grundig: 2440U (2440 U);

I have a FM problem with a Grundig 2440 and 2520. Both use the AM section for FM. Both radios work fine on AM/SW but are dead on FM, not even air noise. Is this a common problem and were can I look to fix it. Thank you Leo

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Hi Leo,

Since the AM/SW sections are all working, the possible culprits would seem to be the FM discriminator, the switching arrangements (dirty contacts) or the FM Tuner (ECC85).

If you have an FM Signal generator, you could remove the ECC85 and inject an FM modulated signal 10.7 MHz at the grid of the ECH81. If all seems well then its not the discriminator. (EABC80). If you don't have an FM signal generator, sometimes putting an aerial on the grid will send shortwave stations on 10.7 MHz through the system. (This is not a great way to do things though - might be better to knock up a makeshift sig gen.)

Next, you could try replacing the ECC85 and tuning the radio to 90MHz. Using another radio tune to 100.7 MHz to see if the FM local oscillator is behaving. (Assuming LO is on high side). Or tune to 100.7MHz and Listen for the LO on 90MHz.

Check the tuner for broken feedthrough caps and wires missing. Check the ECC85 (or substitute a known good one). If the discriminator doesn't work, try substituting the EABC80. Check voltages and caps in the tuner.

Those are the simple things. Hope you come right. - Bryce

 

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