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 Post subject: RCA Experimental Tube Identification
PostPosted: Sep Fri 03, 2021 1:08 pm 
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Joined: Sep Fri 03, 2021 12:47 pm
Posts: 4
Hi Group,

First post, thanks for the add.

I have a tube that was handed down to me from my Grandfather that I am trying to identify/determine the age of. Here is what I know about it:

- Looks to be a triode with directly heated cathode
- It has an RCA symbol on one side of the glass envelope
- It has a "W" with something illegible (in the shape of a hot dog) underneath, is the W for Westinghouse?
- 4 pin brass base with one larger, longer pin
- The base has some writing stamped on it, this is what is says as best I can make it out: RCA ONLY FOR EXPERIMENTAL (illegible, ending in T) USE
- The filament is open so it is more of a conversation piece/collectors item than a viable tube

Attached are some pictures.

Thanks for any information anyone might have.

Regards,

Robert Entwistle, WA2T


Attachments:
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Tube2.JPG
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Tube3.JPG
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Tube4.jpg
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Tube5.JPG
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 Post subject: Re: RCA Experimental Tube Identification
PostPosted: Sep Fri 03, 2021 5:01 pm 
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Joined: May Tue 05, 2020 5:08 pm
Posts: 96
Location: Youngstown, OH
It looks like a WD-11.


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 Post subject: Re: RCA Experimental Tube Identification
PostPosted: Sep Fri 03, 2021 9:25 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1239
Location: St. Louis, MO, USA
I think the white material on the glass pinch is a lime getter used to eliminate the las bit of gas in the tube.

Dennis


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 Post subject: Re: RCA Experimental Tube Identification
PostPosted: Sep Sat 04, 2021 4:13 am 
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Location: Tucson, Arizona U.S.A.
In the beginning, General Electric and Westinghouse banded together to form RCA to sell their products. So it might very well have both brands. RCA didn't make anything at that time.

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 Post subject: Re: RCA Experimental Tube Identification
PostPosted: Sep Sat 04, 2021 4:22 am 
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It isn't an experimental tube. The text probably said that it was licensed only for amateur, experimental, and replacement use or something like that. Lots of early tubes have this kind of message. The point being that it wasn't allowed to be used by manufacturers; they had to have an agreement with RCA.

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Jim Mueller

Who's that swimming in the punch bowl?
It's Walter Wart, the freaky frog!


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 Post subject: Re: RCA Experimental Tube Identification
PostPosted: Sep Sat 04, 2021 5:33 pm 
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Joined: Sep Fri 03, 2021 12:47 pm
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Airway Radio Fan wrote:
It looks like a WD-11.


I think you are right! Thank you.


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 Post subject: Re: RCA Experimental Tube Identification
PostPosted: Sep Sat 04, 2021 5:34 pm 
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Joined: Sep Fri 03, 2021 12:47 pm
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Thanks Dennis and Jim, this helps a lot.

Regards,

Robert


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 Post subject: Re: RCA Experimental Tube Identification
PostPosted: Sep Sun 05, 2021 9:15 pm 
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Joined: Jun Fri 19, 2009 6:34 pm
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Location: Long Island NY
What you have there is a brass based, tipped WD-11 tube which probably dates to 1922 or 1923. The WD-11 was introduced by Westinghouse in 1922 and sold by them in a line of small receivers dubbed "Aeriolas" as broadcasting developed around their Pittsburgh station KDKA. Many consider it the first mass-consumption radio tube.

RCA itself was formed in 1919 as a consortium of Westinghouse, General Electric, AT&T, and the United Fruit Company to exploit Ernst Alexanderson's alternator radio transmitter by buying out American Marconi (which was set to acquire the rights to the alternator from GE). They needed the patents and holdings of all four companies to build a complete, end-to-end radio communications system. Originally all RCA did was run the wireless and shipboard radiotelegraph business it inherited from American Marconi, but the success of the 1920 KDKA Harding-Cox broadcast was one of the things that caused RCA to go into broadcasting and selling radios to the public. They decided that rather than compete against each other, GE and Westinghouse would do the manufacturing of tubes and equipment and RCA would be the sales organization. Thus your Westinghouse tube has both their logo and RCA's.

What the little sticker referring to "licensed for experimental and amateur use, etc," is all about is the cross-license agreement between AT&T and other the companies. AT&T had purchased nearly all of Lee De Forest's vacuum tube patents and had earned numerous others as it researched and developed tubes for various purposes. They also had patents on public address systems and sound motion pictures. So what they were saying was the tubes were only cross- licensed to RCA for home or amateur use in radios; if you wanted to use them commercially in a telephone system, a broadcast station, or for PA or theater sound systems where an admission fee was charged, you'd likely have to buy different tubes, the prices of which included additional royalties to AT&T. As was pointed out above, many tubes and radios carried similar license notices for many years.

The WD-11 is a triode with a 1.1-volt filament intended to be lit by a 1.5-volt dry cell with a rheostat in series. The filaments were not very robust and burn out easily so good ones are relatively rare and demand high prices from collectors today. The short lives of the tubes was a major drawback and just a year after it was introduced Westinghouse superseded the WD-11 with the WD-12 while GE brought out the very popular UX-199 tube. After 1924 no new commercially made radios used the WD-11 and adapters were put on the market allowing people to substitute 99 tubes for them. You can test the filament with an ohmmeter to see if it has continuity; with the pins facing you, hold it so the large pin (which connects to the plate) is at 12:00. The two pins to either side, at 9:00 and 3:00 are the filament connections. The remaining pin at 6:00 is the grid. You should get continuity from the 9:00 pin to the 3:00 pin but no connection to either of the other two. I would not recommend attempting to light one of these tubes up today; if the filaments burn out they still have value as display duds but not nearly as much as ones with intact filaments.

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 Post subject: Re: RCA Experimental Tube Identification
PostPosted: Sep Sun 05, 2021 10:47 pm 
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Joined: Mar Wed 16, 2011 10:44 pm
Posts: 2050
Location: Peekskill, NY
This has the so-called Southerlen lime getter. Even as a dud (which as mentioned it might not be) it's a piece of history worth saving.


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 Post subject: Re: RCA Experimental Tube Identification
PostPosted: Sep Mon 06, 2021 10:45 pm 
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Joined: Sep Fri 03, 2021 12:47 pm
Posts: 4
Thanks for all the excellent information guys!

My tube is indeed a dud but I thought it was rare, glad I asked. Not sure if I will keep it, I might like to pass it on to a collector.

Thanks again.

73,

Robert Entwistle, WA2T


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 Post subject: Re: RCA Experimental Tube Identification
PostPosted: Sep Tue 07, 2021 2:27 am 
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Location: Ohio 45177
Would certainly be desired by someone with an Aeriola that wanted to display the proper early tipped tube in their radio for show. As for mine, I have a later C-11 replacement tube in it and at least one or two good spares. They will last if care is taken to run them at their minimal filament voltage to obtain enough emission to operate without pushing it. A strong one will oscillate even though you can hardly see it in a dark room.

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