28-09-2015, 06:27 PM
The Radio Museum link to the pictures of the set will, I think, answer at least some of your questions, on which I'd comment as follows:
1) Yes, it will have had a back, and there's a pic of the top LH of the back at RMORG, but unfortunately, not the whole back. Sets of this era generated a lot of heat, and I believe it was commonplace in less safety conscious days to remove the backs of sets to allow more ventilation. To be able to faithfully replicate the back panel, what you really need is a 'brass rubbing' of a genuine one. By that, I mean not a drawing or a picture, but a piece of paper held against the back of the set then a wax crayon rubbed over all of the ventilation slots and other openings (for the mains flex etc) to accurately show the size, location and shape of the holes. Also, a pic of the back to show any labels such as valve types, operating voltages, make and model No. I've made quite a lot of replica backs for a range of radios in my collection using a router jig I designed for that purpose. The hardest part has always been getting good information about the size and shape of any openings, and the label size, text, font, colouring etc.
2) The set was introduced in 1933, and it's my guess that the paper-boxed electrolytic is a wartime replacement in the early 1940s when the set was around ten years old. A lot of appallingly bogged repairs were carried out during that era - sometimes by inexperienced apprentices too young to be drafted into the armed services, or older guys who were too old or too unfit for active service. Clearly anyone who was experienced and skilled in radio repairs would have found themselves called up in very short order! Typically, these replacement caps were just bodged in and left dangling on the wires wherever space could be found for them. I've attached a pic of one I found in an Ekco set I'm restoring (slowly!). It was just dangling under the chassis, the wires having been twisted together (not soldered), and wrapped in insulating tape. (You'll see the tape on the yellow wire in the attached pic).
3) The brackets look the same at each end on the RMORG pictures.
The thing that would worry me most about the set is whether the speaker field coils are intact. There are two, which energise the speakers and also act as smoothing chokes, as you're no doubt aware. One is 1,500 Ohms - the other is 7,500 Ohms. Hopefully they'll be OK, but if not, the 7,500 Ohms one will be a challenge to rewind. I've only rewound one field coil, which was 2,000 Ohms. That took about 2 Km of 38SWG wire (0.006" - about 34AWG). A 7,500 Ohm Coil would I think be of finer wire than that.
There is two sets of data-sheets available for the set - the Trader Sheet 557, and the 'Broadcaster' which runs to 3 pages. The later has drawings of the underside and top of the chassis rather than simply pictures, as on the Trader Sheet, and might be helpful to have. The Broadcaster Sheet shows C24 (not C23) mounted vertically to the left of the speaker (when viewed from the rear) close to the end of the chassis. You should be able to find a suitable sized tubular metal can replacement as near to the original as possible. C23 is shown mounted vertically underneath the chassis in the centre. (They're both 8 uF tubular).
I don't know anything about the set - these are just a few observations for what it's worth.
Very expensive set in its day - £18.18.0 GBP - about £1,100 GBP in today's terms.
In the depression years of the early 1930s, it would have been at least two month's wages for a working man, so would have ben out of the reach of all but the 'well off'.
Hope that helps a bit.
Good luck with the restoration Robert!
1) Yes, it will have had a back, and there's a pic of the top LH of the back at RMORG, but unfortunately, not the whole back. Sets of this era generated a lot of heat, and I believe it was commonplace in less safety conscious days to remove the backs of sets to allow more ventilation. To be able to faithfully replicate the back panel, what you really need is a 'brass rubbing' of a genuine one. By that, I mean not a drawing or a picture, but a piece of paper held against the back of the set then a wax crayon rubbed over all of the ventilation slots and other openings (for the mains flex etc) to accurately show the size, location and shape of the holes. Also, a pic of the back to show any labels such as valve types, operating voltages, make and model No. I've made quite a lot of replica backs for a range of radios in my collection using a router jig I designed for that purpose. The hardest part has always been getting good information about the size and shape of any openings, and the label size, text, font, colouring etc.
2) The set was introduced in 1933, and it's my guess that the paper-boxed electrolytic is a wartime replacement in the early 1940s when the set was around ten years old. A lot of appallingly bogged repairs were carried out during that era - sometimes by inexperienced apprentices too young to be drafted into the armed services, or older guys who were too old or too unfit for active service. Clearly anyone who was experienced and skilled in radio repairs would have found themselves called up in very short order! Typically, these replacement caps were just bodged in and left dangling on the wires wherever space could be found for them. I've attached a pic of one I found in an Ekco set I'm restoring (slowly!). It was just dangling under the chassis, the wires having been twisted together (not soldered), and wrapped in insulating tape. (You'll see the tape on the yellow wire in the attached pic).
3) The brackets look the same at each end on the RMORG pictures.
The thing that would worry me most about the set is whether the speaker field coils are intact. There are two, which energise the speakers and also act as smoothing chokes, as you're no doubt aware. One is 1,500 Ohms - the other is 7,500 Ohms. Hopefully they'll be OK, but if not, the 7,500 Ohms one will be a challenge to rewind. I've only rewound one field coil, which was 2,000 Ohms. That took about 2 Km of 38SWG wire (0.006" - about 34AWG). A 7,500 Ohm Coil would I think be of finer wire than that.
There is two sets of data-sheets available for the set - the Trader Sheet 557, and the 'Broadcaster' which runs to 3 pages. The later has drawings of the underside and top of the chassis rather than simply pictures, as on the Trader Sheet, and might be helpful to have. The Broadcaster Sheet shows C24 (not C23) mounted vertically to the left of the speaker (when viewed from the rear) close to the end of the chassis. You should be able to find a suitable sized tubular metal can replacement as near to the original as possible. C23 is shown mounted vertically underneath the chassis in the centre. (They're both 8 uF tubular).
I don't know anything about the set - these are just a few observations for what it's worth.
Very expensive set in its day - £18.18.0 GBP - about £1,100 GBP in today's terms.
In the depression years of the early 1930s, it would have been at least two month's wages for a working man, so would have ben out of the reach of all but the 'well off'.
Hope that helps a bit.
Good luck with the restoration Robert!
Regards, David.
BVWS Member.
G-QRP Club Member 1339.
'I'm in my own little world, but I'm happy, and they know me here'
BVWS Member.
G-QRP Club Member 1339.
'I'm in my own little world, but I'm happy, and they know me here'
