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 Post subject: Loktal 7B7 with RCA label?
PostPosted: Aug Thu 04, 2022 4:40 pm 
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Does anyone know the story behind RCA Loktals?
Did they rebadge Sylvania tubes?


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 Post subject: Re: Loktal 7B7 with RCA label?
PostPosted: Aug Thu 04, 2022 6:46 pm 
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I thought everyone rebadged everyone else's tubes, depending on the situation.

Probably RCA didn't make it. Better to resell someone else's gapfillers than to not be a full-line distributor. Cheaper than tooling up if you don't see big sales coming, too.


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 Post subject: Re: Loktal 7B7 with RCA label?
PostPosted: Aug Thu 04, 2022 11:13 pm 
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Most likely Sylvania. I doubt RCA would go the expense of tooling up for loktals when they weren't as common as other types

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 Post subject: Re: Loktal 7B7 with RCA label?
PostPosted: Aug Fri 05, 2022 11:38 am 
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I do not believe RCA ever manufactured Loktals in its own plants. Aside from Sylvania, they could have sourced them from Tung Sol or KenRad which were also set up to produce that style of tube.

With the exception of some smaller companies that made specialized tubes for niche markets, nearly all the large tube companies traded with each other on a wholesale level. It was not economical for one company to create all the tooling and jigs needed to build every type of tube they carried, so they would buy the types from each other that they did not want to make themselves. Indeed, I have heard it said that companies like Sylvania, RCA, GE, and so forth had their competitors' branding stencils on hand so that if company 'A' ordered a batch of tubes from company 'B,' they would arrive already printed and labeled, ready to be boxed in the purchaser's packaging. Sometimes you can get a clue of what happened from the EIA factory code on the side of the tube if it is still visible, or from the type numbers. The styles of the type numbers were unique to the production line so sometimes you'll see the RCA octagons, Sylvania style print, or GE "dot matrix" tube numbers on tubes with competitors' logos on them.

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 Post subject: Re: Loktal 7B7 with RCA label?
PostPosted: Aug Fri 05, 2022 12:12 pm 
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I am sure that Chris has touched on the specifics. As mentioned, you can often look at the marking on the tube, the sand etched dot matrix marking by GE, the type of "ink" and font for a Sylvania and the RCA "Stop Sign". For that matter, the 7591 tube was sold by many different manufacturers. But I am sure that RCA never made them; rather they bought them from either Westinghouse or Sylvania.

Lud Sibley has a good book out with tons of information about this subject.

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 Post subject: Re: Loktal 7B7 with RCA label?
PostPosted: Aug Fri 05, 2022 7:37 pm 
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A book, you mean like with paper pages? :D

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 Post subject: Re: Loktal 7B7 with RCA label?
PostPosted: Aug Fri 05, 2022 10:15 pm 
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westcoastjohn wrote:
A book, you mean like with paper pages? :D

Yes, they actually still make books. Sometimes, they are easier to digest.

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 Post subject: Re: Loktal 7B7 with RCA label?
PostPosted: Aug Fri 05, 2022 11:10 pm 
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Don Cavey wrote:
westcoastjohn wrote:
A book, you mean like with paper pages? :D

Yes, they actually still make books. Sometimes, they are easier to digest.


That's true, some of those tube manuals on cd are pretty hard to chew :wink:

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 Post subject: Re: Loktal 7B7 with RCA label?
PostPosted: Aug Sat 06, 2022 5:08 am 
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Can you please post a photo of the top of the bulb? Thanks.


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 Post subject: Re: Loktal 7B7 with RCA label?
PostPosted: Aug Sat 06, 2022 5:28 pm 
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igolioto wrote:
Can you please post a photo of the top of the bulb? Thanks.
Sorry, it is a picture from a seller's listing.

I just had no idea RCA was interested in supplying the Loktal market. Newer logo on the box, so maybe 1960's?

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 Post subject: Re: Loktal 7B7 with RCA label?
PostPosted: Aug Sat 06, 2022 5:38 pm 
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tubes4life wrote:
Don Cavey wrote:
westcoastjohn wrote:
A book, you mean like with paper pages? :D

Yes, they actually still make books. Sometimes, they are easier to digest.


That's true, some of those tube manuals on cd are pretty hard to chew :wink:
How about Reader's Digest? - the ultimate fast food for the mind.
I do read books, 2 pages a night. My son teaches English, and he definitely loves books too.

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 Post subject: Re: Loktal 7B7 with RCA label?
PostPosted: Aug Sat 06, 2022 5:52 pm 
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given the tube is this one,

https://www.ebay.com/itm/353998871165?h ... SwmdFiUDYP

It was made by Sylvania, as evidenced by the Sylvania date code at the top of the bulb, below the etched octagon designation.


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 Post subject: Re: Loktal 7B7 with RCA label?
PostPosted: Aug Mon 08, 2022 7:04 pm 
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Thanks for tracking it down. 8)


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 Post subject: Re: Loktal 7B7 with RCA label?
PostPosted: Aug Tue 09, 2022 7:06 pm 
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Out of interest, I am currently working on a Canadian Philco model 46. It has 4 Loktal tubes (plus a 50L6GT) and all of the Loktal tubes are labeled Philco.

Joseph


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 Post subject: Re: Loktal 7B7 with RCA label?
PostPosted: Aug Tue 09, 2022 10:12 pm 
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munali wrote:
...and all of the Loktal tubes are labeled Philco.

Joseph
And none of them were manufactured by Philco. It has been quite interesting over the years to see how tube manufacturers "cooperated" with each other.

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 Post subject: Re: Loktal 7B7 with RCA label?
PostPosted: Aug Tue 09, 2022 11:04 pm 
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None of them were made by Philco, but they sure loved using them.....probably more than any other manufacturer. My guess is that they got good deals on war surplus?

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 Post subject: Re: Loktal 7B7 with RCA label?
PostPosted: Aug Wed 10, 2022 3:52 am 
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tubes4life wrote:
None of them were made by Philco, but they sure loved using them.....probably more than any other manufacturer. My guess is that they got good deals on war surplus?


Philco and Sylvania worked together to develop the loktal tube shortly after RCA/GE's metal tubes came out, and Philco started rolling them out in their 1940 sets (after apparently spending 1939 burning through what looks like the country's remaining supply of pre-octals :mrgreen:). Anyone who was getting their tubes from Sylvania could have used loktals but AFAIK it was almost all Philco with lots of Silvertones, and a handful of them in Zeniths and some others.

Sylvania was probably pretty motivated to continue to get some use out of the tooling after the war was over and kept supplying them until the miniatures couldn't be ignored anymore.


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 Post subject: Re: Loktal 7B7 with RCA label?
PostPosted: Aug Thu 11, 2022 4:55 am 
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Some say the locking center pin came about as a safety measure for wartime radio.
Here's a pretty good ad from that prewar era.


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Sylvania ad.jpg
Sylvania ad.jpg [ 557.69 KiB | Viewed 121 times ]

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 Post subject: Re: Loktal 7B7 with RCA label?
PostPosted: Aug Thu 11, 2022 9:58 am 
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For military gear, they made sense---as someone that's struggled with removing loktals over the years, I can testify that there was no way they were falling out :lol:

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 Post subject: Re: Loktal 7B7 with RCA label?
PostPosted: Aug Thu 11, 2022 6:06 pm 
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Location: Orlando, FL
The loktal tube was invented for automobile radios. Sylvania patented the base, as well as the button stem construction.

RCA did briefly flirt with their rare lines of metal loktals (eg 7B5LM) and glass loktals (eg 35Z3LT). Both of these lines used what RCA called their "octalox" base. Such tubes have a bottom wafer base with tiny wires soldered into the pins. This differs from the Sylvania button stem base where the pins actually are part of the internal structure. Apparently the octalox base was expensive to make, so RCA gave up. They decided to buy loktals, instead of paying patent royalties.

GE's single entry in the field was their rare metal 12B7.

I know of only two other companies besides Sylvania that for sure made loktals in the US. National Union registered types 3C6, 7AF7, 7X7, and 14X7, and also was the single maker of the unregistered type 7D4. Raytheon registered types 7B5, 7B6, 7B8, 7C5, 7H7, 7K7, 7Q7, and 7T7.


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