It might. Vertical section was CW, not pulse like horizontal.
Also, it was 59.94Hz fields for colour. 29.97Hz frames (I went to school for television production when t hings were still analog). And what a cool kludge that was from 30Hz/60Hz from B&W days!
Sure you needed a Color killer - Wikipedia but cool none the less.
Also, it was 59.94Hz fields for colour. 29.97Hz frames (I went to school for television production when t hings were still analog). And what a cool kludge that was from 30Hz/60Hz from B&W days!
Sure you needed a Color killer - Wikipedia but cool none the less.
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So did I, but it was in 1967 - 1970. Some things get lost in 68 year old brain cells.
The color killer is basically a squelch circuit for the color signal since colored "snow" is not natural looking and thus far more objectional to human brains. Similar circuits exist to kill the stereo demodulator on weak FM signals to eliminate stereo noise, or kill the audio completely on very weak or no signal. Fancy tuners weaken the stereo image on the high audio frequencies on weak signals, but preserve the stereo image in the mid range.
The original TV sweep tube was the 6BG6G which is a 6L6G with a different pinout and a top cap. As the sweep tube progressed the grid pitch and spacing got closer, making the screen grid much more sensitive. At the same time the cathode got bigger to put far more electrons into the space charge cloud to improve efficiency. The original 6L6 based design went away quickly.
Early TV vertical sweep circuits used the 6SN7. As TV's got bigger, the 6SN7 became a 6BL7 or a 6BX7. Some sets even used a triode wired 6V6 or 6CK4. My 1957 vintage 21 inch round CRT color TV used a 6BL7. As TV's got rectangular a bit more power was needed and that brought pentodes like the 6W6. The vertical sweep tube never evolved much beyond the 6W6 based design of the 50's because it didn't need to.
Linearity is important to keep round things on the screen round, and only a few watts of power are needed, and you are not running the flyback from the vertical sweep tube, only a pair of coils. My early DIY guitar amps were just the vertical sweep section from a TV including the OPT with a 12AX7 in front on some of them.
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6W6, 6LU8 and 10JA5 (Vertical Sweeps) all use the lower grid 2 voltage range like Horiz. Sweeps do.
I tested a 10JA5 against a 12GE5 in triode mode and the 12GE5 had better triode curves. I count on the "roll-over" test to determine if the gm has been pushed by putting grid 1 closer to the cathode. So I would take a GE5/JN6 over the Vertical tubes for linearity. Maybe the vertical circuitry in a TV had some special compensation to get linear scanning?
Then there is rounded screen versus flat screen CRTs. The rounded one would want linear angle deflection, the flat screen would want the scan to slow a little toward the edges.
I tested a 10JA5 against a 12GE5 in triode mode and the 12GE5 had better triode curves. I count on the "roll-over" test to determine if the gm has been pushed by putting grid 1 closer to the cathode. So I would take a GE5/JN6 over the Vertical tubes for linearity. Maybe the vertical circuitry in a TV had some special compensation to get linear scanning?
Then there is rounded screen versus flat screen CRTs. The rounded one would want linear angle deflection, the flat screen would want the scan to slow a little toward the edges.
I'm comparing the data sheets for 6JC5 (vertical deflection, Pdiss 19W) and 6GE5 (horiz deflection, Pdiss 17.5W)
6JC5 has max Vg2 = 300V
6GE5 has max Vg2 = 220V
I heard a rumor that 6JC5 is very similar to 6V6 but with higher dissipation ratings for plate and Vg2. That's supposed to make a good triode and should be good as a triode with plate voltage =/> 300V.
How about 6GE5? If it's more linear as a triode than 6JC5, can it be used with Vplate = 300V? Or would that wear it out too quickly? Is the plate voltage not that important compared to plate power dissipation? (In other words, keep the plate+screen dissipation <18W and it should be good as a triode with Vplate = 300V?)
6JC5 has max Vg2 = 300V
6GE5 has max Vg2 = 220V
I heard a rumor that 6JC5 is very similar to 6V6 but with higher dissipation ratings for plate and Vg2. That's supposed to make a good triode and should be good as a triode with plate voltage =/> 300V.
How about 6GE5? If it's more linear as a triode than 6JC5, can it be used with Vplate = 300V? Or would that wear it out too quickly? Is the plate voltage not that important compared to plate power dissipation? (In other words, keep the plate+screen dissipation <18W and it should be good as a triode with Vplate = 300V?)
Thomas Meyer wrote a blog and built a triode strapped SE amplifier with the 6GE5.
This is the link VinylSavor: 6GE5
It is a summary of his 5 posts on the tube if you scroll down you will find his schematic, build and tube of the month review.
He used a 5k ohm OT with approximately 300 volts from plate to cathode.
Steve
This is the link VinylSavor: 6GE5
It is a summary of his 5 posts on the tube if you scroll down you will find his schematic, build and tube of the month review.
He used a 5k ohm OT with approximately 300 volts from plate to cathode.
Steve
Whoa! Really? 30 watts? Is that in class AB2?
I only need 10W, honestly, but I try to get as good damping and low THD as I can get without NFB. Perhaps running a PP pair of *GE5 into a 5k plate-plate OPT could give me 10W or more in class A or AB1? That would be amazing from a pair of triodes with only a 320V B+.
Is that really achievable?
I was digging through a box of used hamfest tubes looking for some "test specimens" and I found one of those "winglet" Sylvania 6DQ5's mentioned by smoking-amp in post #1570 and other places.
It is shown here next to a Sylvania 26LW6. The plate structure looks identical except for the taller plate in the 26LW6.
The 6DQ5 has a 1.5 inch tall plate. The 26LW6 is RATED for 40 watts, and most will eat 50 if they were built right. It has a 2 inch tall plate. Simple dumm blonde 'rithmetic tells me that this 6DQ5 should eat 30 watts or more. We will see.....if it's good.
It is shown here next to a Sylvania 26LW6. The plate structure looks identical except for the taller plate in the 26LW6.
The 6DQ5 has a 1.5 inch tall plate. The 26LW6 is RATED for 40 watts, and most will eat 50 if they were built right. It has a 2 inch tall plate. Simple dumm blonde 'rithmetic tells me that this 6DQ5 should eat 30 watts or more. We will see.....if it's good.
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You ever torture test any of the Russian 6P45C? Always wondered how they held up.
I don't have any to "test." Russian tubes were simply not available in my formative tube years, so I never really knew about them.
When I restarted my vacuum tube journey in the mid 90's Stan (ESRC) and his father Irving (founder of ESRC) were regular fixtures on the South Florida hamfest circuit. Their warehouse and business was about a mile from where I worked, so I visited often, sometimes just to look at stuff and remember things.
Any tubes that I had to pay for came from Stan, and he never had any Russian stuff, so I just never had them to play with.
A couple of possibly dumb questions related to sweep pentodes...
1) Which of the many big pentodes have no plate cap but pentode rp down around 5k ohms? I'm intrigued by the idea of running a PP pentode amp that has pretty good damping factor right from the git-go, before NFB, and...
2) Seeing that most (if not all) of the big, low rp sweep pentodes require a plate cap, what wire and plate caps do you guys recommend I buy, since I have none?
The idea of >500V and >75ma exposed on the top of the chassis makes me want to avoid stuff with cheap insulators that crack and break, or other possible pitfalls.
Thanks.
1) Which of the many big pentodes have no plate cap but pentode rp down around 5k ohms? I'm intrigued by the idea of running a PP pentode amp that has pretty good damping factor right from the git-go, before NFB, and...
2) Seeing that most (if not all) of the big, low rp sweep pentodes require a plate cap, what wire and plate caps do you guys recommend I buy, since I have none?
The idea of >500V and >75ma exposed on the top of the chassis makes me want to avoid stuff with cheap insulators that crack and break, or other possible pitfalls.
Thanks.
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...Yeah, the curves are way too “flat” on all the capless sweeps I know of. You could use two in parallel to get Rp down, if you can stand the extra heater power. I end up using ceramic caps and wire that was scrounged out of an old scrapped HVAC system with top-cap tubes. Rated 600 volts and 105C. Still possible to get a finger or pointed instrument under the cap, if you try hard enough. Maybe not the best thing if you’ve got cats that like to snuggle up against running tubes.
6HJ5, 6HD5 24 Watt cap-less Sweep tube, 5000 Ohm Rp, 10,000 gm at 80 mA very similar to 6DQ5 and 21LG6A, were very popular and cheap, $3 to $5, until the supply ran out, can still find a few for $12 or $15.
17/22KV6A cap-less 22 Watt (in sweep tube mode, 28 Watt in regulator mode), same specs as 6HJ5 above, but Novar socket. (very hard to find real Novar sockets now, but some of the 9 pin Compactron / Magnoval sockets can be modified with a small screw driver.) These were like $2 or $3 back in the sale days. $15 or so now.
Both tubes have the same size plate as a KT88.
Oh yeah. 10JA5 and 6JC5 19 Watt cap-less Vertical Sweeps. Higher Rp though.
Another cap-less tube type are the big triode regulator tubes, 6528, 6336, 6080, 7241, .... really low Rp.
200 Ohm per plate for 6336, 67 Ohm for 7241.
17/22KV6A cap-less 22 Watt (in sweep tube mode, 28 Watt in regulator mode), same specs as 6HJ5 above, but Novar socket. (very hard to find real Novar sockets now, but some of the 9 pin Compactron / Magnoval sockets can be modified with a small screw driver.) These were like $2 or $3 back in the sale days. $15 or so now.
Both tubes have the same size plate as a KT88.
Oh yeah. 10JA5 and 6JC5 19 Watt cap-less Vertical Sweeps. Higher Rp though.
Another cap-less tube type are the big triode regulator tubes, 6528, 6336, 6080, 7241, .... really low Rp.
200 Ohm per plate for 6336, 67 Ohm for 7241.
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Some "Dark Horse" candidates for cap-less Sweep tubes:
These are only rated 17 to 18 Watt Pdiss, but they have the same big 35mm long plate size as KT88, 17KV6A, 6HJ5, 6DQ5, 6JE6, 6LQ6 ...
22JG6 data says 12,000 Ohm Rp, but the datasheet CURVES look more like 6000 Ohm. Novar socket.
21HB5A 9900 Ohm Rp
21JV6 11000 Ohm Rp
22JR6 18000 Ohm Rp, Novar socket
Some of the tubes occasionally have a grid 1 cooler fin up top. Making them look identical to a 17KV6A.
I'm not aware of Tubelab (George) having done any audio "ratings..." for these tubes, but they are clearly able to do more than the TV Sweep ratings in audio use.
These are only rated 17 to 18 Watt Pdiss, but they have the same big 35mm long plate size as KT88, 17KV6A, 6HJ5, 6DQ5, 6JE6, 6LQ6 ...
22JG6 data says 12,000 Ohm Rp, but the datasheet CURVES look more like 6000 Ohm. Novar socket.
21HB5A 9900 Ohm Rp
21JV6 11000 Ohm Rp
22JR6 18000 Ohm Rp, Novar socket
Some of the tubes occasionally have a grid 1 cooler fin up top. Making them look identical to a 17KV6A.
I'm not aware of Tubelab (George) having done any audio "ratings..." for these tubes, but they are clearly able to do more than the TV Sweep ratings in audio use.
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