For 6CW5/EL86, approx. 225 mA knee at 170 V g2 on the datasheet. (It's hard to set a value with pentodes due to the largely rounded knee. I try to take the 45 degree point on the curve, but that actually depends on the V and I scaling on the graph too.)
For the 150 V g2 knee, that would be around 225 x (150/170)^1.5 = 186 mA (216 mA for 1960 and later tubes, see below)
Has a 14 Watt rating for audio, 12 Watt rating for horiz. deflection.
Tube was registered in the US by Rogers Radio (Canada) and Philips in 1956.
By the way, there is an inconsistency on this Philips datasheet on pages 12 and 13, both show 170 V on g2, but have differenent dates, 1955 and 1960. So either there is a typo on page 13 and it should be more like 180 V on g2, or the tube was changed in 1960. Using the page 13 data as given, would lead to a 150 V g2 knee of 260 mA x (150/170)^1.5 = 216 mA
That appears to be consistant with page 15 for 200 V g2, so they must have changed the tube.
http://frank.pocnet.net/sheets/030/e/EL86.pdf
later datasheet, agrees with higher values:
http://frank.pocnet.net/sheets/010/e/EL86.pdf
For the 150 V g2 knee, that would be around 225 x (150/170)^1.5 = 186 mA (216 mA for 1960 and later tubes, see below)
Has a 14 Watt rating for audio, 12 Watt rating for horiz. deflection.
Tube was registered in the US by Rogers Radio (Canada) and Philips in 1956.
By the way, there is an inconsistency on this Philips datasheet on pages 12 and 13, both show 170 V on g2, but have differenent dates, 1955 and 1960. So either there is a typo on page 13 and it should be more like 180 V on g2, or the tube was changed in 1960. Using the page 13 data as given, would lead to a 150 V g2 knee of 260 mA x (150/170)^1.5 = 216 mA
That appears to be consistant with page 15 for 200 V g2, so they must have changed the tube.
http://frank.pocnet.net/sheets/030/e/EL86.pdf
later datasheet, agrees with higher values:
http://frank.pocnet.net/sheets/010/e/EL86.pdf
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http://frank.pocnet.net/sheets/137/6/6DN6.pdf (page 4)
Looks like around 381 mA knee for g2 = 150 V, g1 = 0
Sylvania, 1955, 15 Watt
Later tubes (1964?) may be rated 20 Watt (someone said this, I don't see it on any datasheet)
The 6DN6 .... are a bit high on filament current.
Looks like around 381 mA knee for g2 = 150 V, g1 = 0
Sylvania, 1955, 15 Watt
Later tubes (1964?) may be rated 20 Watt (someone said this, I don't see it on any datasheet)
The 6DN6 .... are a bit high on filament current.
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The original discussion regarding the high filament power consumption of the 25dn6 can be found on page 14 of this thread, where it was also found to have significantly higher grid current draw than most other sweep tubes. The 25dn6 is one of the older sweep tube designs out there and was probably made with a less efficient cathode coating and less-ideal grid construction compared to later sweep tube designs. That being said, it can certainly eat more than 15 watts- I believe TubeLab quoted getting 100 watts of a pair, but probably under conditions which would normally be considered "pure, unadulterated torture". I doubt they'd last very long under those conditions, but if you can get them for cheap, who cares if you end up sacrificing a few to the fire gods? 
I plead guilty on all counts!!!!
OK, I had some 25DN6's in my stash. They had been there for several years and never attracted my attention for the reasons mentioned, high heater power for a lowish plate rating. Then vacuumtubes.net ran this sale where the tubes got cheaper as the quantity went up for any tubes on their list.
Quantity Specials
So 100 tubes would cost $50 and 500 tubes cost $175. I bought 1000 tubes that day. The 25DN6 was on the list, so I dug out the ones I had for years and lit em up. I can say that the plate rating is conservative, and a pair will crank out 100 watts for hours without any glow of death. All sweep tubes were tested in Pete Millett's Engineers amp with socket adapters and a variable power supply. I bought 100 25DN6's for $50 (they have since been removed from the list). There are at least 3 different versions and the old ones have smaller plates and might not stand up to that type of abuse, but most were of the large plate variety.
The 13GB5 was on that list and I got some of those too. They seem even a bit higher powered with clipping occurring at 140 watts, and 90 watts is easy to get forever. I designed a new amp that has multiple feedback loops and both G1 and G2 are driven on the 13GB5's. This one makes 100 W at 1.5% distortion and 150 W at 5%. There is a slight glow at 150 watts, but everything is cool except the load resistor at 100 Watts.
Note, ESRC still has the 13GB5 for $1.
The 13GB5's were tested in a unique circuit that drives both the control grid and the screen grid. This allows screen drive type linearity at low idle currents without crossover distortion, while avoiding the problem of melting the screen grid with long term continuous full power operation with pure screen drive.
The operating point was 10 mA idle per tube, 550 to 650 volts on the plates and a 3300 ohm OPT.
I saw similar power outputs and distortion profiles in pure screen drive, but there was some grid glow when operated at full power with a sine wave just into clipping. A glowing screen grid can emit electrons that are attracted to the hugely positive plate leading to a runaway tube, followed by an arc and scattered mosfets and other dead parts.
There is no issue with playing music into a dummy load at full power since the excursions to the limit are few and far between.
The operating point was 10 mA idle per tube, 550 to 650 volts on the plates and a 3300 ohm OPT.
I saw similar power outputs and distortion profiles in pure screen drive, but there was some grid glow when operated at full power with a sine wave just into clipping. A glowing screen grid can emit electrons that are attracted to the hugely positive plate leading to a runaway tube, followed by an arc and scattered mosfets and other dead parts.
There is no issue with playing music into a dummy load at full power since the excursions to the limit are few and far between.
thanks tubelab.....do you have a link of the schematic posted somewhere?
my 12EN6 pp amp with a 5k a-a load and about 300 volts plate in a conventional pentode, with G2 regulated sounded so sweet to my ears....
I have just torn down my lab, packed it all up and started moving it and all my other belongings about 1200 miles. It will be over a year before my new house is built and everything is back to normal, although I will set something up in my temporary living space.
I can't post any of my recent discoveries since there are people who will copy my work and sell PC boards based on my designs. This has already happened, so I must keep this one secret until I have boards ready.
I designed the whole thing in LT spice using the 6GB5 and 6EJ7 models I found on this forum. I had about 4 hours of time to play with the breadboarded circuit before throwing it all in a box. It works far better than I expected, and sounds good, but some more tinker time is needed before I could be confident in the design. I have 3 simulated designs, but only breadboarded the simplest one.
I have a 125 WPC pentode amp with regulated screens too. It's one of Pete Millett's engineers amps with a Tubelab tune up on it. It runs 6HJ5's on 600 volts with a 3300 ohm OPT, 150 volts on G2, conventional G1 drive. It sounds so good that I built 3, but my boss has one of them. The schematic in on Pete's web site. I have one board set up for some tube rolling. The board is designed for 12 pin compactrons, but it isn't too hard to wire in Octals, Magnovals, and others. No 4D32's yet!
Perhaps you can post the name of the perpetrator, to prevent the others from dealing with such scum...
I have heard rumors of an SSE board copy, possibly from China, but I have never seen one. It is allegedly red in color and "looks just like yours." This rumor came from a guy at the Dayton hamfest who said he saw a red one in Europe. He was holding one of my boards in his hand and commenting on the curved runners leading to the output tube heaters. He seemed convinced that he saw a direct copy. If anyone has seen one I would like to know about it.
Another member of this forum has laid out a PC board from the Spud SE design that I published about 5 years ago. Granted, I posted the design, said that I was going to offer boards. My mother in law got cancer so Sherri and I spent 4 years caring for her terminally ill mother, and I never followed through with the board, or much else during that time. This person copied the design, and stated that it was a copy. He is selling them from his web site.
I can't call the guy a "scum", just an opportunist. Either way, I have lost my job of 41 years, and in the process of moving into the house left us by my mother in law. We will have our retirement house built, then move again. It will be a year or more before we move into it, then a while before my lab gets rebuilt.
The new house will have a much bigger lab space with all the features that this one didn't have, and about 6 years of "paper designs" will start to become reality. In the mean time, I am not going to give anyone a head start on some of the cool stuff that I have been working on.
Another member of this forum has laid out a PC board from the Spud SE design that I published about 5 years ago. Granted, I posted the design, said that I was going to offer boards. My mother in law got cancer so Sherri and I spent 4 years caring for her terminally ill mother, and I never followed through with the board, or much else during that time. This person copied the design, and stated that it was a copy. He is selling them from his web site.
I can't call the guy a "scum", just an opportunist. Either way, I have lost my job of 41 years, and in the process of moving into the house left us by my mother in law. We will have our retirement house built, then move again. It will be a year or more before we move into it, then a while before my lab gets rebuilt.
The new house will have a much bigger lab space with all the features that this one didn't have, and about 6 years of "paper designs" will start to become reality. In the mean time, I am not going to give anyone a head start on some of the cool stuff that I have been working on.
George, you have to give us an idea because the suspense is killing me already -- is it going to be very complex? High powered? A beginner level build? Inquiring minds want to know!
To make a direct copy of your work without your consent is not right, perhaps it's not "scummy", but it's not kosher either... Hope that you will settle into your retirement home and get back to making mad experiements soon!