General Electric A-125
Other Interesting Radios
This page is preliminary and the links are not working yet. In time I will be adding content to the links. Thanks for reading!
This is General Electric's high end 1936 model.
According to Radio Retailing, it was the top of the line model, but I suspect there were bigger more grandious models for 1936.
This was the first model year of GE radios that were not connected with RCA. Prior to the 1936 model year, all GE radios and chassis had an RCA equivalent.
GE made a very elaborate tuning system for this model. The arrangement resembles in some ways a television tuner. The RF and converter stage along with all bandswitching is done on a seberate chassis called a "Sentry Box".
This method confines all RF bandswitching and tuning in one unitized chassis for better shielding and RF design.
The dial arrangement is an interesting one. It is an early use of a slide-rule scale.
The dial is on a drum which rotates to display each band separately, then a dial pointer slides along the drum to indicate frequency tuned.
The tuning mechanism has an automatic fine tuning/coarse tuning feature. As the tuning knob is turned, there is about one turn of fine tuning, then the mechanism switches to coarse tuning. Once the desired stationed is approached, all is needed is to tune slightly past the station, then back up. Fine tuning is engaged and you can easily tune the station.
The first thing I decided to do with this radio was to restuff the original electrolytic can capacitors which are fortunately still with it!!!
First remove the cans
Then, as I have in the past, I chucked the capacitor into a lathe and rotated it as I held an X-ACTO knife in the crease of the top cover.
The can is very soft aluminum, so doing this is rather easy.
There was some liquid in the 30 uf cap. Just the normal Borax stuff electrolytics used. Could dump it in with the laundry to boost the detergent! On second thought.... no....
Now to pull it apart
To me, it is amazing that the 30 uf has folded over plates and the 15 uf has spiral. It looks, to me, as if the 15 uf has more surface area for a capacitor, but evidently its the other way around.
I decided to use Solen Fast Capacitors as they are available in amazingly large size capacitances for the voltage ratings. They are NOT electrolytic, but they are polypropylene film types. Therefore they have amazingly low ESR and virtually zero leakage. Plus, they can handle significant AC current.
Yes, true, they are overkill! However, as I'm taking the time to restuff these things, which is NOT easy, I don't want them to fail anytime during my lifetime.
The Solens will last for an indefinite amount of time! Electrolytics will fail in time. It is their nature, unfortunately.
Next, I need to be able to connect the caps to the aluminum can. I do so by first, cleaning the aluminum the best I can with a small wire brush. Then using a small hobby butane torch, I heat the area to be soldered and apply aluminum solder. It actually does wet the aluminum well and sticks.
Immediately after the application of the aluminum solder, I apply regular 60/40 electronic solder to the aluminum solder with a soldering iron. It takes to it very well and provides an excellent connection point.
I have to thank member dtvmcdonald on www.antiqueradios.com for this idea!
Ok, getting ahead of myself here. I chose to use two 8.2 uf 630 VDC Solen capacitors in parallel for the 16 uf capacitor. I could not fit a 15 uf 630 VDC version inside. The two 8.2 uf caps just fit inside the can lengthwise.
Likewise with the 30 uf capacitor which is rated at 390 VDC. I chose two 15 uf 400 VDC Solens which almost don't fit into the can! It is a tight fit!
To attach the positive connection, I used a brass 6-32 screw with insulating washers and heat shrink tubing around the screw. Then reattached the solder lug to the screw with solder.
I simply solder the wire of the Solen cap to the head of the screw and insert it through the original rubber hole left after removing the insides of the capacitor. It has a piece of heat shrink around the screw and insulating washers to help keep shorts from occurring.
Once reassembled, the end coveres are cleaned and reattached with RTV Silicone rubber adhesive. I use the stuff as it holds well and will allow the caps to be reopened later, if needed.
I have used two-part epoxy, but it will not be as easy to open the can later.
Now, the caps are better than new and look pretty much as they did as original! Yes!
More to come!
Thank you for reading!