blaupunkt: 7.631.640 ab 2300001; Frankfurt

I have a Blaupunkt car radio above & I was interested to know how to expand the FM to recieve 104MHz as it should. Currently it will only recieve up to 102.9MHz. 

 The original FM band width was 87-104MHZ. If in recieving up to 104MHZ the radio looses some of the lower band width I'm OK with that.

Many Thanks in advance.

Terry

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If you look up the first schematic, you can see the FM Tuner at top left corner.
Transistor V50 is the RF stage, V51 the Mixer, and V52 the oscillator. Its circuit consists of:
- L52 for tuning,
- C74 is the basic fixed capacity,
- C75 is the trimmer to adjust the frequency range,
- and D50 is a varicap diode for AFC.

You may shift the range by carefully adjusting the trimmer C75. I think both antenna circuit and intermediate circuit are rather wide. There are no means for fine adjustment (and no need if the band shift doesn't go too far off).

As far as I can see from PC board picture (lay2), C75 is found on P2, component side, bottom left half.

That should enable you to find the physical location.

Good luck!
KoBi

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