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SWEEP TUBES: Which brand works best for RF ??

unit_399

unit_399

EL CAPO
Jun 17, 2008
2,124
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ALEJANDRIA, COLOMBIA SA
I was reading a post about tube amps, and got to wondering about something. When I ran a tube amp in my setup (back in the 70s), I always used Sylvania tubes, mostly 6LQ6s. The word back then was that Sylvania tubes worked best for RF. Most said that GE tubes didn't last long because their plate structure couldn't handle vibrating at 27mhz (???).

Tubes were CHEAP then. Whenever the power in the amp dropped off, I just bought a new set.

Down here, there is a LOT of old tube equipment (mostly TVs) still in service. There used to be quite a few shops that worked on tube stuff, but many of the old techs have passed and their stores shut down.

I picked up a Kris "BIG BOOMER" amp a while back ( price was right), but it's just set on the shelf. If I ever get to looking at it, I want to have a new set of tubes, so I figured I'd go buy a couple of sets while they're still available at reasonable prices. I called around, and NOS RCA, GE, Sylvania, Raytheon (even some Philco) 6LQ6s are available.

So ... What do you guys ( Hey, NOMAD! ) think ?? What brand is best for rf amps ?? And why.

- 399
 

Sylvania and rca had real good tubes. And to break the news to ya, all the tubes were made by the same manufacturers and then branded. Slightly different build specs but thats it. There where only a hand full of valve manufacturers back in the day and only a couple left now. Nobody could beat russia and Ukraine built tubes. The best really. Anyway just pick the newest ones you can get and roll with it. They are television sweep tubes after all, your not gonna find a solid hd tube. They are not made for rf service
 
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groundwire said:
Sylvania and rca had real good tubes. And to break the news to ya, all the tubes were made by the same manufacturers and then branded. Slightly different build specs but thats it. There where only a hand full of valve manufacturers back in the day and only a couple left now. Nobody could beat russia and Ukraine built tubes. The best really. Anyway just pick the newest ones you can get and roll with it. They are television sweep tubes after all, your not gonna find a solid hd tube. They are not made for rf service
Click to expand...
Didn't D&A have their own branded tubes and I was told a rumor that they had a stouter grid structure or something?
 
groundwire said:
Sylvania and rca had real good tubes. And to break the news to ya, all the tubes were made by the same manufacturers and then branded. Slightly different build specs but thats it.
Click to expand...
What you say about the same manufacturer may be true, but the "slightly different" build specs ... not so much.

- 399

6LQ6SYLUntitled.png


6LQ6GEUntitled.png


6LQ6 RAY.png


6LQ6 RCA.png
 
You don't really know who made a tube until you can get a detailed look at it. The brightly-colored brand name and logo are not applied to the tube on the assembly line. Just the indelible (you hope) type number, maybe a date and/or batch code.

The factories would ship the blank tubes in egg-crate cartons of one gross, 12 rows of 12 columns.

Every company that owned a factory also had a sales division. Kinda like car companies. You don't buy a car directly from the factory. It still has to come by way of a sales representative of some kind. Even if you buy a fleet, it goes through a sales division that's not part of the factory.

Same deal with tubes. A separate business unit prints your brand name on the tubes from your factory and on the individual sales cartons that hold just one tube. But what do you do when your warehouse stock runs out? If the factory had that type number scheduled to make them in time you get them from your own factory and your customers are happy.

If they tell you it's gonna be six weeks before the next batch of 6L6GC tubes you buy them on the open market, kinda like crude oil. A broker finds those unbranded bulk tubes from some other factory. You print your name on them, and on the cartons you pack them into. You fill the orders your distributors placed with you and all is well. A sales company doesn't make money by telling customers to wait six weeks.

This is where that connection gets broken, between the maker of a tube and the brand name printed on it.

Some brands continued their sales divisions years after closing their tube factory. Raytheon is a company that still exists, even though it hasn't sold a consumer product of any kind in decades. When their tube factory closed up, their sales division carried on for years, printing that name on tubes made by someone, anyone else.

Long after Westinghouse had made their last tube, their name and logo would still appear on cartons and tubes sold by a company called Elmira Electronics. They were strictly a sales outfit, located strangely enough in Elmira New York. This was a license deal of some sort, to use the Westinghouse name on stuff that had nothing to do with that company.

D&A took advantage of a promotion tool that other folks have used. If you buy enough of an item, they'll print whatever name and part number you like on it. The D&A "D50" tubes were 6MJ6 upgraded sweep tubes. Not sure who the source was.

The collection of type numbers on the tube in the pics above is a whole separate story of upgrades and lawsuits.

For another day.

73
 
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Idk much about brands but if you have the coin you can try tubedepot.com, they are based out of Memphis. I use them for tubes and hv caps every time I get a tube-type "foot warmer".
 
Western Electric is back in business making tubes. Supposedly, some time this Summer they are supposed to be making popular in demand tubes right here in the USA. Story linked down below. And they have a website too.


www.westernelectric.com

Western Electric - Maker of electron tubes and high fidelity

Maker of electron tubes and high fidelity. Founded in 1869, we're an American manufacturer with an enduring relationship with quality. Today, we make stunning listening experiences through innovative audio equipment and legacy hi-fi like the 300B vacuum tube.
www.westernelectric.com www.westernelectric.com

www.wired.com

One Man’s Quest to Revive the Great American Vacuum Tube

The prized retro audio components are mostly manufactured in Russia and China. Now, a small Georgia company is rebooting US production.
www.wired.com www.wired.com
 
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I wrote to Western Electric the beginning of this year, they are only building 300B audio Tubes.
When I asked about building Sweep tubes I got a reply that they are only making the 300 audio tubes and at this time they do not plan making anything other than Audio Tubes, no Sweep tubes......
The price of the 300b says a lot.
Although you do get a nice wooden box .

73
Jeff
 
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Television sweep tubes are over. Nobody in thier right mind would make those things. Useless! There is 100% no market for them. Tubes in general are almost dead. The only people keeping the last few tube manufacturers alive is the music instrument/audiophile crowd. Radio equipment only acounts for about 10% of the market. Ham radio and the broadcast industry is not keeping tube makers afloat, as they wish to believe.
 
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groundwire said:
Television sweep tubes are over. Nobody in thier right mind would make those things. Useless! There is 100% no market for them. Tubes in general are almost dead. The only people keeping the last few tube manufacturers alive is the music instrument/audiophile crowd. Radio equipment only acounts for about 10% of the market. Ham radio and the broadcast industry is not keeping tube makers afloat, as they wish to believe.
Click to expand...
This is true, realistically speaking, there's only a couple part numbers that are actually getting produced in any appreciable quantities.

811a, 572b, 3-500z, 3cx1500a7, 3cx3000a7. Everything else is built one at a time if at all. People have this idea that there's this multitude of tubes to build with, but if you're talking about actual new production and not surplus, there's not really.
Also, everybody seems to think that if you have enough money you can just get whatever you want made. It doesn't really work that way. I recently was able to get a really, really, really large triode that most people have no business purchasing. I was able to get a factory to produce it for me. Brand new without a core. I sure paid for it though.
And I'll be honest ,I was very fortunate to get it.
 
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