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Old 2nd Feb 2019, 4:08 pm   #1
Mach One
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Default Philips 341A Valve Radio

I have long had what could potentially be described as an enduring attraction to the Philips 341A valve set ever since a friend of mine leant me one in the mid-Seventies. Hardly the most remarkable or rare set but I find its bakelite cabinet shape really attractive. After this, Philips radios seem to me to revert to a more mundane box-like character. Interestingly, I had its relative - the 353A which boasted the new-fangled VHF band instead of SW - at around that time, too, and although that used the same case style, the electronics within it - particularly in the audio output section - meant that it never seemed to sound as good or perform as well.

I've been collecting bits for the occasion of a 341A restoration for years. After several purchases of models which were in less than ideal condition I was finally given one which made it worthwhile by a friend (serial number PH94558, so I guess relatively late). For a while I just didn't quite have the courage or - more to the point - time and space to get down to it. But, armed with the encouragement and experience of two other recent Philips radio set restorations, I have finally managed it.

I initially powered it up to see if it worked (outside, in the back garden, in the summer...). I had previously attempted to replace the main HT smoothing capacitors, very generously valued at 50uF each by re-using the case of the original metal-clad Dubilier and putting a pair of modern equivalent capacitors inside. I found opening the case of this capacitor extremely difficult and, although I did ultimately manage to get the innards out, I could not find a good way of fitting the new ones inside the case and to the original tag section of that capacitor. In the end, I gave up and manufactured a rather inferior-looking solution with unclad stripboard and an old-fashioned solder tag arrangement. Not pretty, but there you go!

Then I set about checking the values of the resistors and ording up replacements where necessary and also replacements for the old "waxy" capacitors. Obtaining these in the correct values was much more difficult that I expected. I have recently settled on the 1000v polypropylene capacitors as my preferred type due to their similar shape and size to the originals. You can see the end result and a similar unmodified (532A) chassis in the attached pictures to compare the result. To make the correct values, and not being able to obtain every value that there might be, I ended up often putting capacitors in parallel. Once again, not pretty...

A few of the resistors, as expected, were enough off-beam to be replaced and a couple in particular produced for me a puzzle. One was the high-stability resistor R15 (120k) which was enormous - almost two inches long! Quite why, I do not know. The power dissipated would not be a lot as far as I can tell. The other one was something that I have also seen in the other similar chassis which I have where R8 (ostensibly 56k) feeding one of the grids of V2 has been installed as two 47k resistors in parallel (23.5k). Quite a difference. Pssibly, as a result, the voltage measured at the valves is 77v instead of the expected 54v. There is no mention of this change in any manuals that I have so far read. I did wonder about changing it back to 33k...

With all the components checked or replaced it was time to turn on the set. Thankfully, I seem to have re-wired it all correctly and it worked. I cleaned the chassis with a toothbrush and vacuum cleaner, cleaned the case, knobs and scale and put it all back together. It's not a high-class refurbishment but I'm happy if it looks original, clean and works. You can see the end result in the last two pictures.
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Old 3rd Feb 2019, 8:28 pm   #2
Wellington
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Thumbs up Re: Philips 341A Valve Radio

Good work on getting this going. Sounds like it was a bit of a struggle what with the smoothing caps and having to pair-up the other caps to get the right values. Still, as you say, "it looks original, clean and works".

I have one of these somewhere in the depths of the attic. I seem to remember that it was one of the first valve radios I bought from the local saleroom, back in the 80s. I was particularly impressed that it worked without needing anything doing to it, and it had a very nice sound (which was probably due to the typically complex Philips feedback arrangement a nice description of which I have included below (from the Philips service manual)).

Of course, if I knew then what I know now, I would've been a lot less happy about running it without at least carrying out a few checks. I think it survived, though. I don't remember it stopping working!

Howard did a nice restoration of one of these a few years ago. Interestingly, he also had a few issues with capacitor values.
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Old 3rd Feb 2019, 9:59 pm   #3
paulsherwin
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Default Re: Philips 341A Valve Radio

These are nice old sets. My grandad used to listen to the football pools results every Saturday on one when I was little. I do have one, though the speaker fabric has proven difficult to clean. I still need a good one.
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Old 5th Feb 2019, 5:40 pm   #4
Mach One
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Default Re: Philips 341A Valve Radio

I have had a go at cleaning the speaker fabric on one that I was attempting to smarten up a few years ago and agree - I don't think my ministrations improved things.

Having bolted everything together and checked it out, this one does not sound as deep as my memory of these units. I will have the check that I have correctly replaced and connected all the components around the audio feedback loop.

Howard has always been the Gold Standard to aim for in these matters. Sadly, I can only dream of approaching that.
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Old 5th Feb 2019, 6:39 pm   #5
paulsherwin
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Default Re: Philips 341A Valve Radio

Mine sounds OK given the bakelite case and modest size. The chassis is actually a standard Philips design, used in most of their early 50s models with minor variations.
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