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Old 17th January 2016, 03:43 AM   #1
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Default 1934 RCA Radio

Hi guys,

Got this in a cardboard box. No info, but I dug up the information and the schematic. Should be a fun project. I got no nine year old kid to show me how to make a video so....this is a test....lol

https://youtu.be/CwhwWeeDqKQ

How did anyone survive back in the 19 hundreds without killing themselves!!...lol

Cheers,

Billy
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Old 17th January 2016, 09:22 AM   #2
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The chassis was not exposed and look at the insulation on the control knobs, 3/4" of Bakelite! In the old days, wireless sets were installed by the local repair man and the live chassis sets, like most of them then, had the chassis connected the neutral or earth.
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Old 17th January 2016, 01:44 PM   #3
gofar99 is offline gofar99  United States
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Hi, Even into the 50's the classic 5 tube all American AM radio had a live chassis. Many phonographs did as well. Anyone else remember the mono tube phonos with either a 25L6 or 35L6 in series with the motor? Like it was said amazing how any of us survived. How many of the line powered TVs were in the kitchen or bathroom?
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Old 17th January 2016, 06:47 PM   #4
DF96 is offline DF96  England
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Be aware that discussion of live chassis equipment is severely frowned on here. Unless you really know what you are doing you should use an isolation transformer to keep you and your family safe.
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Old 17th January 2016, 07:23 PM   #5
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Quote:
Originally Posted by gofar99 View Post
Hi, Even into the 50's the classic 5 tube all American AM radio had a live chassis.
I know they did, and it was hilarious how they were advertised: "AC/DC radios" instead of: "We're too cheap to include a proper PTX so's you don't fry yourself". It might not be so bad so long as everything was insulated from the end user. Yet, how many replaced a broken knob with a pair of pliers? How many did unauthorized modifications that essentially defeated the live chassis isolation?

At least the 1934 RCA radio discussed here has a PTX. I don't recall seeing one that didn't. Though I wouldn't ever consider powering up after who knows how long it's been laying about, the electrolytic capacitors well beyond their shelf life and drying out all these years. I'd definitely replace these routinely.

Quote:
Many phonographs did as well. Anyone else remember the mono tube phonos with either a 25L6 or 35L6 in series with the motor? Like it was said amazing how any of us survived. How many of the line powered TVs were in the kitchen or bathroom?
Seen schemos of this, but never actually seen one in the wild. Really: SE pentode operation without a trace of NFB. These things must've sounded hideous. I've seen plenty of AA-5 radios that used 50C5 finals in SE (no NFB at all) with tiny OPTs. Yet the spec sheet for the 50C5 includes -- not one -- but two sets of plate characteristics. One for V2K= 110V, and a more linear set for V2K= 90V. Makes one wonder why they bothered if no one ever connected them to a decent OPT.
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Old 17th January 2016, 07:41 PM   #6
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At least the 1934 RCA radio discussed here has a PTX. I don't recall seeing one that didn't.
Most radios from the 30's and before have power transformers, or ran entirely on batteries. The series string tubes that started the transformerless era came in the late 30's and early 40's.

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Anyone else remember the mono tube phonos with either a 25L6 or 35L6 in series with the motor?
I had one of those somewhere in the 60's. The tube (it only had one) was missing when I found it. I tried what ever tubes I had until I found something that worked, sort of. You had to spin the record up by hand, but once up to speed, it played.
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Old 17th January 2016, 08:37 PM   #7
gofar99 is offline gofar99  United States
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Hi I absolutely agree on the horrors of AC/DC powered gear. On the bright side though I restored a Philco "barn" radio some time ago. It originally ran on batteries. I constructed a safe isolated power supply for it as the batteries were no longer available. I even found that Antique Electronic Supply (tubesandmore.com) had the original grill cloth for it. A fun project and the only thing that could not be saved was the speaker. There was no cone left in it. It was a 1939 radio BTW.
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Old 17th January 2016, 11:25 PM   #8
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Quote:
Hi, Even into the 50's the classic 5 tube all American AM radio had a live chassis.
I know they did, and it was hilarious how they were advertised: "AC/DC radios" instead of: "We're too cheap to include a proper PTX so's you don't fry yourself".
Yes, AA 5 radios were cheap and dangerous. Atwater Kent chose to to go out of business, instead of make AA 5s. However, AC/DC is not 100% about profit. From personal experience, I can tell you that some areas of NYC's Greenwich Village had DC house current into, at least, the 1970s. Obviously, a power trafo does not work when DC "juice" comes out of the wall.

Some time ago, somebody put up a commercial AC/DC schematic that approached HIFI. The O/P iron had a separate NFB winding and the speaker connections "floated". Provided the HIPOT capability of the "iron" is good, such a setup can be made reasonably safe. Still, don't build without a power transformer.
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Old 18th January 2016, 12:59 AM   #9
kevinkr is offline kevinkr  United States
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I have a modestly restored Atwater-Kent 310/510 chassis dating from 1932. The wet slug electrolytics and some wire was all that was wrong with it after all of these decades. All of the resistors and capacitors are fine, and would be unrecognizable as components today. There is a surprising amount of resistor wire in this thing as well. Unfortunately I did not get the speaker that should have come with it as the person who gave me the radio did not realize the speaker was also important. In this radio the speaker had a PP output transformer and field coil. Both have now been substituted with external transformer and choke.

I found the right speaker on eBay once (in fact I had reason to believe it was from the same radio given the seller location) but was unable to snag it.

I cut the tops off of the electrolytics and installed modern capacitors inside the original cans and epoxied the tops back on.
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Old 18th January 2016, 01:40 AM   #10
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All this talk about AA5 radios reminds me of the first electronic kit I built as a 13-or-so year old kid. Can't remember who made the kit, but I'm thinking it was from a Lafayette Electronics store (anyone remember those?). I think I still have it buried somewhere in the house. Might make for a fun restoration and trip down memory lane.
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