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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only.

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Old 2nd Mar 2004, 4:48 pm   #1
Sideband
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Join Date: Oct 2003
Location: Croydon, Surrey, UK.
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Default Philips B3G63A. Intermittent FM volume.

I've been involved in restoring one of these for a colleague at work. He actually bought two from Ebay (both wrecks!!) but he didn't know any better. He just thought they looked good.

Anyway one of the sets was electrically complete and the other was minus drive cords (all four)! However the one without drive cords was the most viable to recover. Having done all the work, I was left with intermittent operation on VHF.

I spent ages trying to find it and was convinced it was in the FM discriminator. When the fault was present it was very low volume and distorted, and the last IF would not tune properly. I was on the point of swapping the IF transformer with one from the other set. I was examining the wiring to decide what sort of job it would be - very close wiring and short leads - when I noticed one capacitor had very long "tails" to its leads and one of these tails was touching an adjacent unused tag on the IF transformer. A swift application of a screwdriver blade and a pair of cutters removed the offending tail, and the set then worked. I was able to tune the discriminator as per the service sheet.

I was left with a small amount of distortion that was present at all levels. I noticed that even at minimum volume there was a small amount of distorted sound. I decided to change the EABC80 and it completely cured the problem. The new valve gave a much cleaner sound and a final readjustment to the discriminator made the tuning much smoother.

I've had this a couple of times with EABC80s used in Philips sets so it's worth trying one even if the gain seems to be good.

Rich.

Last edited by Paul Stenning; 27th Dec 2004 at 12:39 pm. Reason: Fix link or code for vBulletin
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