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IF transformer Alignment

Geschreven door PANDU RAJAN op 27. Maa 2005 19:08:55:

Dear Friends

Can Somebody give me Explanation to this problem.

I am in the process of restoring a Philips India radio set B6CA77A. It is a 5 band radio set with the following valves: EF89,ECH81,EBF89,ECC83,EL84,EZ81 & EM80.
As per Philips Recommendation the IFS are tuned as follows
1. Gang Condenser at Min position
2. Vol control at Max
3. 452KHz Signal is applied through a signal generator to pin 2 of ECH81 through a condenser of 33000PF and the 4 IF cores are trimmed as per the sequence given in the service manual. For a particular setting of the signal generator I get a max d.c. voltage of 5 Volt at the terminal of the 2nd IF transformer which finally goes to the volume control. The other terminal goes to the detector diode in EBF89.The problem is keeping every thing same now if I change the band switch selection from MW to SW1 or SW2 or SW3 or SW4 then this voltage changes. If it is in SW1 then the voltage increases to 8 Volt. In SW2 this voltage becomes 6.5 volt.My Question is Why this voltage increases? Can Somebody give answer to my Problem?

Regards

P.RAJAN




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