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 Post subject: Does anyone recognize this tube device?
PostPosted: Aug Fri 12, 2022 7:36 pm 
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Please comment if you know or have a guess about what this device is. I haven't traced it out at all. It's about the size of a lunchbox and weighs about 2-3 pounds. The closest thing I've ever found is an Atwater Kent device that looks similar, but I don't think they are the same at all.

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Last edited by 8alonzo8 on Aug Fri 12, 2022 8:39 pm, edited 1 time in total.

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 Post subject: Re: Does anyone recognize this tube device?
PostPosted: Aug Fri 12, 2022 8:14 pm 
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It appears to be a low frequency converter, it gets its power by pluging the speaker in to the converter and pluging a cord from the converter into the speaker socket in the radio .

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 Post subject: Re: Does anyone recognize this tube device?
PostPosted: Aug Fri 12, 2022 8:43 pm 
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battradio@ wrote:
It appears to be a low frequency converter, it gets its power by pluging the speaker in to the converter and pluging a cord from the converter into the speaker socket in the radio .

I meant to add the picture with the AC plug (I added it to my original post). The fact that it is powered by AC may not make a difference, but I'd like to know if you still think it's a low frequency converter or something else powered by AC.


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 Post subject: Re: Does anyone recognize this tube device?
PostPosted: Aug Fri 12, 2022 11:11 pm 
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Look at the dial , it goes from about 170 Kilocycles to 455 KC which is below the broadcast band . Not much if any broadcasting down there anymore .

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 Post subject: Re: Does anyone recognize this tube device?
PostPosted: Aug Fri 12, 2022 11:18 pm 
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battradio@ wrote:
Look at the dial , it goes from about 170 Kilocycles to 455 KC which is below the broadcast band . Not much if any broadcasting down there anymore .

Do you know what it is?


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 Post subject: Re: Does anyone recognize this tube device?
PostPosted: Aug Sat 13, 2022 2:30 am 
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Could be a signal generator for IF frequencies. 175, 260, 450 are marked on the dial. 60 Hz modulated, since there's no rectifier...

I though LF converter at first, but with only a single triode?

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 Post subject: Re: Does anyone recognize this tube device?
PostPosted: Aug Sat 13, 2022 5:26 am 
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Tom Bavis wrote:
Could be a signal generator for IF frequencies. 175, 260, 450 are marked on the dial. 60 Hz modulated, since there's no rectifier...

I though LF converter at first, but with only a single triode?

Thanks for pointing out those frequencies and taking a guess at what it might be, Tom. Because of the ornamental design of the case, it looks like it was meant to sit on a table top as part of a radio system. There is only an AC power plug, an off/on switch, and a single antenna lug. My original thought was that the antenna lug was an input, but your guess now has me wondering if the antenna lug could be an output.

If you know of any similar signal generator examples from approximately the same period that you can point me towards, I would certainly appreciate it. It sits on a shelf in my office as a reminder to look for information about it from time to time. I've searched for a few a couple of years, but I have never been able to find any data on it nor anything similar.


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 Post subject: Re: Does anyone recognize this tube device?
PostPosted: Aug Sat 13, 2022 2:12 pm 
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Being specifically marked at 175-kc, a very popular intermediate frequency in the early 1930s, it is a signal generator.

Norman

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 Post subject: Re: Does anyone recognize this tube device?
PostPosted: Aug Sat 13, 2022 2:14 pm 
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I, agree with Tom. A signal generator, the tube socket appears to be mislabeled.

In the late 20's early 30's simple circuits for bench instruments were common. The RCA Handbooks had such circuits the technician could build. The cabinets and such also available. The dial may also indicate it was a "teaching" kit offered by one of the many mail order training courses. For example NRI, DeForest, Sprayberry, etc.

Trace the circuit and draw a true schematic of the signal flow and feed back, very likely via the transformer. Often the schematic will reveal what it was supposed to do.

It is unusual to use an antenna for a signal port, then again a mislabel? May also function as a BFO, that is, if one does not mind an AC note on the CW signal.

Chas

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 Post subject: Re: Does anyone recognize this tube device?
PostPosted: Aug Sat 13, 2022 2:42 pm 
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The black piece that the tuning shaft turns appears to have "DeJur Newark NJ USA" stamped into it. Not positive since some of it is obscured.

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 Post subject: Re: Does anyone recognize this tube device?
PostPosted: Aug Sat 13, 2022 4:23 pm 
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Joel, you are correct. It is stamped "DeJur-Amsco New York, USA". A couple of searches revealed they made a lot of products aimed at the photography market. The only place I found the stamp was on the tuning mechanism. A few patents are also stamped just below the name (1657259 is the only one that I can see clearly without removing parts) which I searched for, but that did not produce any results.

Per Tom, Norman, and Chas, it looks like the general consensus is that the device may be a signal generator. The information from Chas about it being a bench tool is something I had not considered or ran across yet, which is helpful since I was looking at something a consumer might buy for a set rather than a tool supplied in a kit. That, coupled with the other information about the frequencies on the dial really make more sense now. I will start looking with that in mind.

One more question. :lol: Chas mentioned that "...the tube socket appears to be mislabeled...". I did notice the SPK markings on the socket, but I took it as a makers mark and never thought about it again. Maybe that tube was never meant to be there in the first place and a PO just found a tube that fit there(??). Could that be a speaker connector?
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 Post subject: Re: Does anyone recognize this tube device?
PostPosted: Aug Sat 13, 2022 4:48 pm 
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DeJur & Amsco were both Bakelite electrical product molders and manufacturers. They supplied these components to distributors and product manufacturers.

Drawing the schematic will usually reveal what the instrument does. I do suspect that the tube is a 27 but it could also be a "hole filler".

Chas

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 Post subject: Re: Does anyone recognize this tube device?
PostPosted: Aug Mon 15, 2022 2:55 am 
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A homebrew generator, made with a few scavenged parts. Besides the speaker socket repurposed for the 27, the output terminal post was once labeled "Short Ant" (antenna), which has mostly been scratched off. Hobbyists in the 1930s had to be frugal.

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 Post subject: Re: Does anyone recognize this tube device?
PostPosted: Aug Mon 15, 2022 6:30 pm 
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Tim Tress wrote:
A homebrew generator, made with a few scavenged parts. Besides the speaker socket repurposed for the 27, the output terminal post was once labeled "Short Ant" (antenna), which has mostly been scratched off. Hobbyists in the 1930s had to be frugal.


This is the most likely guess so far.

Looks homebrew to me too, using mostly repurposed parts.


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 Post subject: Re: Does anyone recognize this tube device?
PostPosted: Sep Fri 02, 2022 5:34 pm 
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Location: Houston, TX
Thanks for all the guesses, information, and comments. I learned quite a bit about the homebrew side of things just reading through the comments and looking for other related information those comments led to, so I am glad I posted this. I didn't realize homebrew could be so detailed and well done. Quite a nice set of skills to be able to think of a tool you need then make it out of stuff you have on hand, especially back when you might not have had a way to research or collaborate the way we do today. I like the case, but I think this little device looks best with the cover off. The build just looks...cool. I'll take a shot at creating a simple schematic (crude as it will likely be) for the device as received when I have a bit more time. I'll post it as a follow up on this thread when I do. Thanks all.


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