Kent 422 restoration

[bandersen]

Here's a little side project I've been working on in between TVs. It's a little four tube "midget" AM radio from 1940.

The tube lineup is

35Z5GT - rectifier
12SA7 - pentagrid converter
12SQ7 - detector and 1st audio
50L6GT - audio output

Conspicuously absent is an IF stage and I expect it will only receive strong, local stations.

Eventually I figured out the chassis is an Arvin (Noblitt-Sparks Industries) RE-91.

The handle appears to be a replacement and the glued on dial scale has seen better days. I'm going to strip and repaint it.
Not sure what to do about that scale. It's some kind of thin metal foil with a celluloid or plastic backing.



Here's a nice example from the radio attic: http://radioattic.com/item.htm?radio=0900035







The electrolytics have been replaced with some beefy ones rated for 450 volts and are too big to fit inside.
Also two are doubled up to get the necessary capacitance. Well I'll be replacing them with some "skinny" caps, of the right value and more modest voltage rating still well above the original.

The paper caps will get replaced with plastic film types. I spot checked a few resistors and they were way off so out they go too.

[bandersen]

Citri-Strip is working amazingly well. The old paint falls away in minutes

[Electronic M]

Nice.

For just a second on seeing that picture I thought it was a plastic cabinet, and that it had melted and cracked exposing the chassis ...

[dieseljeep]

I had several of those sets through the years. Even with the lack of an IF stage, they did receive remarkedly well. Living in Milwaukee, it received all the locals well, beside the Chicago clear channels, WGN and WBBM.
The pentagrid converter was better than the 4 tubers that used the Autodyne converter setup, such as Admiral, GE and Westinghouse.
IIRC, Arvin built that same radio for like 15 years running, with the Arvin and the Silvertone badging.

[maxm]

I have a version with a 3-tube chassis, which left room on top of the chassis for an electrolytic can.

(Sorry for the poor photos, these were taken years ago when digital photography wasn't as good as it is now.)

[old_coot88]

Ultra midget TRFs, and superhets with no IF stage were sometimes known generically as 'metro' radios.

Hey check out this puppy for stripping stuff..

https://www.youtube.com/watch?v=ppV-265zPrI

[dieseljeep]

Originally Posted by maxm

I have a version with a 3-tube chassis, which left room on top of the chassis for an electrolytic can.

(Sorry for the poor photos, these were taken years ago when digital photography wasn't as good as it is now.)

The set you have is a TRF.
Arvin also made a 2 tube model at around the same time using a 70L7 and the 25B8. The 3 tube model seems to be a better design.
The 25B8 has always been a hard to get and expensive tube.

[bandersen]

Was making steady progress until I discovered crumbly rubber wiring in the IF can. I decided the best course of action was to unmount, disassemble and rewire.











Also made some repairs on the speaker cone. Previous repairs were made with something like liquid electrical tape, but I refer diluted Aleene's Tacky glue.
It soaks into the paper resulting in a stronger cone, while remaining flexible and adding little extra mass.

After the glue on the tear set up, I went over the whole cone with diluted glue.

[bandersen]

Also made a lot of progress on the cabinet. After stripping, I removed the rust with Naval Jelly and primered. After a little sanding, I sprayed on some Navajo White gloss enamel.

[dieseljeep]

Originally Posted by bandersen

Citri-Strip is working amazingly well. The old paint falls away in minutes

I'm amazed that Citri-Strip works that well on baked-on enamel.

[dieseljeep]

Originally Posted by bandersen

Here's a little side project I've been working on in between TVs. It's a little four tube "midget" AM radio from 1940.

The tube lineup is

35Z5GT - rectifier
12SA7 - pentagrid converter
12SQ7 - detector and 1st audio
50L6GT - audio output

Conspicuously absent is an IF stage and I expect it will only receive strong, local stations.

Eventually I figured out the chassis is an Arvin (Noblitt-Sparks Industries) RE-91.

The handle appears to be a replacement and the glued on dial scale has seen better days. I'm going to strip and repaint it.
Not sure what to do about that scale. It's some kind of thin metal foil with a celluloid or plastic backing.



Here's a nice example from the radio attic: http://radioattic.com/item.htm?radio=0900035







The electrolytics have been replaced with some beefy ones rated for 450 volts and are too big to fit inside.
Also two are doubled up to get the necessary capacitance. Well I'll be replacing them with some "skinny" caps, of the right value and more modest voltage rating still well above the original.

The paper caps will get replaced with plastic film types. I spot checked a few resistors and they were way off so out they go too.

I think I have one of the pre-war models.
All the others I had were post-war models with the more stream-lined cabinet style. I even had one with the miniture tube line-up. That was the only one that came with a metal back. That model had better looking tuning and volume control knobs, instead of those boring old chicken-heads.
All the post-war octal models never came with a back. It was appearant that it never came with one, as the mounting holes were never used.

[bandersen]

I finished the recap, fired it up and it works Not much of a performer even after peaking the IF but I wasn't expecting much. I'll add a fuse and run a new power cord through the strain relief next.

[arvebe1248]

Your paint job looks spot on

[bandersen]

Thanks! Painting is really not something I enjoy doing but it came out pretty good this time

I upped the filament dropper form 47 to 68 ohms to compensate for higher line voltages. That will dissipate about 1.5 watts so I used a 5 watter to be safe.
Also installed a fuse, new power cord with strain relief and antenna.


I'm leaving off the old deteriorated dial scale for now. Not sure what to do about it

[Crist Rigott]

Thanks for sharing!