Hello folks:
I was looking at my tube collection and checking out the the discussion about the 38he7 being able to be split into an 15Watt pentode and a diode. If the heater is wired to pin 10 and 12 the diode is left blank. The pentode goes from 10W dissipation to perhaps 15W or so. So I decided to check out the 33gy7a and found a similar thing. This time it is pin7 and pin12 to lite the pentode and I think the pentode is a 6ge5 which is a 6dq6b @ 18W. This tube may be a bit of a sleeper. More research must be done to confirm.
Interesting possibility when tube still only costs a buck or two.
I was looking at my tube collection and checking out the the discussion about the 38he7 being able to be split into an 15Watt pentode and a diode. If the heater is wired to pin 10 and 12 the diode is left blank. The pentode goes from 10W dissipation to perhaps 15W or so. So I decided to check out the 33gy7a and found a similar thing. This time it is pin7 and pin12 to lite the pentode and I think the pentode is a 6ge5 which is a 6dq6b @ 18W. This tube may be a bit of a sleeper. More research must be done to confirm.
Interesting possibility when tube still only costs a buck or two.
Looking at the 33GY7 data sheet, it looks a little "light weight" compared to the 38HE7, which looks more like a de-rated 6GE5/6DQ6B. 38HE7 pentode curves are nicely spaced too, compared to the others.
33GY7 looks more like a 6GF7, which looks like a 6GE5 with a "cut down" plates stuck in a smaller bottle.
jeff
33GY7 looks more like a 6GF7, which looks like a 6GE5 with a "cut down" plates stuck in a smaller bottle.
jeff
Last edited:
Was this common practice for US tube manufacturers to fit both the line power tube and it's damper into the same, single ended bottle? Here in Europe we're accustomed to two separate tubes, each with a top cap...
Best regards!
Best regards!
This was mainly a compactron thing in US, AUS, JP.
...HQ7, GT7, GY7, HE7, HK7, .... 450mA series heater string
The heater tab seems to be present on all of them but is never documented and labelled i.c. in the ds.
The GY7 has a 6GE5 pentode according to this overview:
https://frank.pocnet.net/other/Compactrons/CompactronSurvey.html
...HQ7, GT7, GY7, HE7, HK7, .... 450mA series heater string
The heater tab seems to be present on all of them but is never documented and labelled i.c. in the ds.
The GY7 has a 6GE5 pentode according to this overview:
https://frank.pocnet.net/other/Compactrons/CompactronSurvey.html
Last edited:
As the semiconductor slowly crept into electronic devices that were built with tubes there was a period of time where hybrid TV sets were made. GE used the term Compactron to describe tubes that had two and three sections built into a 12 pin package. Near the end of the tube TV set there were some "portable" TV sets with as few as 4 tubes. One of the consolidations was the stuffing of the horizontal (line) output tube and the damper diode into a single fat bottle. These only existed for a few years and were used in TV sets in the 19 inch and down size. Full size color TV's still used separate tubes. The 33GY7 and 38HE7 were the common flavors. There was a 53 volt version and a few others but I can't remember the numbers.
The 6GF5 is a shrunken 6GE5 with its plate "wings" clipped. Both were made with 6DQ6B guts. I stumbled upon the 6GF5 while digging through some tubes at the ESRC warehouse when I still lived in Florida. They were on the $1 list, and Stan said that even at that price, they did not sell. Many tube sellers have never heard of them, so they must not be common. Stan had about 600 of them, and someone grabbed 300+ in 2017. I bought a big box full for less than $1 each about 15 years ago. This led to an amp that made 80 WPC and some other interesting experiments. There is a little but LOUD guitar amp experiment going on that might use some of them.
I learned the hard way that some of the big horizontal sweep tubes have an undocumented heater tap labeled I.C. on pin 7. Stuffing a set of 35LR6 tubes into Pete's Engineer's Amp put plate voltage on to my heater circuit making the bypass caps explode. Not all 35LR6's have the tap, but the Sylvanias that I have do!
Attachments
Last edited:
good morning folks:
Thanks for all the comments. I guess my assumption was correct. I will have to do some experimenting as I have a few of these to play with.
Thanks for all the comments. I guess my assumption was correct. I will have to do some experimenting as I have a few of these to play with.
I have never actually experimented with the damper / output combo tubes, so I don't have much to go on here, but the vertical output / oscillator combos like the 6LU8 / 6LR8 tend to red plate first on the side of the output tube plate that faces the oscillator triode., even with zero plate current in the oscillator. There is no way to disable the heater in the oscillator though.
Those "9 watt" 6GF5's will eat between 15 and 25 watts before showing color depending on how well they were made. I picked 4 good ones for the 80 watt amp experiments.
