Freiburg 12 - variometer cores.

      Freiburg 12 - variometer cores.

      Hello, does anybody have a measurements of how the cores should be positioned on glass rod? Unfortunately during cleaning glue suddenly let go and the cores slid upwards. First time it happened, and of course with 87-104MHz thus I cannot compare with other Freiburg.
      I only found the topic with measurements of Konigsfeld variometer, which are shorter.

      Regards
      Piotr

      Hi Piotr,

      if no one messed up the FM frontend and the trimcapacitors are still in their original positions, it´s no probblem at all.
      You can use the SABA instrucions for an alignment of the HF-section (see below).

      1. Clean the cores and the glasstick. Make sure the cores can be easily turned on the threds of their inner small tubes.

      2. You have to start with Position 1b) and adjust the cores of L105 and L104 at 100 MHz by gently moving them on the glasstick with a toothpick or similar (no metal!).

      3. Then you can fixate the cores carefully at the right positions with a 2-component glue and make the final adjustments of L105 and L104 afterwards by rotating the cores (1b). Then C106 and C111 can be adjusted at 90 MHz (1a).

      4. You repeat 1a -> 1b several times until there are no more improvements to be made. You now must fix the the threads with a small amount of lacquer or paint.

      5. Align L102 at 95 MHz (2) first by moving the core with a toothpick (coarse), then by turning it when it´s glued to the glasstick (fine). (Dont forget the fixation with lacquer / paint when you are done.)

      6. You finally adjust C104 for best Neutralisation of of the oscillator signal (3a -3c).

      Done.
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      Thank for the answer, I hope UKW tuner is not touched but I can't be sure - unfortunately someone was "repairing" this radio and there are so many things messed up... Wrong capacitors, a few of wrong resistors (additionaly he ddin't replace those brown carbon resistors), unadjusted cogs on motor and what's worse - he apparently decoupled automatic filter. I don't know if he didn't move those cores - I cleaned so many variometers and never once core did move and here they just slid. Luckily I bought it quite cheaply as radio was almost non functional.

      So I'm gonna start by comparing general position of the cores with variometer from Freiburg 11, then I have to tune it carefully.
      I suppose it will work with radio stations? In my area there are two senders at 99,7MHz, and 89,8MHz. Unfortunately my HF generator ends at 30MHz.

      Also I spent two hours cleaning the chassis from ugly silver paint:

      0nfTn-VOm9Yq.jpg


      Regards
      Piotr

      Hello again,
      as it turned out it worked great! Voltage on ratioelko is around 19V on strong stations and there's much more of them.
      After replacing some caps and old resistors amp works great.
      But unfortunately automatic filter was badly decoupled, apparently someone turned it so tightly that I was afraid of breaking everything. Luckily it moved eventually. Somebody was guessing that it must be filter, but there was a problem of short circuit on automatic on/off switch - part of the engine voltage was on R726 (braking resistor for slow search) so the engine always slowly turned in one direction.

      So is there a nice way of setting coupling between coils? How should one manage to do that? Usually in my all automatics there was only need of slight adjustment, but here...


      Piotr