Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: mresistor on January 27, 2016, 02:58:30 pm
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I received an Amperex 5Y3GT rectifier in a lot of tubes. And it is different than most 5Y3GT's I have. It only has 4 pins. It says it is made in England. Now when I test it on my old heathkit TC-2 tester it pegs the needle to the good. When I lower the plate voltage on the tester the needle comes back down into green territory on the meter. Anyone have any info on these tubes? Here's a pic.
http://i122.photobucket.com/albums/o250/privateacct/004_zpsvfkkmssr.jpg (http://i122.photobucket.com/albums/o250/privateacct/004_zpsvfkkmssr.jpg)
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Looks and acts like a brand new tube, doesn't it?
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That's what I was thinking. I've never had a brand new 5Y3GT, only used ones so I haven't seen this before.
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That's a Russian-made tube with 5Y3-like specs. It is no different than any other new production "5Y3" tube which exhibits less voltage drop than a vintage 5Y3.
The "Made in England" and "Amperex" labels are fakes. I've got Russki 6L6 type tubes which are screened "RCA" and "Made in England" but are very obviously Sovtek tubes.
FWIW, I don't believe any Brit companies ever screened "Made in England" on their tubes sold in the U.S.; they always say (to my knowledge) "Made in Gt. Britain".
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Thanks HPB. I suspected something different about this tube. I thought Amperex was made in Holland?
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> I thought Amperex was made in Holland?
Brooklyn?
Ah, Philips bought them in 1955, but much production still happened in New York. As Philips also made bottles ALL over Europe, and bought-in some types to fill the catalog, only a geek will know.
If you have any clue your tube is not old-old, then it is Russian or Chinese. USSR made millions of rectifiers easily re-painted with the type, brand, and country of your choice.
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That's a Russian-made tube with 5Y3-like specs. It is no different than any other new production "5Y3" tube which exhibits less voltage drop than a vintage 5Y3.
The "Made in England" and "Amperex" labels are fakes. I've got Russki 6L6 type tubes which are screened "RCA" and "Made in England" but are very obviously Sovtek tubes.
FWIW, I don't believe any Brit companies ever screened "Made in England" on their tubes sold in the U.S.; they always say (to my knowledge) "Made in Gt. Britain".
I would say that 95+% of the Mullard tubes I have say "Made in Gt. Britain".
But then I do have these Mullards which came out of early 1960's HP lab gear that say "Made in England".
I am pretty confident that at that time HP didn't source their tubes with the cheapest Chinese/Russian knock offs they could buy. :dontknow:
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I would say that 95+% of the Mullard tubes I have say "Made in Gt. Britain".
But then I do have these Mullards which came out of early 1960's HP lab gear that say "Made in England".
Interesting! It would be worthwhile to look for the Philips codes on the glass of those tubes, to sort out if Mullard actually made those, or if it was some other maker under the Philips umbrella.
In any case, compare the plate structure and mica spacers in the original picture with the tubes below. The first has a faintly-visible "USSR" in the lower-middle of the glass envelope (it's an older Sovtek), while the other has "OTK" on the base which is a Russian marking.
(http://www.cryoset.com/catalog/images/5y3sbruss.jpg)
(http://acimg.auctivacommerce.com/imgdata/0/1/2/8/8/9/webimg/4624373.jpg)
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The only code I could find on the glass is BH.
I could not find any other markings on the base or anywhere else. :dontknow:
But these Mullards do have the pinched top marks! :icon_biggrin: