Philips 353A

[Sideband]

This Philips seven valve AM/FM radio came to me by way of someone having a clear out. I must admit that when I first saw it, I was not impressed by it’s styling it being a fairly typical 50’s set. However I was interested in getting it working even if only to pass it on to someone else. It was partly working on AM at least although the sound was rather muffled and sensitivity was down. FM was terrible and could not be tuned in without considerable distortion.

Removal of the back revealed dusty innards with the main chassis at the bottom and the FM part vertically at the left. The rectifier valve was mounted horizontally over the top of the mains transformer…typical of many Philips designs. When the bottom panel was removed to reveal the underside of the chassis, there were the usual large black pitch-covered Philips capacitors. These go much the same way as Hunts capacitors and would probably mostly be leaky. The audio coupling (That Capacitor), had been changed for a Mullard ‘mustard’ type and would probably be OK.

First thing was a good clean up and then set about changing the black pitch capacitors. These all measured wrong on the bridge and most were very lossy. Some wouldn’t ‘null’ at all. I used Mullard ‘mustards’ for the replacements which fitted in very well and did not look out of place. Second test showed that AM was now very good with excellent sensitivity. The audio quality had been transformed and there was a very good bass response, helped, no doubt by the generous negative feedback applied to the output stage. FM was still dreadful though and very distorted.

This set uses two EF80 valves in the FM tuner, one used as RF amp and the other used as a mixer/oscillator. It seemed unlikely that these would be the cause of distortion so I tried the EABC80 discriminator/AF amp which made absolutely no difference so I put the old one back. Voltage checks didn’t reveal anything either. Peering underneath again, I then spied a 5uF 100v hiding under a tag strip. This is part of the discriminator circuit and snipping one end and measuring on a meter showed that it was behaving like a 3k resistor! I fitted a 4.7uF at 160v as a replacement and tried again. FM was now working perfectly and each station could be tuned in correctly without distortion. Audio quality was superb with plenty of ‘top’ and the bass response was also excellent. Performance testing now showed the set to be very good indeed. It even manages to tune classic FM (on 102.2 in the London area) and I’ve just listened to the whole of Dvorak’s New World symphony which showed that the audio stage can give a very good account of itself.

Finally I tackled the Bakelite cabinet. This was slightly dull and had the inevitable paint spots (brown this time). I rubbed it down (not too hard) with 000 grade wire wool slightly dampened, then after drying thoroughly, applied a coat of beeswax floor polish rubbed in with fresh 000 wire wool (again not too hard) then buffing with a soft dry cloth and then applied several more coats with a soft dry cloth, buffing well between each coat. That restored the sheen and the set now looks very good.

My conclusion is that looks can be deceptive. It’s still not a favorite of mine from the styling point-of view but it’s growing on me! However performance is superb and it will certainly stay as part of the collection. Previous experience with FM tuners that use 2 EF80’s has not been good and another set I have struggles at 100MHz even with new valves. I think the EF80 is struggling at these frequencies as it was normally used as a TV I.F amp at about 45MHz. However good design and layout obviously plays a major part at these higher frequencies in this Philips set.

[Tim]

Good resto Richard.
I think you were lucky with the HT caps, I have seen a few of these over the past 20 years or so, and all had duff smoothers.

[Sideband]

Interesting point raised there Tim. I noticed there was a 100Hz hum from it that I fancied had got a little louder. Maybe it's a sign of imminant failure. I've got a couple of new 47uF caps that will fit nicely within the original can. Maybe a job for the weekend!


Rich.

[johnn]

I restored a B3G63A with the same chassis except for the row of push buttons & it too works well. It's shown in the BBC "Miss Marple..Nemesis" programme. Absolutely correct for the time! Incidentally, well done Richard.
John.

[paulsherwin]

Subbing a pair of EF184s for the EF80s may improve performance, as these valves are a later design with better HF performance. The pinout is the same.

Paul