mende: 242W (242 W);

ID: 218760
? mende: 242W (242 W);  
18.Apr.10 03:11
133

Wyatt CIRCO (USA)
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Wyatt CIRCO

 Hello, Im an american collector and I just got a Mende model 242W. Can anyone tell me how to align the radio? I cant read German so the Manual doesnt help.

Thanks,

Wyatt

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Translation of Mende 242 Alignment Instructions 
30.Apr.10 09:36
133 from 2758

Thomas Albrecht (USA)
Officer
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Thomas Albrecht

Hi Wyatt,

Here's a translation of Section 5 "Abgleichung" (which is the alignment instructions) from the available pages of schematics/literature for this model:

5.  Alignment

a)  Intermediate frequency:

  • Set an RF generator to the "IF" setting
  • 468 kHz normal, 473 kHz for western Germany, 482 kHz for Schlesien (northern Germany)
  • Connect the RF generator output to the control grid of the AK2 tube.  Ground this grid with a 50 K resistor.  Set the tuning dial to 200 m.  Align the 4 IF transformer inductors in the following order:  2nd IF, 1st IF for maximum level on the test detector instrument.

b)  For alignment of the IF notch filter, connect the RF generator to the antenna terminal.  Adjust the notch filter for minimum ouput.

c)  Shortwave:  Adjust the trimmers at 20 meters and the inductors at 50 meters for maximum ouptut.

d)  Medium wave:  Adjust the trimmers at 225 meters and the inductors at 530 meters for maximum output.

e)  Long wave:  Adjust the trimmers at 1300 meters and the inductors at 1800 meters for maximum output.

Comments:

  • They seem to be calling for some specific kind of instrument for measuring the output.  You can simply use the AVC voltage (more negative voltage means "more output").  The AVC voltage in this radio can be measured across the "50000pF" (0.05 uF) capacitor connected from ground to the second IF transformer.  Or you can listen for maximum volume if you use modulated RF.
  • They also seem to have a specific RF generator in mind.  Don't worry about the instruction to set it on "IF."
  • No need to worry about the various IF frequencies they are suggesting.  Just use 468 kHz.  The other frequencies must have been chosen to minimize some kind of interference in the regions they mention.
  • The locations of the various adjustments are shown on the page with "Abgleich Vorschrift" at the top.  The diagram is the top view of the chassis.  The 1st IF transformer is labeled as "I. Bandfilter"; the 2nd IF transformer is "II. Bandfilter"; the notch filter is the "Leitkreis"; the RF front end tuned circuits are in the "Vorkreis" box; and the oscillator adjustments are in the "Oszill." box.  Note that you have two trimmers and two inductors to adjust (one each for the RF and oscillator) for each band. 
  • For adjustments c), d), and e) above, the RF generator is connected to the antenna terminal and ground.
  • To convert from "meters" to frequency, use the formula f = 300,000 / wavelength.  For example, 530 m = 566 kHz.
  • The oscillator adjustments will have the effect of adjusting the dial calibration (they will "move" stations up and down the dial).  The RF front end adjustments affect sensitivity.

Good luck,

Tom

P.S.:  I am not positive I understand the "Leitkreis" correctly.  Others are welcome to provide correction if this is something other than an IF notch filter.

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Translation... 
01.May.10 06:02
156 from 2758

Wyatt CIRCO (USA)
Articles: 14
Count of Thanks: 4
Wyatt CIRCO

Thanks a bunch Tom. The radio plays beautifully!

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This thread was moved back manually because it received a valid answer. 

Moved from board »* TALK - visible for members only« on 01.May.10 06:38 from Thomas Albrecht