Dumont RA113 "Burlingame" restoration

[bandersen]

A few weeks ago Phil Nelson put me in touch with the owner of this nice Dumont RA113. He and his brother grew up with this set and he really wanted to get it restored to working condition.

Although I've plenty of other projects, I agree to take a break from them and work on it. They pulled up in front of my place with it yesterday afternoon.

I removed the chassis while it was out on the curb to lighten the load but the cabinet was still quite heavy.

The set had been kept inside it's whole life and is in very good condition. The finish looks very similar to my blonde Sentinel so it's probably also made from Korina wood. As best they can remember it is working when retired from service.

There's a ding on both cabinet sides from the door handles whacking into them. Seems they should have used a little bumper like on Zenith portholes.


The CRT had been replaced with a Westinghouse 17BP4B back in the late 50s and the set saw very little use afterwards. Even so I was surprised at how quickly it showed emissions well into the good with excellent cutoff and rock solid life test.


The tube chart shows a 17AP4. The back does not have a cutout for the CRT but luckily the 17BP4 just fits.


The chassis is rust free and quite clean


I see a few replaced caps but it's mostly original.


It also appears that a HV anode lead has been spliced it. Perhaps the original 17AP4 had a different type of HV cap ?

[holmesuser01]

I love seeing other RA-113's!

This one is a pretty example.

I've had to hold off on the restoration of my mahogany DuMont for now, but will be getting back on it during the winter, when I don't like going outside very much. I had to find a power transformer for mine, but thanks to a great internet friend, it was located, so that major hurdle was overcome.

I look forward to seeing progress on this set as it is brought back to life,

[IsthmusTV]

Hi Bob,

Very nice find! It looks exactly like the one I'm beginning to restore. I, too thought it was a "Burlingame" but I now believe that it is a blond version of the "Revere." Mine is model number RA-113-B4. I'm just in the process of putting together a cap order. (It's the one I picked up in Kenosha last month for $55.) Here are a few photos:




My CRT is the original DuMont 17AP4 which tests good. Should be a fun restore. Good luck!

-Clark

[bandersen]

Originally Posted by IsthmusTV

Hi Bob,

Very nice find! It looks exactly like the one I'm beginning to restore. I, too thought it was a "Burlingame" but I now believe that it is a blond version of the "Revere."...

Right you are. I didn't notice the difference in legs when I looked at the models on Phil's website.

It's not my set though - I'm restoring it for someone. I did consider going for the set you got but it's much too big for my place. The sooner I get this done and out of here the better

[Phil Nelson]

I wouldn't have guessed it beforehand, but that cabinet's attractive in blonde.

I think the RA-113 is an interesting & fun set to restore -- enjoy!

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

[Kevin Kuehn]

Very nice sets. I have a much rougher one around here some place I've been working on. Will be fun to watch you guys restore these

[kramden66]

17AP4 was a metal cone wasn't it ? if so that would explain the splice because you would have to change the anode to fit a 17BP4

mike

[IsthmusTV]

It also appears that a HV anode lead has been spliced it. Perhaps the original 17AP4 had a different type of HV cap ?

The anode connection on the 17AP4 looks the same. Mine has a quick disconnect inline with the anode lead (as does Phil's). It looks like that was removed on that set. You can see one end of it hanging in this photo. And the 17AP4 is an all glass CRT:


I noticed that the focus control on mine looks pretty bad (green corrosion on the element wire). I haven't tested it, but I preemptively ordered the same replacement Phil used from Surplus Sales of Nebraska since I know these are a common failure point.

It's not my set though - I'm restoring it for someone. I did consider going for the set you got but it's much too big for my place. The sooner I get this done and out of here the better

I hear ya, these suckers are big. I'm not quire sure where I'll put mine yet

I'm very fortunate to be restoring a set that now two masters, Phil and Bob, are blazing the trail!

-Clark

[Eric H]

Those are some very nice blondes! Usually the finish is all beat to heck on the blonde stuff.

[bandersen]

I think it's because they used an actual light hardwoord rather than "limed oak" type finish.

[bandersen]

I finally have the chassis up on the workbench. First I'm going to pull the 5U4 rectifier and power it up to make sure the power transformer is OK.




Do you guys think this ASC 1,000 pF, 10kV cap is a suitable replacement for the original 500p HV caps ?

[kramden66]

it might work , I used 470pf caps from moyer that were 10kv or 15kv that are round in similar applications and they worked.

mike

[earlyfilm]

Originally Posted by bandersen

Do you guys think this ASC 1,000 pF, 10kV cap is a suitable replacement for the original 500p HV caps ?
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When most rebuilders got a 17AP4 dud, they would rebuild it as a 17BP4 or, if they could aluminize, as a 17BP4B, since as these newer types were more marketable and used the same bulb.

Since the maximum external coating capacitor on a 17AP4 was 500 µµF greater than on the replacement 17BP4, you are still within factory specs on the HV to ground capacity in the CRT circuit. This is the capacitor that you sometimes hear warnings not to increase due to the potential shock hazard.

Increasing the other two 500 µµF 10KV capacitors to 1000 µµF would allow the second HV rectifier to operate more efficiently, but the tiny HV increase and extra loading on the HV output tube and Flyback should be minimal.

I'm impressed by how beautiful the insides of that set is!

Jas.

[bandersen]

Thanks for the info. I'm also considering using some ceramic HV caps as they are a lot less expensive.

The power transformer is good and the tuning eye is showing signs of life
I get some HV with the old caps still installed, but it's definitely less than it should be. I expect new caps will take care of that.


Making steady progress with the recap. Those old caps are very sticky and gooey

[IsthmusTV]

Making steady progress with the recap. Those old caps are very sticky and gooey

The caps in mine were all gooey, too. I had to use Boraxo to get the gunk off my fingers

Looking good, Bob. I'm curious to see how the ceramic caps work in the HV doubler.

-Clark