Surprised no one commented on this article showing the lineage of sweep tubes starting with the 807.
MJ^9203_(05)horiz-output-tube_Morikawa-Miyazaki.pdf - Google Drive
MJ^9203_(05)horiz-output-tube_Morikawa-Miyazaki.pdf - Google Drive
I never saw it until this post. I have personally "tested" every US sweep tube that's on that tree, and dozens more. My favorite is the 6LW6.
A pair can be seen cranking out 250 watts watts in post#55 and 56 of this thread:
UNSET is coming?
A pair can be seen cranking out 250 watts watts in post#55 and 56 of this thread:
UNSET is coming?
Possibly it is explained in the text (...) but I'm wondering why the EL500/6GB5 is on the right (US?) side of the tree. Magnoval types were common in Europe, not to common in the US.
I have some types on this tree, but also several which are not. Just check the extensive list in the big TV tubes thread. Who volunteers to add them to the tree 😀
One of these days I was thinking about differences/evolutions in construction like cavitrap anodes vs simple boxes, rectangular vs rounded boxes, cooling fins on g1, on g1 and g2 or not at all...
I have some types on this tree, but also several which are not. Just check the extensive list in the big TV tubes thread. Who volunteers to add them to the tree 😀
One of these days I was thinking about differences/evolutions in construction like cavitrap anodes vs simple boxes, rectangular vs rounded boxes, cooling fins on g1, on g1 and g2 or not at all...
A misunderstanding 807 never was intended as television sweep tube it was
created as a shortwave transmitter tube . The fact that some early tv receivers used 807 was more of a lack of dedicated such tubes.
807 (vacuum tube - Wikipedia)
Seem to be some pretty odd associations on that tree. 6GB7 related to 6DQ5?
I've got some of each and I don't see anything similar between them.
I could see 6GB7 related to 6DQ6, 6GE5/6JN6.
6BQ6 and 6AV5.
6KN6 started out as a dual paralleled pentode, then changed to a 6KD6 later.
6HJ5 and 6LG6 are directly descended from 6DQ5. 6MJ6 similar to 6LG6.
6LQ6 and 6JE6 and 6ME6 closely related, 6JS6 similar.
6MC6 nearly same as 6LX6, 6KD6, 6MH6, and 26HU5.
6EX6 is upgraded 6CD6.
25HX5, E235L, 7751 appear to be upgraded EL36, 6CM5, 50JY6.
6HE7 appears to be half of the old 42KN6 and similar to 6HB5.
Lots more associations likely.
Need to have a list of JEDEC release dates to determine what came 1st etc.
I've got some of each and I don't see anything similar between them.
I could see 6GB7 related to 6DQ6, 6GE5/6JN6.
6BQ6 and 6AV5.
6KN6 started out as a dual paralleled pentode, then changed to a 6KD6 later.
6HJ5 and 6LG6 are directly descended from 6DQ5. 6MJ6 similar to 6LG6.
6LQ6 and 6JE6 and 6ME6 closely related, 6JS6 similar.
6MC6 nearly same as 6LX6, 6KD6, 6MH6, and 26HU5.
6EX6 is upgraded 6CD6.
25HX5, E235L, 7751 appear to be upgraded EL36, 6CM5, 50JY6.
6HE7 appears to be half of the old 42KN6 and similar to 6HB5.
Lots more associations likely.
Need to have a list of JEDEC release dates to determine what came 1st etc.
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The 807 was in excess supply right after WWII. New ones could be bought for under $1, often 50 cents or a quarter at the local Army-Navy surplus store as late as the early 60's. The price was determined by how many they had.
The metal 6L6G and the metal 6L6 came first. The 6L6GA brought a smaller glass envelope.
The 6L6GB, 807, 1625, 6BG6G, 6BD5GT, and 807 all had the same core guts with modifications made for each chosen application.
As stated the 807, 1625, and a couple others I can't remember were 6L6GB's with shielding added to the area below the bottom mica, and a different base. The 1625 is an 807 with a 12 volt heater and an extra pin.
The 6BG6G 6BG6GA and 6BD5GT were both TV sweep tubes derived from the 6L6GB. The 6BG6G, and 6BG6GA were 6L6GB's with a different pinout. The plate is brought out to the top cap to handle the kilovolt pulses seen in flyback operation.
The 6BD5GT is a 6L6GB with it's plate fins trimmed so it could be stuffed into a 6V6GT size package. It got a different pinout (same as the 6AV5's) to deal with the pin 3 (plate) to pin 2 (heater) arcing issue seen in some 6L6GC powered guitar amps. The 6BD5GT was only used in small TV's and is quite rare. I have two, both RCA's with black plates.....
Late in the era of tube manufacture some manufacturers, Especially Sylvania stuffed the glass with the biggest 6L6 variant of them all, the 7027A. I have seen 807's, 6L6GC's and 6BG6GA's all with 7027A guts in them. The 6BG6GA is the most common.
There is a pretty large evolutionary step between the 6L6 based sweep tubes and the 6BQ6GT and 6BQ6GA's. The 6BQ6 types got the big fat cathode with a 7.5 watt heater that the 6L6 types didn't have. It also got a screen grid with a finer pitch that was spaced a bit closer to the cathode. It is closer to a 6Y6 than a 6L6 in design. This step brought the first of the high purveyance tubes that could pull their plate down below 25 volts reducing dissipation in switching applications. The 6DQ6 got a bigger plate and more Gm. These tubes were what I learned on since most of my early tube amps were made with TV parts from the trash dump.