What tube is this?

[SLW]

I was going through the old tubes I have collected.  This one has no ID markings on it.  It looks like a rectifier but I don't know.  Perhaps one of you more experienced guys can identify it.  The only numbers on it are 65-52.  I assume that this a date code.  There are 5 pins on the base.

SLW

[RicharD]

Looks like a 5Y3.  It's certainly a rectifier tube.  52nd week of 1965. 

[eleventeen]

99% certain it's a 5Y3. 5 pin base = absolutely a rectifier. Twin plate structure looks exactly like a 5Y3.

Too lazy to photgraph one sitting on my desk.........

http://cgi.ebay.com/RCA-5Y3GT-5Y3-black-plate-D-getter-rectifier-tubes-NIB-/120586920822?cmd=ViewItem&pt=Vintage_Electronics_R2&hash=item1c138a6376

http://cgi.ebay.com/RCA-5Y3GT-5Y3-GT-AUDIO-AMPLIFIER-RECTIFIER-TUBE-PAIR-/380247032251?cmd=ViewItem&pt=Vintage_Electronics_R2&hash=item58887d41bb

http://cgi.ebay.com/Pair-NOS-RCA-5Y3-GT-Tubes-/360273570460?cmd=ViewItem&pt=Vintage_Electronics_R2&hash=item53e1fa6a9c

http://cgi.ebay.com/VINTAGE-TUBE-RCA-5Y3-GT-TESTED-STRONG-/360277261520?cmd=ViewItem&pt=Vintage_Electronics_R2&hash=item53e232bcd0  <<<< prob the best comparison pix for your purposes.

[HotBluePlates]

3rd opinion concurs with the first 2. It's a 5Y3.

As an aside, many american manufacturers made tubes for each other to meet orders. This tube is what it claims to be (RCA 5Y3), based on the limited marking present and construction style.

[SLW]

Thanks guys.  I knew the forum would help me out.  It looks like it has never been used.  A lot of the tubes I collect look new.  As you may (or may not know) I work at a University.  Whenever somebody cleans out a lab or office I end up with tubes.  The highlights of the collection are a pair of new 6V6GT's from 54 (marked GE), a pair of used Sylvania 6L6's, some 12AX7s and 12AT7's.  Lots of other tubes too like Amperex 6DJ8's and others that I have not looked up yet.  Some manufacturers I have not heard of before and a few really old looking ones.  There is a delay relay tube that looks really cool.

SLW

[HotBluePlates]

... a pair of new 6V6GT's from 54 (marked GE) ...

Look for a code number stamped on the base. If you see "188-something" then it was indeed made by G.E.

There is a delay relay tube that looks really cool.

Really not a tube, but those relays often had octal bases. I might have 1 or 2 floating around somewhere.

[bluesbear]

Here's an odd story about collecting tubes from work. I'm retired from the federal govt where I was in building maintenance. Many years ago, they were cleaning out the stockroom. There were some NOS boxes of Mullard 6V6's. OF course, these never hit the dumpster! Later, I found out that Mullard never made 6V6's and these were fakes made in the Soviet Union. My question was, "Why were there fake Soviet made tubes from the '60's in a US govt facility?" Seems odd, to say the least!
On a related note: I came back after my off day and found an old Shure green bullit, still on the "highway patrol" stand. I was thrilled until I found out they'd thrown away 19 of them the day before and the dumpster had been emptied. Keep in mind, this was before the reissues had come out. It was a sad day!
Dave

[HotBluePlates]

Later, I found out that Mullard never made 6V6's and these were fakes made in the Soviet Union. My question was, "Why were there fake Soviet made tubes from the '60's in a US govt facility?"

Are you sure they were russian?

I've seen some pretty old (meaning 70's-80's) russian tubes remarked as european brands. My unsupported opinion is that some distributor had a supply of russian tubes cheap, and wanted to offload them in the U.S. for a fair profit. But the U.S. in the middle of the cold war seems like an unlikely place to sell soviet-made stuff. I have a feeling it was all about getting the profit that low-cost russian tubes would deliver, while fooling customs into not questioning them by marking the tubes as being european in origin.

[SLW]

... a pair of new 6V6GT's from 54 (marked GE) ...

Look for a code number stamped on the base. If you see "188-something" then it was indeed made by G.E.

There is a delay relay tube that looks really cool.

Really not a tube, but those relays often had octal bases. I might have 1 or 2 floating around somewhere.

They are stamped 188-5.  I figured it was a factory code or something like that.  They have JAN-CG-6V6GT stamped on the base.  I believe that means they were made for the military.  The tubes have a black liner inside the tube that you can barely see through.  I have never seen that before.  What is it?

[eleventeen]

"The tubes have a black liner inside the tube that you can barely see through.  I have never seen that before.  What is it?"

My understanding is that it's a graphite coating that reduces stray electrons from doing whatever mischief they might do during operation. Some older 6SN7s and 6SL7s have this as well.

[HotBluePlates]

They have JAN-CG-6V6GT stamped on the base.

JAN stands for Joint Army-Navy. If the tube is old enough, it also has a 2-letter code indicating manufacturer. "CG" is for G.E. I think CR was RCA, CK was Ken-Rad, I forget what Raytheon's code was. Actually, I barely remember them at all. But regardless, the 50's-60's JAN tubes were marked that way. 70's and 80's JAN tubes were not, and it's one easy way to guess era if no date codes are present.

My understanding is that it's a graphite coating ...

My understanding was is was a form of shielding inside the tube's glass, taking the place of the metal envelope which provided shielding in the older metal tubes. But I'd have to look at an old reference to say for sure.