I stopped in at Stan's shop in Florida last week in person to pick up my tubes, and talked with him for a couple hours. I know that he ships all over the world by the same method I use....USPS to the destination country, delivery by the postal service of the destination country.
The only two countries we have had delivery issues in are Italy and Russia. The stuff gets delivered to local customs agents, and disappears or an extraordinarily high "duty" is demanded for delivery. Neither of us has ever had a lost package to the UK.
The big triode in a 6JF7 is good for 2 to 3 watts in SE, maybe 15 in P-P class AB1. Not sure if they like AB2, or if it helps with that tube.
The 6JF6 is a typical 18 watt sweep tube, good for an easy 50 watts in P-P AB1 continuously, and could be squeezed to 100 watts in intermittent (normal HiFi listening with a 10+ db crest factor). 200 watts for a pair in class C RF would be possible if you don't keep the transmitter keyed a lot (say RTTY or PSK). 200 Watts in linear AB1 depends on your definition of the word "linear."
The cathodes on 6JF6 and 6KM6 are rated for a lot more current than the usual 17 watt sweep tubes. That was what piqued my curiosity about them.
I'm not sure where I came up with my 6JF6 stash; 6KM6 is a frequent $0.25- 0.50 tube at local hamfests - I don't think anything remaining in existence uses either type, and no need to fool with the oddball filament voltages.
Back on OT - I'm staring across the office at a couple of NOS 6GB5 sitting on a 51S-1 and waiting on a truip to the warehouse of junk. I paid $0.50 for the pair about a month ago.
Win W5JAG
I'm not sure where I came up with my 6JF6 stash; 6KM6 is a frequent $0.25- 0.50 tube at local hamfests - I don't think anything remaining in existence uses either type, and no need to fool with the oddball filament voltages.
Back on OT - I'm staring across the office at a couple of NOS 6GB5 sitting on a 51S-1 and waiting on a truip to the warehouse of junk. I paid $0.50 for the pair about a month ago.
Win W5JAG
It is nice to find 6.3V heater TV Sweeps for reasonable prices. The 21V - 22V heater types can still be run from a regulated 24V supply (a cheap Ebay switcher), with the Vout adjusted down a little. So I'm fine with those too, and no hum issue.
The 6/17/22KV6A is in the same class with the 6JF6, 6JG6, 6KM6, 6JR6, 6JU6 tubes with 275 mA max DC, 950 mA peak, cathode ratings.
Then there is 6HJ5 at 280 mA/1000 mA and 21LG6A at 315/1100 mA. All the same size plates and bottle. A lot of price variation for different heater V's of course. 6HJ5's already ran out of supply once, but there -might- be a 100 more now, maybe, maybe not. No idea about the other ones.
Then there are all the 30 Watt to 40 Watt Pdiss Sweeps, and high prices too. 6KG6A/EL509 will get you a 500mA/1400mA cathode for $50 and up.
Pics: LG HJ KM KV
The 6/17/22KV6A is in the same class with the 6JF6, 6JG6, 6KM6, 6JR6, 6JU6 tubes with 275 mA max DC, 950 mA peak, cathode ratings.
Then there is 6HJ5 at 280 mA/1000 mA and 21LG6A at 315/1100 mA. All the same size plates and bottle. A lot of price variation for different heater V's of course. 6HJ5's already ran out of supply once, but there -might- be a 100 more now, maybe, maybe not. No idea about the other ones.
Then there are all the 30 Watt to 40 Watt Pdiss Sweeps, and high prices too. 6KG6A/EL509 will get you a 500mA/1400mA cathode for $50 and up.
Pics: LG HJ KM KV
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Seeing as how this thread started out with Screen Drive, to get back more on topic, here is a list of TV Sweep tubes with knee currents at 150V on g2. Ordered by knee current. 6GB5 about half way down the list. The still available $1 12HE7/38HE7 oddball tube is just above it.
List of knee currents for g2 = 150 V, g1 = 0 V, Vp = 60 to 80 V
<tube> <Watts> <mA knee@150Vg2> <gm1> <Mu> <maxDCmA> <registered by> <date>
6LF6 40W 1144mA@150V 15K@125mA Mu3 500mADC Amperex 1968
6KG6/EL509 34W 1135mA@150V 13K@150mA Mu3.2 500mADC Amperex 1965
6MC6 33W 1130mA@150V 14K@125mA Mu4 400mADC RCA (6LX6 clone) 1972
13E1 90W(absmax) 1120mA@150V 35K@500mA Mu4.5 800mADC AEI 1961
6MH6 38.3W 1100mA@150V 14K@125mA Mu4 500mADC GE (up-rated 6LX6,6KD6,26HU5) 1972
6MB6 38W 1085mA@150V 14K@110mA Mu3.5 400mADC Sylvania 1971
6LR6 30W 1085mA@150V 16K@140mA Mu3.5 375mADC Sylvania 1968
6LX6/6KD6/26HU5 33W 1080mA@150V 14K@125mA Mu4 400mADC GE 1969/1965/1969
6LW6 40W 1050mA@150V 12K@125mA Mu3.7 400mADC GE 1971
6KN6 30W 1050mA@150V 16K@100mA Mu4.5 400mADC Sylvania 1965 (later versions are 6KD6)
6LZ6 30W 940mA@150V 11K@140mA Mu3 350mADC RCA 1971
6LB6/A 30W/35W 825mA@150V 13.4K@105mA Mu4 315mADC GE 1967
6JE6C/6JS6C 30W 789mA@150V 10.5K@130mA Mu3 350mADC Sylvania 68/69
6JE6 24W 762mA@150V 9.6K@115mA Mu3 315mADC RCA 1962
6JS6/6HF5 28W 749mA@150V 11.5K@130mA Mu3 315mADC GE 1964/1963
6MJ6 30W 740mA@150V 11K@100mA Mu3.6 350mADC RCA 1973
6LG6 28W 740mA@150V 11.5K@90mA Mu3.6 315mADC GE 1967
6LQ6 30W 715mA@150V 7.5K@95mA Mu3 350mADC RCA 1967
6ME6 30W 700mA@150V 9.6@130mA Mu3.5 350mADC RCA 1971
6DQ5 24W 690mA@150V 10.5K@110mA Mu3.3 315mADC RCA 1957
6JF6/6JG6 17W 660mA@150V 10K@80mA Mu4.1 275mADC RCA 1965/1964
6KM6 20W 630mA@150V 9.5K@80mA Mu4 275mADC RCA 1965
6HD5/6HJ5 24W 630mA@150V 10K@80mA Mu4.2 280mADC Raytheon 1962/1963
6JR6/6JU6 17W 600mA@150V 7K@45mA Mu4.7 275mADC RCA 1968/1966
6JZ6/21HB5A 18W 560mA@150V 9K@46mA Mu4.8 230mADC GE 1966/1964
12HE7 10-15W 540mA@150V 8.8K@60mA Mu4.2 200mADC GE (15W if damper disabled) 1964
6CL5 25W 514mA@150V 6.5K@90mA Mu3 240mADC Sylvania 1955
6GB5/29KQ6/EL500 17W 500mA@150V 13K@100mA Mu5.1 275mADC Amperex 1961/Matsushita 1959/Philips 1961?
6KV6/A 20-28W 488/610mA@150V 6K@40mA Mu4 275mADC RCA (re-rated 6KM6?) 1967/1969
6HB5/6GY5/21JV6/6KE6/16KA6 18W 475mA@150V 9.1K@50mA Mu4.7 230mADC GE/GE/GE/Ray/Tung 1962/1962/1965/1965/1964
6EX6 22W 460mA@150V 7.7K@67mA Mu4.2 220mADC Raytheon (up-rated 6CD6) 1959
6CB5/A 23W 440mA@150V 8.8K@90mA Mu3.8 240mADC RCA 1954/1956
6CD6/GA 15/20W 422mA@150V 7.7K@75mA Mu3.9 200mADC RCA/GE 1949/1954
6GT5/6GJ5/6JT6/6JB6/6GW6 17.5W 380mA@150V 7.1K@70mA Mu4.4 175mADC RCA 1961/1961/1964/1962/1961
6GE5 17.5W 350mA@150V 7.3K@65mA Mu4.4 175mADC GE 1961
6GF5 9W 345mA@150V 4.7K@34mA Mu4.2 160mADC GE 1961
6JM6/6JN6/6FW5/6GC6 17.5W 340mA@150V 7.3K@70mA Mu4.4 175mADC GE 1964/1964/1960/1960
6DQ6B/6GV5 17.5W/18W 330mA@150V 7.3K@65mA Mu4.4 175mADC GE 1959/1962
6DQ6/A 18W 280mA@150V 6.6K@55mA Mu4.1 120/155mADC CBS/RCA 1955/1956
6JA5/10JA5 19W 276mA@150V 10.3K@95mA Mu5.5 110mADC GE 1971
6LU8/6LR8//6MY8 14//16W 265mA@150V 9.3K@56mA Mu6.5 75mADC Sylvania 1964/1964//1970(Toshiba)
6AV5/GA///6BQ6/GA 11W 255ma@150V 5.9K@57mA Mu4.3 110mADC CBS/GE 1949/1955 /// CBS/Syl 1949/1953
KT120 60W 221ma@150V 190mADC
KT90 50W 220mA@150V
6Y6G/GT/GA 12.5W 200mA@150V Ray 1937/KenRad 1939/Syl 1954
6550A 35W/42W 190mA@150V 11K@140mA 190mADC
6W6GT 10W 185mA@150V 8K@46mA Mu6.2 65mADC CBS 1939
KT88 35W 170mA@150V 175mADC
6CA7/EL34 25W 107mA@150V 11K@100mA Mu10.5 150mADC Philips 1952
6JC5 19W 80mA@150V 4.1K@43mA Mu7 75mADC Sylvania 1971
6L6/G/GA/GB/GC 30W 77mA@150V 4.7K@40mA Mu8 110mADC RCA 1936/Ray 1936/Syl 1943/Syl 1954/GE 1958
6HB6 10W 70mA@150V 20K@40mA Mu33 60mADC Raytheon 1961
6GK6 13.2W 65mA@150V 11.3K@48mA Mu19 65mADC CBS 1959
6BQ5/EL84 12W 65mA@150V 11.3K@48mA Mu19.5 65mADC Rogers 1956
6V6G/GT 14W 45mA@150V 4.1K@45mA Mu9.8 40mADC KenRad 1936/CBS 1939
List of knee currents for g2 = 150 V, g1 = 0 V, Vp = 60 to 80 V
<tube> <Watts> <mA knee@150Vg2> <gm1> <Mu> <maxDCmA> <registered by> <date>
6LF6 40W 1144mA@150V 15K@125mA Mu3 500mADC Amperex 1968
6KG6/EL509 34W 1135mA@150V 13K@150mA Mu3.2 500mADC Amperex 1965
6MC6 33W 1130mA@150V 14K@125mA Mu4 400mADC RCA (6LX6 clone) 1972
13E1 90W(absmax) 1120mA@150V 35K@500mA Mu4.5 800mADC AEI 1961
6MH6 38.3W 1100mA@150V 14K@125mA Mu4 500mADC GE (up-rated 6LX6,6KD6,26HU5) 1972
6MB6 38W 1085mA@150V 14K@110mA Mu3.5 400mADC Sylvania 1971
6LR6 30W 1085mA@150V 16K@140mA Mu3.5 375mADC Sylvania 1968
6LX6/6KD6/26HU5 33W 1080mA@150V 14K@125mA Mu4 400mADC GE 1969/1965/1969
6LW6 40W 1050mA@150V 12K@125mA Mu3.7 400mADC GE 1971
6KN6 30W 1050mA@150V 16K@100mA Mu4.5 400mADC Sylvania 1965 (later versions are 6KD6)
6LZ6 30W 940mA@150V 11K@140mA Mu3 350mADC RCA 1971
6LB6/A 30W/35W 825mA@150V 13.4K@105mA Mu4 315mADC GE 1967
6JE6C/6JS6C 30W 789mA@150V 10.5K@130mA Mu3 350mADC Sylvania 68/69
6JE6 24W 762mA@150V 9.6K@115mA Mu3 315mADC RCA 1962
6JS6/6HF5 28W 749mA@150V 11.5K@130mA Mu3 315mADC GE 1964/1963
6MJ6 30W 740mA@150V 11K@100mA Mu3.6 350mADC RCA 1973
6LG6 28W 740mA@150V 11.5K@90mA Mu3.6 315mADC GE 1967
6LQ6 30W 715mA@150V 7.5K@95mA Mu3 350mADC RCA 1967
6ME6 30W 700mA@150V 9.6@130mA Mu3.5 350mADC RCA 1971
6DQ5 24W 690mA@150V 10.5K@110mA Mu3.3 315mADC RCA 1957
6JF6/6JG6 17W 660mA@150V 10K@80mA Mu4.1 275mADC RCA 1965/1964
6KM6 20W 630mA@150V 9.5K@80mA Mu4 275mADC RCA 1965
6HD5/6HJ5 24W 630mA@150V 10K@80mA Mu4.2 280mADC Raytheon 1962/1963
6JR6/6JU6 17W 600mA@150V 7K@45mA Mu4.7 275mADC RCA 1968/1966
6JZ6/21HB5A 18W 560mA@150V 9K@46mA Mu4.8 230mADC GE 1966/1964
12HE7 10-15W 540mA@150V 8.8K@60mA Mu4.2 200mADC GE (15W if damper disabled) 1964
6CL5 25W 514mA@150V 6.5K@90mA Mu3 240mADC Sylvania 1955
6GB5/29KQ6/EL500 17W 500mA@150V 13K@100mA Mu5.1 275mADC Amperex 1961/Matsushita 1959/Philips 1961?
6KV6/A 20-28W 488/610mA@150V 6K@40mA Mu4 275mADC RCA (re-rated 6KM6?) 1967/1969
6HB5/6GY5/21JV6/6KE6/16KA6 18W 475mA@150V 9.1K@50mA Mu4.7 230mADC GE/GE/GE/Ray/Tung 1962/1962/1965/1965/1964
6EX6 22W 460mA@150V 7.7K@67mA Mu4.2 220mADC Raytheon (up-rated 6CD6) 1959
6CB5/A 23W 440mA@150V 8.8K@90mA Mu3.8 240mADC RCA 1954/1956
6CD6/GA 15/20W 422mA@150V 7.7K@75mA Mu3.9 200mADC RCA/GE 1949/1954
6GT5/6GJ5/6JT6/6JB6/6GW6 17.5W 380mA@150V 7.1K@70mA Mu4.4 175mADC RCA 1961/1961/1964/1962/1961
6GE5 17.5W 350mA@150V 7.3K@65mA Mu4.4 175mADC GE 1961
6GF5 9W 345mA@150V 4.7K@34mA Mu4.2 160mADC GE 1961
6JM6/6JN6/6FW5/6GC6 17.5W 340mA@150V 7.3K@70mA Mu4.4 175mADC GE 1964/1964/1960/1960
6DQ6B/6GV5 17.5W/18W 330mA@150V 7.3K@65mA Mu4.4 175mADC GE 1959/1962
6DQ6/A 18W 280mA@150V 6.6K@55mA Mu4.1 120/155mADC CBS/RCA 1955/1956
6JA5/10JA5 19W 276mA@150V 10.3K@95mA Mu5.5 110mADC GE 1971
6LU8/6LR8//6MY8 14//16W 265mA@150V 9.3K@56mA Mu6.5 75mADC Sylvania 1964/1964//1970(Toshiba)
6AV5/GA///6BQ6/GA 11W 255ma@150V 5.9K@57mA Mu4.3 110mADC CBS/GE 1949/1955 /// CBS/Syl 1949/1953
KT120 60W 221ma@150V 190mADC
KT90 50W 220mA@150V
6Y6G/GT/GA 12.5W 200mA@150V Ray 1937/KenRad 1939/Syl 1954
6550A 35W/42W 190mA@150V 11K@140mA 190mADC
6W6GT 10W 185mA@150V 8K@46mA Mu6.2 65mADC CBS 1939
KT88 35W 170mA@150V 175mADC
6CA7/EL34 25W 107mA@150V 11K@100mA Mu10.5 150mADC Philips 1952
6JC5 19W 80mA@150V 4.1K@43mA Mu7 75mADC Sylvania 1971
6L6/G/GA/GB/GC 30W 77mA@150V 4.7K@40mA Mu8 110mADC RCA 1936/Ray 1936/Syl 1943/Syl 1954/GE 1958
6HB6 10W 70mA@150V 20K@40mA Mu33 60mADC Raytheon 1961
6GK6 13.2W 65mA@150V 11.3K@48mA Mu19 65mADC CBS 1959
6BQ5/EL84 12W 65mA@150V 11.3K@48mA Mu19.5 65mADC Rogers 1956
6V6G/GT 14W 45mA@150V 4.1K@45mA Mu9.8 40mADC KenRad 1936/CBS 1939
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From the datasheet of 21EX6 vs 26DQ5
Maximum Plate Dissipation: 22W vs 24W.. okay
Maximum Peak Cathode Current: 770mA vs 1,100mA.. not okay. Are these tested numbers or the 21EX6 can actually reach the same 1,100mA? I need only around 900mA as that's what the Class B loadline for 2K4 OPT at 600V that i drew called for.
I could just settle for 150WPC using Vak=500V.. that's plenty enough for me.
Maximum Plate Dissipation: 22W vs 24W.. okay
Maximum Peak Cathode Current: 770mA vs 1,100mA.. not okay. Are these tested numbers or the 21EX6 can actually reach the same 1,100mA? I need only around 900mA as that's what the Class B loadline for 2K4 OPT at 600V that i drew called for.
I could just settle for 150WPC using Vak=500V.. that's plenty enough for me.
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I would have to go by the datasheet numbers on that.
For 900 mA, looks like 6HJ5 (1000 mA) or 21LG6 (1100 mA) or 35LR6 (1300 mA) would be your tube. (or 26DQ5 1000 mA) The 1st two are inexpensive, but of unknown availability. (try Vacuumtubes.net for 6HJ5, last I heard)
6/17/22KV6 and 6KM6 are another possibility, @ 950 mA and 20 Watts
(along with 6JF6, 6JG6, 6JR6, 6JU6 at 950 mA but only 17 Watts.)
another one, 6KN6 42KN6 1500 mA 30 Watt moderate price
For 900 mA, looks like 6HJ5 (1000 mA) or 21LG6 (1100 mA) or 35LR6 (1300 mA) would be your tube. (or 26DQ5 1000 mA) The 1st two are inexpensive, but of unknown availability. (try Vacuumtubes.net for 6HJ5, last I heard)
6/17/22KV6 and 6KM6 are another possibility, @ 950 mA and 20 Watts
(along with 6JF6, 6JG6, 6JR6, 6JU6 at 950 mA but only 17 Watts.)
another one, 6KN6 42KN6 1500 mA 30 Watt moderate price
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Did Jazbo8 kill the thread with that question?
Being interested in hearing about screen-drive amps could we revive this thread?
It was dead 8 months before Jazbo's post. I assume he was seeking input just as you are doing.
He tried to change his nickname, may be succeeded?
Edit: I sent him e-mail. If does not answer, I will call him tomorrow.
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Probably 38/12HE7, were on the famous $1 list.
Have seen them in quantity for $0.35
The 38HE7 often can run just the pentode with 21V Htr across pins 10 and 12. Pentode can then be uprated to 15 Watt without the Damper diode running. (has a large plate)
6P41S (Russian) is another cheap one. 14 Watt nominal.
21HB5A used to be on the $1 list, $6 now. 18 Watt nominal, but has a plate size equal to many 24 to 28 Watt tubes.
26DQ5 were $3 when ESRC had them, $5 now. 24 Watt
6HJ5 24 Watt used to be $3, But you can't hardly find them anymore, $12 now. Essentially a 6DQ5 without a plate cap.
33/21JV6 $3 18 Watts (same tube as 21HB5)
6EX6/6CD6A 22 Watt $6
21EX6 22 Watt $3
25/6DN6 15-20 Watt $3 (sometimes $0.50 in quantity)
6197 7.5 Watt (sometimes $0.33 to $0.50 in quantity, parallel them up, 5 or 6 to equal a TV Sweep with very high gm)
6DQ5 24 Watt $10
21LG6A 28 Watt, $4 An up-rated 6DQ5.
6CB5A 26 Watt, $5
21/6GY5 18 Watt, $3
17/6GV5, 17JN6, 17GE5 17.5 Watt, $3
22KV6 28 Watt, $6
plenty more I'm sure, and likely some Russian tubes also
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6197 looks like a very interesting little tube, low g1 drive requirements, maybe 10 watts or more a pair output in push pull conventional drive. Maybe a good low complexity, moderate power output amp candidate. Could probably drive the dickens out if them with a single 6CG7 as a voltage amp and concertina splitter per channel.
Hmmmm.
Hmmmm.
6197 video tube curves. Pics 1 and 2: g1 drive pentode, and triode curves. Who needs g2 drive when you have g1 curves like this.
Will certainly give (in parallel) a unique linear power tube with outrageous gm. ( 11000 gm per tube ) Good triode curves too.
One could go even further with paralleled 12HL7 video tubes for higher gm. Were on the $1 list briefly, now $3. Frame grid 1, 21000 gm per tube.
(will need some g1-k diode protection to avoid grid current into frame grid 1) Pentode curves are maybe not quite as nice as the 6197, but curve tracer selected 12HL7s can give remarkably linear triode curves. (3rd and 4th pics)
Will certainly give (in parallel) a unique linear power tube with outrageous gm. ( 11000 gm per tube ) Good triode curves too.
One could go even further with paralleled 12HL7 video tubes for higher gm. Were on the $1 list briefly, now $3. Frame grid 1, 21000 gm per tube.
(will need some g1-k diode protection to avoid grid current into frame grid 1) Pentode curves are maybe not quite as nice as the 6197, but curve tracer selected 12HL7s can give remarkably linear triode curves. (3rd and 4th pics)
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