Philips Repro Superinductance R634/15.

[Joe]

This is my latest:-

                   

It works OK, and even the switches aren't too dirty.

Despite the wooden (MDF actually) case it still sounds like a transistor. That said there's plenty of room in the case and I'm not short of EL84s...

- Joe

[tiv48]

hi JOE
did you make that case?
if so the wow.
rob t

[Joe]

No, I'm afraid not. I bought the set in an auction last Friday and collected it this morning.

- Joe

[Refugee]

The donor for the PCB looks early 1970s.

[Yorkie]

A good find Joe - it looks in quite good shape, and a much more sensible size than the monstrous original!

As I recall, these repro sets were marketed by Philips in 1983 (ish) to commemorate the 50th birthday of the 634 'Superinductance' TRF set (what later became known as the 'Ovaltiny' because it featured in an Ovaltine advert), the DC version of which went into production in 1932/3. An AC version followed in 1943. A large ungainly set, albeit much sought after by some. It was veneered with indifferent nondescript veneer, and 'faked up' with two bands of toner, as in Joe's repro set, to make it look like two bands of contrasting veneer.

As with all sets of the day, it was sprayed with cellulose lacquer, which flakes off, so amateur restorers who think they can 'restore' the cabinet get to work with Nitromors, only to find to their horror, that the toner (which doesn't soak into the veneer but sits on it), that they thought was bands of darker veneer, comes off, along with the lacquer. They then cut their losses and give it a few coats of Danish oil, doing irreparable damage as Danish oil doesn't simply dry - it goes through a chemical change and 'cures'. Once applied, it can never be removed.

Really, from the outset the veneer on these cabinets was of such poor quality that even in the hands of a professional, it would be pretty much a lost cause, trying to make what was a sow’s ear into a silk purse. Almost all of the Superinductance sets I've seen have been got at in this way. If you look at the example at the link below, you will note the following statement:

"The cabinet has been re-polished sympathetically and the set has been overhauled"...

(I suppose it depends upon one’s definition of ‘sympathetic’ but to destroy the original finish and replace it with an entirely different finish, destroying original features would not come within my understanding of ‘sympathy’). Any radio belongs to the person who owns it at the time, and it’s there’s to do with what they want, but to be blunt about it, with 'classic' radios - rather than just any old radio - if the owner for the time being doesn’t have the skills to do the work properly, why not entrust it to a professional, rather than make irreversible changes? I actually find this set offensive to the eye:

See: http://www.thevalvepage.com/radios/phili...a/634a.htm

Another example states:

"The famous 'Ovaltiney' model 634A, one of the 1932 Superinductance range. This is a very good clean example, which has had a thorough restoration and works well. It has lost the bands of stain round the top and sides, but the front has exceptionally nice veneers. original cloth, back etc".

It hasn’t ‘lost’ its banding - knobs and backs, and DAC90A mains leads get ‘lost’. The banding has been deliberately removed during a botched ‘restoration’ process at some time during its life.

See: http://www.vintageradio.co.uk/htm/sales4.htm

Pedantically postulated Yorkie.

[Radio Fixer]

Good to be pedantic David but you are not correct on the facts about the 634A which was from 1933 and an AC only set. Models with an A suffix are AC and models with a C are DC, not listed for the 634. My 834C has an A model as well. (Source RR)

1947 was way out, SI sets were all over by 1936.

Here's an extract from an article I wrote on the restoration of an 538A from 1934

"The later and more expensive Super Inductance TRF set had four coils on glass formers in big copper cans. Each section of the tuning gang needed to be screened, and a potentiometer was coupled to it to make for a reasonably constant gain across the bands. The chassis was divided into sections with switch wafers having their own compartment. There is extensive use of screened wiring. The Superhet radio could have coils on cheap cardboard formers in small aluminium cans. Its tuning gangs could be un-screened with no coupled potentiometer as the IF strip was essentially of constant gain (but modified by AVC action of course). Compartments were dispensed with and the switch wafers used only a piece of metal between them (performance sets) or nothing at all. Naturally Philips covered themselves and were making a Superhet, the model 588, in 1934 whilst at the same time continuing with the Super Inductance sets. But economics spelt the end of these,wonderful as they are, and by 1936 there were no new models."

The 634A is a big set as it uses the largest copper cans for the SI coils. My French 538A (472 equiv.) has the same coil layout (additional tuned bandpass filter) as the 634A but to make it in a smaller cabinet the screening cans are smaller and so possibly lower Q and maybe slightly less performance. Even so it is a masterpiece of radio engineering for the time with fantastic attention to detail and component quality. Not a single resistor was out of spec! The coils also never give problems. As to performance its marvellous to put a Wobb on it and measure the bandwidth as the set is tuned from one end to the other. Its almost constant at around 6kHz half height, a fantastic achievement that other TRF sets never came near. In performance its better than all Superhets I have tried, from the around same period, without a tuned RF stage.

As to cabinets well often plain veneer was used around the tops of curved cathedrals, Philco did that as well. Maybe its more appropriate than some grained veneer and you certainly wouldn't want to splice in pieces at the bottom. Putting back the original band of toner at the bottom is easy anyway. Philips did some nice veneer on fronts and square sets. The 838A has a beautiful mix.

As to Joes' repro all I can say is UGH! I just loath them but each to his own and if he can like it that's fine. Give me a genuine SI to work on, they really are fascinating and great performers. A friend said "Philips never made a bad radio" and I would go with that.

Gary

[Yorkie]

Thanks for the update Gary - most interesting.

My knowledge of them is very sketchy - I've never liked them - far too large and ungainly for my liking, and most that I've seen have been got at by the 'bodgertronics brigade' - more than once I guess! Sets of that era beg the question of should the be 'conserved' or restored, but that's a topic that tends to generate more heat than light.

We visit many National Trust houses, and although the NT make a big thing about sympathetic 'conservation' of buildings and their contents, they almost always have vinitage radio sets on display which have had all their innards ripped out and an MP3 player inside pumping out music. Dire, but someone in vintage radio circles will obviously do the bidding of the NT and supply what they ask for. (Haven't yet come across an 'Ovaltiny' that's had this treatment, but then most have already been vandalised in one way or another. I guess the NT probably think it's safer to treat radios like this rather than use restored ones that don't, and can't comply with current standards in some respects, which they wouldn't like to leave switched on an unattended all day long.

[pwdrive]

Some of these old TRF sets were excellent performers, many military versions were used throughout WW2, the American and the German ones in particular were a masterpiece of TRF engineering, check out the Torn Eb etc. Lo radiation was a concern with some superhets as they could be DF'd by the enemy, with the TRF the regen in oscllation for CW work was well down the signal processing chain, I think the Germans got their regen osc radiation at the antenna teminals down to around 10 uv on some sets.

Lawrence. Edit: Also check out the Lo6K39a receiver, 6 tuned circuits...

[pwdrive]

The constant gain system you describe Gary is interesting, those early radio receiver designers were no fools, another trick was to use a high impedance primary designed to broadly resonate just outside the lower end of the band being tuned.

Lawrence.

[Radio Fixer]

They are not a set for the faint hearted but if you like a challenge and are prepared to spend the time (and have the skill with soldering irons and hand tools) then they are very satisfying to restore. This one only had minor work from a previous restorer. All the wax caps were taken out, and many other items as well (new vol control fitted), and restuffed but it went back together as neat as could be. For BVWS member then there is more in Winter 2011.

I wouldn't call this one ungainly and the most beautiful of all (big Yes!), and the most expensive, is the 636A, with a plain blonde veneered front.

   
   
   

Those really are bike spokes going from corner to corner for bracing. That's Philips for you and why I love them so much. There are so many clever things in these sets, like the liner tuning dials and the shaped 'jewel' like tuning gangs, the gain levelling, the removable station names dial and the method of aligning it to the wave lengths. The accuracy of the dial markings and the adjustments to allow this ... They are often odd but amongst the most interesting of radios to work on.

Oh! and note the permanent magnet speaker and an included mains filter!

Gary