RCA T4-8

I rescued this nice old cathedral radio from a flea market stand. The cabinet was in really lousy shape, so I got it cheaply. It would be a test of how much I could do to repair cabinets. Technically it looked rather good, so I didn't expect major problems in getting it to work.

But the cabinet!!! A lot of veneer was missing, most of the rest was loose, there were deep scratches, dents, water damage, and even a well intended but very poorly executed previous repair, where someone tried to replace a large chunk of original veneer by a piece of chipboard covered in eucalyptus veneer, tinted a bit darker! That's clearly visible in this photo, which shows the radio in the condition I got it.

Here is a close-up of the lower right section. Veneer is missing, loose, there is a non original RCA Victor label glued on with shoemaker's glue, you tell it...   Note that these photo shows something I discovered only later: Under the non original label, there are remains of the original one! Look under the C in "Victor" !

After removing that label, here is the original one. It seems to be made from papier-mache. I removed it for restoring the radio, but the label is in such a flimsy condition that I don't know how to repair it. I still have it stored today, waiting for someone to tell me what to do...

Electronically the radio was in a very much better shape. Some incapable individual had tried to repair it, and totally disaligned it in the process, mixed up the speaker wires, but he did no more damage. It was easy enough to replace the two faulty capacitors, realign the radio, and it went to work quite beautifully! And it's specially interesting to note that all four tubes still seem to be the original ones!

This radio must be about the simplest possible design for a superheterodyne. It uses a 6A7 pentagrid tube as an oscillator/mixer, followed by a 6F7 pentode IF amplifier. The diode in the 6F7 is used as a detector, and the resulting signal directly drives the type 41 power amplifier! There is no volume control in between, rather the volume control is a wire rheostat that controls the cathode current of the 6A7 and 6F7!

There is no automatic gain control. It had not yet been invented. If you tune from a weak station to a stronger one, you get ear shattering volume until you turn the control down!

The rectifier is a 1-V single diode tube, and the power supply uses the speaker field coil for a choke, as was usual in that time. Note that all four tubes have 6.3 V AC filaments, which had just appeared on the market. This was a simple, but modern radio in its time!

This label is glued to the inside of the cabinet. I love RCA's custom of referring to the tubes by their trademarked term of "Radiotron"!

This specimen is neither the A, B or C type. It's an export version, with an universal power transformer that has taps for pretty much everything from 75 to 250 V.

The label stuck on the right side is the warranty card, stating the chassis number, order number, and sale date. The date is interesting: September 17th, 1935!  It's interesting because september 18th is Chile's national holiday! People paint their houses, buy new clothes, and set everything up for a big barbecue for that day. Obviously someone decided to celebrate the 18th in proper form, and acquired A RADIO!!!  Maybe the first thing he listened to on this radio was the traditional speech of the President, which has been radioed every year since broadcasting started in Chile.

The fields for the 1st and 2nd checkup on the warranty card are empty. Obviously the owner trusted the radio so much that he deemed unnecessary to bother about keeping his guarantee valid.

And this is the label of the company that imported and sold the radio. Older people in Santiago still remember it. The label is crafted from brass and black lacquer, and fixed with small nails to the inner rim of the cathedral cabinet.

This is how the radio looked after full restoration. Only the papier-mache RCA label is still missing. The radio looks shinier on the photo than it really is, because of the flash lighting, which also casted an ugly shadow that visually distorts the shape of the radio. Sorry for the bad photo...

To restore this cabinet, I started by removing everything non wooden from it. Then I removed the non original label, removed and stored the original one, and removed the chipboard fix done by that other guy. Then I looked through my entire wood collection for some veneer that was similar to this radio's one, and came up with a scrap of Coigue wood. It's not the same, of course, but with some tinting it would not be too different. I crafted the necessary filler pieces and glued them in, using sandpaper to wear them enough to match the rest of the radio's surface.

Then I stripped the remains of the original finish. I don't like doing this, but it was unavoidable in this case. While stripping it (using solvents and soft steel wool) I cared to thoroughly impregnate the new wood patches, so they would take some of the original color.

After the radio had dried, I applied water based walnut stain. I worked to apply more stain to the new wood than to the old one, to make the colors match better. In addition, I tinted the entire radio slightly darker than it was originally, simply because it's harder to see the wood differences in a darker radio! Sorry for being an "unoriginal restorer" here, but I made it just a tad darker than it was...

Lacking spraying equipment when I restored this radio, I used the age-old french rubbing technique to apply some 25 coats of lacquer. This is a lot of work, but it's beautiful work.

The speaker cloth was removed from its cardboard base, hand washed in cold water, using rather strong detergent to get out 60 years of cigarette smoke, then rinsed and dried between towels. It came out beautifully clean and undamaged. I backed a worn spot with a scrap of thin clear fabric, and then reinstalled it.

Installing new rubber feet and then reassembling the radio completed the restoration. Except for that damaged papier-mache label, which still is stored away, waiting for some fix.

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