21-05-2013, 07:29 AM
(This post was last modified: 21-05-2013, 07:55 AM by 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
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
