Datasheets:
http://frank.pocnet.net/sheets/084/6/6HJ5.pdf
http://frank.pocnet.net/sheets/084/6/6HD5.pdf (same tube except pinout, different Vg2 graph)
http://frank.pocnet.net/sheets/123/6/6LG6.pdf ( similar tube, more graphs)
1) 6HJ5 pentode
2) 6HJ5 g2 drive
3) 6HJ5 triode
4) 6HJ5 Schade
5) 21LG6 pentode
6) 12GE5 pentode
7) 6HJ5 graph at 160 Vg2
http://frank.pocnet.net/sheets/084/6/6HJ5.pdf
http://frank.pocnet.net/sheets/084/6/6HD5.pdf (same tube except pinout, different Vg2 graph)
http://frank.pocnet.net/sheets/123/6/6LG6.pdf ( similar tube, more graphs)
1) 6HJ5 pentode
2) 6HJ5 g2 drive
3) 6HJ5 triode
4) 6HJ5 Schade
5) 21LG6 pentode
6) 12GE5 pentode
7) 6HJ5 graph at 160 Vg2
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I can't find them on that site😕 I actually don't think I am on the correct site but I went to the one you posted. vacuum-tubes.net.
I can find them for $6ea. But $4 is better. I figure who cares I am just going to buy some of them too. I should have a good supply of sweep tubes after this🙂
I just got to get some batteries for the camera and I can post some pics of the tubes I got.
Now what iron to buy
Here is the list on the site--
6C to 6LY8
Its about halfway down. Its nice to know they are actually in stock too, and at that price. With postage to me, it works out about £4 per valve, so not bad at all--Shipping is always the killer though!
6C to 6LY8
Its about halfway down. Its nice to know they are actually in stock too, and at that price. With postage to me, it works out about £4 per valve, so not bad at all--Shipping is always the killer though!
Well I don't eat that much meat, chicken maybe once every couple weeks. I haven't gone out to eat at all lately and pretty much just living off coffee, beans, and rice. Well of course some fruit and veggies too. But with the money I have saved to fulfill my addiction I just placed an order for 24 6HJ5's 🙂
Here are some pics of the 6AV5GA's I got. Four look to be the same type RCA. The other three appear to all be different variants. I can post better pics of the individual specimens if anyone is interested. I have not had the chance to do anything with them yet, I haven't even looked at the roll chart in my Hickok 539b for test settings. I have to see what kind of iron I have laying around too, I don't have much and will need to order some.
Here are some pics of the 6AV5GA's I got. Four look to be the same type RCA. The other three appear to all be different variants. I can post better pics of the individual specimens if anyone is interested. I have not had the chance to do anything with them yet, I haven't even looked at the roll chart in my Hickok 539b for test settings. I have to see what kind of iron I have laying around too, I don't have much and will need to order some.
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Looks like the Raytheon and Sylvania may be the original 6AV5GA guts. The RCAs look more like a 6GT5 than the 6GE5, with those big square holes. Pretty much the same thing anyway, just RCA's similar version of the 6GE5 it seems.
Would have to measure the plate size to see if they can handle more than 11 Watts. The 6GE5/6JN6 // 6GT5 have 1.25 inch between micas and a 1.25 inch wide plate. An older 12BQ6GA I have here measures 1.25 inch between micas, but 1.125 inch across the plate (and 1 inch from plate side holes to holes). (12GE5 is similarly 1 inch across holes to holes)
Hard to see why one would be rated 11 Watts and the other 17.5 Watts. The 6AV5GA is rated 210 deg. C for the glass. The 6GE5/6JN6 and 6BQ6GA are rated 220 deg. C glass, and the 6GT5A is rated 240 deg. C glass.
6HJ5 (24 Watt) has a 1.5 inch long plate and 240 deg. C glass.
Would have to measure the plate size to see if they can handle more than 11 Watts. The 6GE5/6JN6 // 6GT5 have 1.25 inch between micas and a 1.25 inch wide plate. An older 12BQ6GA I have here measures 1.25 inch between micas, but 1.125 inch across the plate (and 1 inch from plate side holes to holes). (12GE5 is similarly 1 inch across holes to holes)
Hard to see why one would be rated 11 Watts and the other 17.5 Watts. The 6AV5GA is rated 210 deg. C for the glass. The 6GE5/6JN6 and 6BQ6GA are rated 220 deg. C glass, and the 6GT5A is rated 240 deg. C glass.
6HJ5 (24 Watt) has a 1.5 inch long plate and 240 deg. C glass.
So I take it I didn't do that great. Maybe I can use them for low wattage guitar amps or something.
I still got the 6HJ5's coming hopefully they are the real deal.
I still got the 6HJ5's coming hopefully they are the real deal.
6HJ5 is sorta like a 'GE5 on steroids....
Maybe seeing the 'GE5 is like 2A3 when Trioded, then the 'HJ5 may be bit like 300B. Only spoiler is the Screen volts,--Wonder how much it will take in real life, DCV is only 220V according to data-sheet....
Ive ordered some 6HJ5, mainly to experiment for OTL but will probably try trioded see what it'll take...
Vacuumtubes.net have 'odd'/old-fashioned ordering format--You order by PP--Then they send Invoice,--then you pay, rather than building the order and paying straight away....
Currently waiting for invoice.......
Maybe seeing the 'GE5 is like 2A3 when Trioded, then the 'HJ5 may be bit like 300B. Only spoiler is the Screen volts,--Wonder how much it will take in real life, DCV is only 220V according to data-sheet....
Ive ordered some 6HJ5, mainly to experiment for OTL but will probably try trioded see what it'll take...
Vacuumtubes.net have 'odd'/old-fashioned ordering format--You order by PP--Then they send Invoice,--then you pay, rather than building the order and paying straight away....
Currently waiting for invoice.......
Be patient. I went through the whole procedure and my tubes arrived today🙂 After I sent payment they were very fast to ship. Packaged nicely as well.
Yes they are the Raytheon w/ black plates. Every Raytheon tube I have ever had with black plates has tested very strong and consistent and I usually like the results. Those guys know how to make tubes. I have a dozen or so black plate 12AX7's that test really high for transconductance and sound AMAZING in a guitar amp. I don't use any other tube for the first gain stage in my guitar amps anymore. I also have about 50 or so 6SN7GTB that have black plates. I noticed that every Raytheon tube I get the flashing always looks different then any other tube manufacturer.
Back to the 6HJ5. Here are some pictures. They appear to be made really well, doesn't surprise me from this company. I can't wait to try em out.
Yes they are the Raytheon w/ black plates. Every Raytheon tube I have ever had with black plates has tested very strong and consistent and I usually like the results. Those guys know how to make tubes. I have a dozen or so black plate 12AX7's that test really high for transconductance and sound AMAZING in a guitar amp. I don't use any other tube for the first gain stage in my guitar amps anymore. I also have about 50 or so 6SN7GTB that have black plates. I noticed that every Raytheon tube I get the flashing always looks different then any other tube manufacturer.
Back to the 6HJ5. Here are some pictures. They appear to be made really well, doesn't surprise me from this company. I can't wait to try em out.
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You are right--The invoice came an hour ago....
Looks Very nice, All yours look to be same batch--the 'DR' on the box....
At the mo, I could only afford 10 tubes, With shipping to UK, works out to $65. Still pounds to dollars, thats a $4 buck tube there, and a £4 quid tube shipped with current exchange-rate Good price Cant get a bag of fish and chips for £4 round here!....
We see what mine turn out like too--Be about a week--maybe more.....
Get testing! Wanna see what they can do!
Looks Very nice, All yours look to be same batch--the 'DR' on the box....
At the mo, I could only afford 10 tubes, With shipping to UK, works out to $65. Still pounds to dollars, thats a $4 buck tube there, and a £4 quid tube shipped with current exchange-rate Good price Cant get a bag of fish and chips for £4 round here!....
We see what mine turn out like too--Be about a week--maybe more.....
Get testing! Wanna see what they can do!
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Thanks again for giving me the heads up on those tubes. 
I am glad I didn't miss out.
I wonder if tubelab did any triode strapped SE testing with the 6HJ5. I think he said he was going on a road trip. He got the lab up and running, even blew up some Mosfets last week. He tends to like to push things much harder than I do. "He eats sweep tubes for breakfast" I think I remember reading someone say
I am glad I didn't miss out.
I wonder if tubelab did any triode strapped SE testing with the 6HJ5. I think he said he was going on a road trip. He got the lab up and running, even blew up some Mosfets last week. He tends to like to push things much harder than I do. "He eats sweep tubes for breakfast" I think I remember reading someone say
Looks like you got some nice tubes there. I think George got around 120 Watts or so, max, out of 6HJ5s in P-P. But then settled on 75 Watts max for his home setup. (more class A into the class AB operation I guess) These tubes can certainly handle a 60 Watt or 100 Watt Edcor P-P OT. (3.3K or 4K primary, depending on B+ available)
I just tried a 6HJ5 on the curve tracer here in triode mode with HV on the "plate+g2". I can get up to 1000V without any flashovers. I don't think I would want to rely on that for extended operation though. The 6HJ5 has got 2.8x the current capability, 2x the gm, and 1/2 the Rp of those wimpy 300Bs, so no need to use such high voltage anyway. 250V to 275V for B+ in triode mode will probably work fine. (+50V to +500V peaks, a 2X safety factor versus 1000V) An Edcor CXSE25-8-2.5K SE OT ($88) ought to work for SE. Or GXSE15-8-2.5K. ($38)
I just tried a 6HJ5 on the curve tracer here in triode mode with HV on the "plate+g2". I can get up to 1000V without any flashovers. I don't think I would want to rely on that for extended operation though. The 6HJ5 has got 2.8x the current capability, 2x the gm, and 1/2 the Rp of those wimpy 300Bs, so no need to use such high voltage anyway. 250V to 275V for B+ in triode mode will probably work fine. (+50V to +500V peaks, a 2X safety factor versus 1000V) An Edcor CXSE25-8-2.5K SE OT ($88) ought to work for SE. Or GXSE15-8-2.5K. ($38)
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I have never built a SE triode amp. Should I bother with global feedback? I need lots of gain especially if I want to use a little feedback, say 3db. I would like to use the tubes I have on hand which are tons of 12AX7's and 6SN7's.
This is something I just came up with. Output iron is Hammond 1627SE although I will probably go with Edcor. R8 is a 100k trimpot to adjust bias. Simulation shows just about 10 watts out @ 5% THD. The 6HJ5 is running @ 85mA. Total gain of amp is 18db.
This is something I just came up with. Output iron is Hammond 1627SE although I will probably go with Edcor. R8 is a 100k trimpot to adjust bias. Simulation shows just about 10 watts out @ 5% THD. The 6HJ5 is running @ 85mA. Total gain of amp is 18db.
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"how does the 6GE5 compare to the 6HB5?"
The 6HB5/21HB5 has a 34 mm long plate (same as 6HJ5) and the 6GE5 has a 28.5 mm long plate.
The 6HB5 cathode is 5 mm wide by 29 mm long, and the 6GE5 is 4.37 mm wide by 25 mm long. (6HJ5 is 6.67 mm wide by 32 mm long). So the relative cathode areas are (followed by plate length, DC mA rating and Watts diss.):
6GE5 109 28.5mm 175mA 17.5W
6HB5 145 34mm 230 mA 18W
6HJ5 213 34mm 280 mA 24W
The 6HB5 has 9 grid wires per 8 grid wires of the 6GE5 or 6HJ5
and finally, computing gm (@ max DC/4) per cathode area (followed by gm (@ maxDC/4) /maxDC):
6GE5 52.8 33
6HB5 70.9 (x8/9 = 63) 39
6HJ5 43.3 33
300B --- 33.65
2A3 --- 31 (based on 100 mA max DC, not specified in data)
These are giving a measure of gm per unit area at the same current density.
Lower #s should be more linear (for the same grid wire spacing). So theoretically the 6HB5 would be less linear. However, check the traces below, a bit hard to confirm. A little feedback, and they will all be the same, with the 6HB5's 18% extra gm per area to fix it.
Some pics of plates, then cathodes. (bottom to top: 12GE5, 21HB5/21JV6, 6HJ5, 35LR6, 36MC6)
And, finally some curve traces to try and decide: 12GE5 pentode and triode, then 21HB5 pentode and triode, and 6HJ5 pentode and triode. Probably need an FFT analysis to decide linearity between them.
The 6HB5/21HB5 has a 34 mm long plate (same as 6HJ5) and the 6GE5 has a 28.5 mm long plate.
The 6HB5 cathode is 5 mm wide by 29 mm long, and the 6GE5 is 4.37 mm wide by 25 mm long. (6HJ5 is 6.67 mm wide by 32 mm long). So the relative cathode areas are (followed by plate length, DC mA rating and Watts diss.):
6GE5 109 28.5mm 175mA 17.5W
6HB5 145 34mm 230 mA 18W
6HJ5 213 34mm 280 mA 24W
The 6HB5 has 9 grid wires per 8 grid wires of the 6GE5 or 6HJ5
and finally, computing gm (@ max DC/4) per cathode area (followed by gm (@ maxDC/4) /maxDC):
6GE5 52.8 33
6HB5 70.9 (x8/9 = 63) 39
6HJ5 43.3 33
300B --- 33.65
2A3 --- 31 (based on 100 mA max DC, not specified in data)
These are giving a measure of gm per unit area at the same current density.
Lower #s should be more linear (for the same grid wire spacing). So theoretically the 6HB5 would be less linear. However, check the traces below, a bit hard to confirm. A little feedback, and they will all be the same, with the 6HB5's 18% extra gm per area to fix it.
Some pics of plates, then cathodes. (bottom to top: 12GE5, 21HB5/21JV6, 6HJ5, 35LR6, 36MC6)
And, finally some curve traces to try and decide: 12GE5 pentode and triode, then 21HB5 pentode and triode, and 6HJ5 pentode and triode. Probably need an FFT analysis to decide linearity between them.
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I saw 150 watts continuous sine wave power for several minutes from a pair of 6HJ5's in Pete Millett's big red board amp running 650 volts into the big 3300 ohm Edcor. A pale red glow could be seen in a dark room at this level.
I published a design for this amp at the 125 WPC level in that thread (B+ reduced to 600V). I built 3 of them, and at least 10 others were built. My ex boss still has one of them hooked up to his Magnepans. I saw him today in my visit to the Motorola plant. It is operating fine and still has the original tube set in it.
Mine saw about a year of daily use with several multi sessions at the edge of clipping with LOUD bass heavy 70's rock and prog music. It's in a box somewhere, but it still has the original tube set.
ALL of the 6HJ5's that I have seen are just like yours. They all seem to be Raytheon's regardless of brand. The 6HD5's are also all Raytheon's even though they are all Motorola branded. Same tube, minor pinout difference, hard to find, but sometimes cheap.
Never tried either in triode, or SE.
Most "tube friendly" speakers don't need GNFB when driven with a triode SE.
The schematic you show is similar to some amps I have built including the TSE, but I tend to use a mosfet where you have the 6SN7. Sweep tubes generally don't need much positive G1 drive so the 6SN7 will probably do OK.
Funny you should say that.....
Ive been sorta getting into Triodes (or triode-mode) lately too....
(Maybe Ive always been--The old OTL's Ive done were all Triodes/Triode strapped pentodes)
That Yaqin EL84 pp --never sounded quite right--No matter what I did. It was pretty crap from new, so it got modded, and modded some more--To the point it sounded quite nice--It has very little resemblance to the original scheme.
Just turned it Triode-Mode yesterday, and reduced the FB to merely a 1-2dB and although power has dropped a bit--Its just SO much sweeter, lost that coarseness it had--Its still cathode-bias via CCS, some more messing called for, see if I can somehow do fixed-bias without mucking the appearance up too much, perhaps gain a watt or two (Very little room below-decks in this chassis....)
I think I'll try a PP Triode-Strapped 6HJ5 using George's scheme he developed with Chrish when the tubes turn up,-- OTL on hold.......
I dunno--SO many projects, and very little time....
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