This was an antique/junk store find. The sewing cabinet table contains a 320 Chassis and the combination is a 320-T manufactured around 1938. There is a 1938 advertisement that describes it as a replica of a sewing table found in "Furniture Masterpieces of Duncan Phyfe" and made of Honduras swirl mahagony.
The front has a nasty break that was "fixed" at one point and has failed again. I'll also have to fashion up an escutcheon somehow since the original is crumbling.
The rest of the cabinet is in reasonably good shape and should refinish nicely.
The chassis was very dusty but also has had some work done to it in the past.
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This set uses a battery as a bias and a "replacement" Ray-O-Vac had been soldered in. There is a white pincher like device that is also connected to the same place the battery is so I suppose that it was the holder for the original bias cell although I have never seen one before.
At this stage I'm just cleaning off the years of grime and taking out the old dried up tuner and speaker mounting rubber. I'm waiting for an order from Renovated Radios for some replacements.
Hello klondike98,
What great looking set !
Far as Chassis go it is in fairly nice shape and the cabinet looks nice too .
Sincerely Rich
Here's a bias battery for an RCA 28T set I worked on. I replaced it with a lithium button cell.
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I believe the bias battery can be eliminated by altering the cathode bias and adding a grid resistor of a high value. At the time of production, stable high value resistors were not available for that service. The battery was a relatively reliable alternative and will often out last the 5 year life of the radio as no current is drawn... chas
Just my two cents, you could also buy a single cell battery holder for an AA cell, and make any future changes simple. Once you rebuild the original electrolytic cans, and get rid of those big orange replacements under the chassis, there should be a whole lot more room. If you don't bother with re-stuffing the paper condensers, but just go with the yellow poly condensers as is, you'll have even more room. Should be able to find a place for an AA cell holder pretty easily.
Thanks Mike, good thought.
The watch batteries work but the polarity is the opposite of one of those vintage Mallory bias cells. With the style I run into in Rogers sets, the kind with the cylinder that fits the domed side, the cylinder is negative, and the spring contact is positive, so you have to rewire them to use the modern watch batteries which have the case as positive. I don't think the availability of one type of resistor or another had much to do with why bias cells were used, I've never seen a radio older then 1936 that had them, the newest set I have seen with them was a Canadian Marconi set from 1941. They claimed that it was to simplify the power supply, but since the usual method was to place a resistor, and cap, in series between the cathode of the tube, and ground the parts count would be negligible. I'm guessing that it was either to create a service item that would create extra business for repair shops (keep in mind that other then electrolytic caps the paper caps seldom needed replacement when these sets were under 10 years old), or that it was a scheme to avoid paying patent royalties. Weird that a Stromberg would use one, all the ones I have encountered do not, and Stromberg didn't care about patent royaties, they just paid them.
Ifg the set has all original caps I would restuff the paper ones, and the cans on top, there seems to be more then enough room for everything under that chassis.
Regards
Arran
Thx Arran. I was thinking that most of the resistors were no longer original and a few paper caps are replaced already so wasn’t thinking of stuffing the paper caps. Do those carbon resistors look like 1938 vintage to you?? If they are then I will go ahead and stuff the paper caps also.
I can't see most of the resistors, but the ones I can see look like replacement carbon comp ones by the way the leads are dressed, there are metal oxide ones that are brown, so they don't look out of place. I can't remember what style of resistors were used in the two 1937 models, but I don't think they had dogbone style ones . I usually restuff paper caps because I can't stand the way the yellow plastic ones look in a pre war radio, more so then keeping it all original, replacement resistors don't bother me as much unless they are bright blue. some were replacements it was probably the audio coupling caps like the one on the volume control, and the one between the plate of the 1st audio, and the grid of the power output tube. The most obvious replacements are the axial lead filter caps under the chassis electrically replacing the cans on top.
Regards
Arran
Nice work Bob
The clamps cover your incisions well. It's always interesting to see a slightly different approach to re-stuffing.
A little more movement on this one...basically the right half or so of the underside of the chassis recapped. Most of the resistors were also well out of spec and replaced.
BEFORE and AFTER