Chinese 572B tubes and RF Parts
J. Aaron Holmes, Sat Mar 03 2007, 08:44AM!grr
Well, I suppose the end of this story can be guessed from the title, but I'll admit I'm still having a hard time believing it. Anyway, I ordered a matched trio of Chinese-made 572B tubes from RF Parts, as they seemed like good "beginner" tubes to play with (intended on using two and keeping one for a backup). Anyway, they got here today, and straight out of the box I found a number of problems: One tube had a very significant crack around the grid lead seal in the base. It was very plain to see, and were it not for the metal it was wrapped around, a large piece of glass would probably have been jingling around in the bottom of the tube. A second tube had a misaligned metal plate on one of the grid posts that was so far bent down that it was within an eighth of an inch of the tube plate. Seemed like a great place for arcing. I'll have to dig out the camera and take some good photos of these, but they just look like j-u-n-k, period.In any event, the tubes will be heading back to RF Parts next week. I haven't decided whether I'll bless them with my business again, or if I'll take my business of replacing the tubes to somebody else. If I bother to pay for new tubes again, I'll probably buy the Svetlana 572B's or go NOS on eBay.
So there you have it. Think twice about buying Chinese-made tubes, or at least the Sino/Shuguang 572B's. I know some of you have used the Chinese "Taylor" 833-A and -C tubes without trouble, though. I guess they must be ok.
Grumble, grumble...
Aaron, N7OE
Re: Chinese 572B tubes and RF Parts
Sulaiman, Sat Mar 03 2007, 11:21AM
Could it be that the breakage and internal mis-alignment are due postal damage?
If subject to impact the internal parts could have moved.
(I have seen equipment that looks perfect on the outside with major internal damage due to shipping mis-handling)
Sulaiman, Sat Mar 03 2007, 11:21AM
Could it be that the breakage and internal mis-alignment are due postal damage?
If subject to impact the internal parts could have moved.
(I have seen equipment that looks perfect on the outside with major internal damage due to shipping mis-handling)
Re: Chinese 572B tubes and RF Parts
Dr. Drone, Sat Mar 03 2007, 04:18PM
Dr. Drone, Sat Mar 03 2007, 04:18PM
Re: Chinese 572B tubes and RF Parts
J. Aaron Holmes, Sat Mar 03 2007, 06:09PM
I suppose it's possible that the cracked grid lead seal could have been shipping-related, but it's only the inside half of the seal that's cracked, so it's pretty wierd. The tilted metal on the grid support is welded in place. It was almost certainly that way straight from the factory. That is the one that bothers me the most.
These pictures turned out HORRIBLE. Positively awful. But they'll give some idea of what I'm talking about. I really should have used my video camera instead, since it seems to be able to focus at much smaller distances:
http://silicon-arcana.com/tubes/cracked_grid_lead_seal.jpg
http://silicon-arcana.com/tubes/bad_grid_post_plate.jpg
I read the Chinese tube reviews on eHam.net before buying these, and felt pretty good about ordering them. There aren't any reviews of the 833's on there, but the 3-500Z and 572B clones scored well. I actually have a Chinese-made 3-500Z clone, and it looks as good as any Eimac tube I've ever seen. The 572B's just look like a lot of corner-cutting was taken at the factory. I'm not impressed at all by their appearance. I'm totally willing to believe other Chinese tubes are different though.
It's a bummer, as I'd pretty much gathered everything else needed to make a nice 572B coil, so I probably will go ahead and get the Svetlanas or find something NOS.
Regards,
Aaron, N7OE
J. Aaron Holmes, Sat Mar 03 2007, 06:09PM
I suppose it's possible that the cracked grid lead seal could have been shipping-related, but it's only the inside half of the seal that's cracked, so it's pretty wierd. The tilted metal on the grid support is welded in place. It was almost certainly that way straight from the factory. That is the one that bothers me the most.
These pictures turned out HORRIBLE. Positively awful. But they'll give some idea of what I'm talking about. I really should have used my video camera instead, since it seems to be able to focus at much smaller distances:
http://silicon-arcana.com/tubes/cracked_grid_lead_seal.jpg
http://silicon-arcana.com/tubes/bad_grid_post_plate.jpg
I read the Chinese tube reviews on eHam.net before buying these, and felt pretty good about ordering them. There aren't any reviews of the 833's on there, but the 3-500Z and 572B clones scored well. I actually have a Chinese-made 3-500Z clone, and it looks as good as any Eimac tube I've ever seen. The 572B's just look like a lot of corner-cutting was taken at the factory. I'm not impressed at all by their appearance. I'm totally willing to believe other Chinese tubes are different though.
It's a bummer, as I'd pretty much gathered everything else needed to make a nice 572B coil, so I probably will go ahead and get the Svetlanas or find something NOS.
Regards,
Aaron, N7OE
Re: Chinese 572B tubes and RF Parts
Terry Fritz, Sun Mar 04 2007, 02:38AM
Hi,
If you think they just look bad, for goodness sake don't plug them in or you will "really" find out how bad they are!
My tube coil came with Chinese tubes (811). After I glued both top caps back on and also glued one back into the base (they "rattled apart" in the mail
) they lasted about 15 seconds... One had two internal wires to the pins miss routed too close and shorted with a dramatic bang... The other had a miss formed glass part in the base which probably would have failed in another 5 seconds. 
I replaced them with Svetlana types. The new Svetlana tubes are approximately 10,000,000 times better
Rock solid, very high quality, and zero problems...
So tell RFParts you want Svetlana "only"... Yes, they are the most expensive, but not too much more... I would have a hard time believing the Chinese tubes I have seen would ever run for any length of time and I doubt they are even tested... The quality is unbelievably poor... I don't even know why they bother to try to make tubes... A lot of stuff from China is really nice, but they don't do "tubes"... I almost doubt if they even know what they are supposed to be used for... It's like they made a cheap "visual" copy from a picture or something...
So just get the Svetlana and be happy. You won't need extras unless you break it or turn the coil up way too high... They should last forever...
Cheers
Terry
Terry Fritz, Sun Mar 04 2007, 02:38AM
Hi,
If you think they just look bad, for goodness sake don't plug them in or you will "really" find out how bad they are!
My tube coil came with Chinese tubes (811). After I glued both top caps back on and also glued one back into the base (they "rattled apart" in the mail
) they lasted about 15 seconds... One had two internal wires to the pins miss routed too close and shorted with a dramatic bang... The other had a miss formed glass part in the base which probably would have failed in another 5 seconds. I replaced them with Svetlana types. The new Svetlana tubes are approximately 10,000,000 times better
Rock solid, very high quality, and zero problems...So tell RFParts you want Svetlana "only"... Yes, they are the most expensive, but not too much more... I would have a hard time believing the Chinese tubes I have seen would ever run for any length of time and I doubt they are even tested... The quality is unbelievably poor... I don't even know why they bother to try to make tubes... A lot of stuff from China is really nice, but they don't do "tubes"... I almost doubt if they even know what they are supposed to be used for... It's like they made a cheap "visual" copy from a picture or something...
So just get the Svetlana and be happy. You won't need extras unless you break it or turn the coil up way too high... They should last forever...
Cheers
Terry
Re: Chinese 572B tubes and RF Parts
..., Sun Mar 04 2007, 02:58AM
I haven't really had any trouble with RF parts, but in general the chinese 811a tubes are crap compared to the nos design. The biggest problem I have is with the internal wire that goes to the gird gets close to the filament and then arks over... But in general the plates can only handle a fraction of the power a 'real; 811a can.
"You get what you pay for"
..., Sun Mar 04 2007, 02:58AM
I haven't really had any trouble with RF parts, but in general the chinese 811a tubes are crap compared to the nos design. The biggest problem I have is with the internal wire that goes to the gird gets close to the filament and then arks over... But in general the plates can only handle a fraction of the power a 'real; 811a can.
"You get what you pay for"
Re: Chinese 572B tubes and RF Parts
J. Aaron Holmes, Sun Mar 04 2007, 03:01AM
Hehehhehe... Terry, your reply makes getting busted tubes almost worth it
LOL!! "Cheap visual copy from a photo". I love it! I think the quality definitely varies though, as I have a Chinese 3-500ZG that looks fantastic (rebranded "RF Parts", although I got it at a flea market). That particular Chinese tube has rated well on various ham sites, too. But from what I've lately read, it seems the Chinese have been making some of these tubes a lot longer than others. The 572B appears to be a relatively "new" thing. Still, just the look of these is pretty inexcusable. I suppose the most disappointing thing is that RF Parts would sell them, since they're generally regarded as a pretty good business.
A coworker of mine built a VTTC a few years ago using two of the Svetlana 572B's. Despite that hams love to complain about them because they're electrically different from the Taylor clones, he runs them with a level-shifted MOT and they haven't flashed over; they're seeing like 15kV from the tank ringing and they're only rated for 2.5kV! I was pretty impressed. Stupid me for not just buying a pair of *those*.
I'm torn now between the desire to complete my 572B-based design and the desire to get some 3-500 and 3-1000 sockets. The 3-1000Z sitting on my desk has the most wonderfully symmetrical structure inside, its draw has increased substantially after seeing these Chinese 572B's. Yikes!! Still, I could buy a nice pair of Svetlana 572B's or I could spend the same money on a 3-1000 socket, so probably I'd be stupid to do the latter) (but I've done stupider things before, like what this thread is about...)
Regards,
Aaron, N7OE
J. Aaron Holmes, Sun Mar 04 2007, 03:01AM
Hehehhehe... Terry, your reply makes getting busted tubes almost worth it
LOL!! "Cheap visual copy from a photo". I love it! I think the quality definitely varies though, as I have a Chinese 3-500ZG that looks fantastic (rebranded "RF Parts", although I got it at a flea market). That particular Chinese tube has rated well on various ham sites, too. But from what I've lately read, it seems the Chinese have been making some of these tubes a lot longer than others. The 572B appears to be a relatively "new" thing. Still, just the look of these is pretty inexcusable. I suppose the most disappointing thing is that RF Parts would sell them, since they're generally regarded as a pretty good business.A coworker of mine built a VTTC a few years ago using two of the Svetlana 572B's. Despite that hams love to complain about them because they're electrically different from the Taylor clones, he runs them with a level-shifted MOT and they haven't flashed over; they're seeing like 15kV from the tank ringing and they're only rated for 2.5kV! I was pretty impressed. Stupid me for not just buying a pair of *those*.
I'm torn now between the desire to complete my 572B-based design and the desire to get some 3-500 and 3-1000 sockets. The 3-1000Z sitting on my desk has the most wonderfully symmetrical structure inside, its draw has increased substantially after seeing these Chinese 572B's. Yikes!! Still, I could buy a nice pair of Svetlana 572B's or I could spend the same money on a 3-1000 socket, so probably I'd be stupid to do the latter
) (but I've done stupider things before, like what this thread is about...)Regards,
Aaron, N7OE
Re: Chinese 572B tubes and RF Parts
Steve Conner, Sun Mar 04 2007, 11:43AM
I like to play with tube audio. I've bought quite a few Russian military tubes, and even some brand new Russian designs specially for audio, but I've not tried Chinese tubes, and I wouldn't really care to either, from what I've heard. The Russian stuff seems to be pretty good.
Another interesting tube maker is JJ, started by a guy who bought out the old Tesla tube plant in the Czech Republic. He has a great reputation for quality. I think he only makes smallish audio tubes though.
Speaking of which, maybe those Chinese 572Bs were made for audiophool duty
They only need to be visual clones, since tubes always sound about as good as they look :P
There's a guy over here who brings a tube coil powered by a Svetlana 572B to most of the teslathons. I've seen him smoke a lot of components on it, but never the tube.
I have a 4-400A with socket and filament transformer, pulled from an old induction heater, that I keep meaning to do "something" with :/
Steve Conner, Sun Mar 04 2007, 11:43AM
I like to play with tube audio. I've bought quite a few Russian military tubes, and even some brand new Russian designs specially for audio, but I've not tried Chinese tubes, and I wouldn't really care to either, from what I've heard. The Russian stuff seems to be pretty good.
Another interesting tube maker is JJ, started by a guy who bought out the old Tesla tube plant in the Czech Republic. He has a great reputation for quality. I think he only makes smallish audio tubes though.
Speaking of which, maybe those Chinese 572Bs were made for audiophool duty
They only need to be visual clones, since tubes always sound about as good as they look :PThere's a guy over here who brings a tube coil powered by a Svetlana 572B to most of the teslathons. I've seen him smoke a lot of components on it, but never the tube.
I have a 4-400A with socket and filament transformer, pulled from an old induction heater, that I keep meaning to do "something" with :/
Re: Chinese 572B tubes and RF Parts
J. Aaron Holmes, Sun Mar 04 2007, 10:26PM
Yeah, nothing too big listed on the web page. You could probably get a spark by sticking boatloads of those ~450V tubes in parallel, though Call it a "MMT" (Multi Mini Tube) coil 
A "hollow state" relative of the OLTC. OLVTTC? At 5V on the filament, you could just series 48 of them to avoid the need for a filament transformer, hehehehehehhh...
EDIT: In fact, THIS should be a contest: Who can get *any* sparks from an OLVTTC (48 300B's with filaments in series and plates in parallel would have to do *something*, I think!)
Regards,
Aaron, N7OE
J. Aaron Holmes, Sun Mar 04 2007, 10:26PM
Steve Conner wrote ...
Another interesting tube maker is JJ, started by a guy who bought out the old Tesla tube plant in the Czech Republic. He has a great reputation for quality. I think he only makes smallish audio tubes though.
Another interesting tube maker is JJ, started by a guy who bought out the old Tesla tube plant in the Czech Republic. He has a great reputation for quality. I think he only makes smallish audio tubes though.
Yeah, nothing too big listed on the web page. You could probably get a spark by sticking boatloads of those ~450V tubes in parallel, though
Call it a "MMT" (Multi Mini Tube) coil A "hollow state" relative of the OLTC. OLVTTC? At 5V on the filament, you could just series 48 of them to avoid the need for a filament transformer, hehehehehehhh...EDIT: In fact, THIS should be a contest: Who can get *any* sparks from an OLVTTC
(48 300B's with filaments in series and plates in parallel would have to do *something*, I think!)Regards,
Aaron, N7OE
Re: Chinese 572B tubes and RF Parts
J. Aaron Holmes, Mon Mar 05 2007, 08:13PM
(Followup - sorry for the double-post)
I talked to a guy at RF Parts this morning. He seemed eager to remedy any issue I had with the tubes, which was nice. Also, he confessed, they actually hadn't sent me a matched set despite my having ordered one. Doh!
I told him I blamed their online ordering system, which is pretty ambiguous in its treatment of matched parts. Basically, I could specify either "3 matched 572B's", or "1 572B-M3", since they have part numbers for the matched sets, yet they also have a "Matched" checkbox on the order form next to the quantity field. Wierd. Since their ordering example used the former approach, that's what I did, however now you may all learn from my experience
In exchange for my trouble, I was offered an "upgrade" to the Taylor-branded tubes, which the guy insisted had a great reputation and were not only more aesthetically-pleasing, but also more rigorously hi-pot tested. Basically, they're the "top pick" Chinese tubes and come from a different factory. Hmmm... The other thing he told me was that the Svetlana 572B's were out of production, and would soon be gone forever
...so I'm not sure what I'll do. The tubes I ordered are on their way back. Now I'm torn between the desire to get the Svetlanas and own a bit of history (for about $60 more for the set) and the desire to validate the use of a current-production tube in a VTTC. What to do, what to do? The latter would seem to have more value for the VTTC'ing community, however I'm not especially eager to go through this again. Hmmm...
Regards,
Aaron, N7OE
J. Aaron Holmes, Mon Mar 05 2007, 08:13PM
(Followup - sorry for the double-post)
I talked to a guy at RF Parts this morning. He seemed eager to remedy any issue I had with the tubes, which was nice. Also, he confessed, they actually hadn't sent me a matched set despite my having ordered one. Doh!
I told him I blamed their online ordering system, which is pretty ambiguous in its treatment of matched parts. Basically, I could specify either "3 matched 572B's", or "1 572B-M3", since they have part numbers for the matched sets, yet they also have a "Matched" checkbox on the order form next to the quantity field. Wierd. Since their ordering example used the former approach, that's what I did, however now you may all learn from my experience In exchange for my trouble, I was offered an "upgrade" to the Taylor-branded tubes, which the guy insisted had a great reputation and were not only more aesthetically-pleasing, but also more rigorously hi-pot tested. Basically, they're the "top pick" Chinese tubes and come from a different factory. Hmmm... The other thing he told me was that the Svetlana 572B's were out of production, and would soon be gone forever
...so I'm not sure what I'll do. The tubes I ordered are on their way back. Now I'm torn between the desire to get the Svetlanas and own a bit of history (for about $60 more for the set) and the desire to validate the use of a current-production tube in a VTTC. What to do, what to do? The latter would seem to have more value for the VTTC'ing community, however I'm not especially eager to go through this again. Hmmm...
Regards,
Aaron, N7OE
Re: Chinese 572B tubes and RF Parts
Steve Ward, Mon Mar 05 2007, 11:15PM
Taylors always seemed to suit my needs. But if it really matters to you, get the svetlanas... but i probably wouldnt spend the money on them.
Steve Ward, Mon Mar 05 2007, 11:15PM
Taylors always seemed to suit my needs. But if it really matters to you, get the svetlanas... but i probably wouldnt spend the money on them.
Re: Chinese 572B tubes and RF Parts
Steve Conner, Tue Mar 06 2007, 12:24AM
I heard the 572B was never that great a RF tube anyway. Apparently it suffers badly from parasitics because the filament structure resonates at some fairly low RF frequency. I've seen people take RF amps that used to run 572Bs and perform major surgery to make them take different tubes. Anyway, my 4-400A says hi.
Steve Conner, Tue Mar 06 2007, 12:24AM
I heard the 572B was never that great a RF tube anyway. Apparently it suffers badly from parasitics because the filament structure resonates at some fairly low RF frequency. I've seen people take RF amps that used to run 572Bs and perform major surgery to make them take different tubes. Anyway, my 4-400A says hi.
Re: Chinese 572B tubes and RF Parts
J. Aaron Holmes, Tue Mar 06 2007, 06:07AM
Hmmm...you're making me wonder if I ought to mess with them (the 572B's) at all. Maybe I should just get what I need to run the 3-500Z, or the 3-1000Z (below):
Amusingly, the plate structure in the 3-1000Z is similar in size to the 3-500 and -400. It seems to be just the glass that's gotten bigger!
My dilemma is that a "cheap" 3-1000Z socket is like $70 USD Would it be ok just to clamp some flattened copper tubing around the pins for a homebrew socket? Any chance of strange disagreements between the metals? I'm not sure what the pins are made of. A homebrew "chimney", I suppose, could just be some clear acrylic tubing. Then I have to figure out how to get 7.5V at 20A for the filament Nice part is, the 3-1000Z is rated 6kV on the plate, so it ought to stand up to some terrible VTTC abuse.
You need to hook that tube of yours up! I especially like the 3-400 and -500 tubes with those horizontal-vaned plates. They look like science fiction
Regards,
Aaron, N7OE
J. Aaron Holmes, Tue Mar 06 2007, 06:07AM
Hmmm...you're making me wonder if I ought to mess with them (the 572B's) at all. Maybe I should just get what I need to run the 3-500Z, or the 3-1000Z (below):
Amusingly, the plate structure in the 3-1000Z is similar in size to the 3-500 and -400. It seems to be just the glass that's gotten bigger!
My dilemma is that a "cheap" 3-1000Z socket is like $70 USD
Would it be ok just to clamp some flattened copper tubing around the pins for a homebrew socket? Any chance of strange disagreements between the metals? I'm not sure what the pins are made of. A homebrew "chimney", I suppose, could just be some clear acrylic tubing. Then I have to figure out how to get 7.5V at 20A for the filament Nice part is, the 3-1000Z is rated 6kV on the plate, so it ought to stand up to some terrible VTTC abuse.You need to hook that tube of yours up! I especially like the 3-400 and -500 tubes with those horizontal-vaned plates. They look like science fiction
Regards,
Aaron, N7OE
Re: Chinese 572B tubes and RF Parts
Steve Ward, Tue Mar 06 2007, 08:28PM
Or, just get an 833C and socket (150 bucks total, new from RF parts) and call it done.
Steve Ward, Tue Mar 06 2007, 08:28PM
Or, just get an 833C and socket (150 bucks total, new from RF parts) and call it done.
Re: Chinese 572B tubes and RF Parts
Steve Conner, Tue Mar 06 2007, 09:46PM
Meh, if he gets a socket for his 3-1000Z, it's done for 70 bucks :P Or I don't see any reason not to make the socket yourself. The secret (AFAIK) is not to bolt the contacts down tight to whatever base you choose, you need to leave a bit of slop to let things expand with heat, otherwise you'll crack the tube.
yikes!
Steve Conner, Tue Mar 06 2007, 09:46PM
Meh, if he gets a socket for his 3-1000Z, it's done for 70 bucks :P Or I don't see any reason not to make the socket yourself. The secret (AFAIK) is not to bolt the contacts down tight to whatever base you choose, you need to leave a bit of slop to let things expand with heat, otherwise you'll crack the tube.
yikes!
Re: Chinese 572B tubes and RF Parts
J. Aaron Holmes, Tue Mar 06 2007, 10:41PM
Aaahhhhhhhh...that is a beautiful sight!
To answer Steve W.'s implied question of why I don't just go get an 833C: Because there are a lot of 833A/C coils now, and by picking something much less usual (or at least less-documented, as VTTC use goes), I'll force myself to fiddle and understand a lot more before anything works. That is the only way I predict getting any enjoyment from the project. Otherwise, it'll all be over with too quickly and I'll have just "copied". Maybe that's a lame reason, but it works for me!
Regards,
Aaron, N7OE
J. Aaron Holmes, Tue Mar 06 2007, 10:41PM
Aaahhhhhhhh...that is a beautiful sight!
To answer Steve W.'s implied question of why I don't just go get an 833C: Because there are a lot of 833A/C coils now, and by picking something much less usual (or at least less-documented, as VTTC use goes), I'll force myself to fiddle and understand a lot more before anything works. That is the only way I predict getting any enjoyment from the project. Otherwise, it'll all be over with too quickly and I'll have just "copied". Maybe that's a lame reason, but it works for me!
Regards,
Aaron, N7OE
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