headphones, an 10.7 MHz IF output and a broadband IF output to connect the panoramic display PaG148 directly.

The set operates on mains voltages of 110 - 240 V, which are stabilized ([[de:STV150/30]]). 

==== Valve setup ====
V1 ([[de:E180F]], RF preamplifier); V2 ([[de:EF80]], RF preamplifier); V3 ([[de:E88CC]], mixer stage); V4 ([[de:EF80]], oscillator); V5 - V10 (six [[de:EF80]], 1st - 6th IF amplifier stage); Gl.diode (semiconductor diode, demodulation); V11 ([[de:E88CC]], BFO); V12 ([[de:E88CC]], FM Limiter); V13 ([[de:E88CC]], FM discriminator); V14 ([[de:E88CC]], AGC amplifier); V15 ([[de:E88CC]], AF output stage).

==== Development ====

==== Field use ====
The Telefunken E 148 Uk/2, which was used in the Swiss Army under the designation E-641, was developed in around 1957 and acquired in 1960; six receivers were used as independent receivers for the "Funkpolizei" and another six to be used in the VHF direction finding system [[P-721]] 

{{gallery>:images?e-641*.jpg&0&80x80&lightbox&showtitle&titlesort}}

==== Manuals ====
  * {{ :manuals:e-641-telefunken-e149-uk1.pdf | Ultrakurzwellenempfänger E148 Uk/1}}

==== Additional information ====
  * [[http://armyradio.ch/radio-d/e-641.htm|E-641 / E148 Uk/2 auf www.armyradio.ch]]
  * [[https://www.radiomuseum.org/r/telefunken_ultrakurzwellen_empfaeng_2.html|E-641 / E148 Uk/2 auf der Website von www.radiomuseum.org]]