Hi Michael,
Yes, thats basically it. I didn't bother with the source follower on the input, just the resistor r2, since the curve tracer has a low Z step generator for testing bipolars too.
-------------------------------------
And speaking of 12AT7, here it is:
Yes, thats basically it. I didn't bother with the source follower on the input, just the resistor r2, since the curve tracer has a low Z step generator for testing bipolars too.
-------------------------------------
And speaking of 12AT7, here it is:
Attachments
Last edited:
Nice toy indeed!
Speaking of 12AT7, I guess 6BQ6 will show similar results, on much higher currents. No?
A now, a "triode" that eats 300B's for breakfast. Awesome linearity. 40W $1 each. Plentiful. (I have a box of 100) I'm not saying anymore.
OK, me lost the track of things... (easy with a dizzy head like mine)... so are those curves in post #32 the GU50 or the FET sitting on a diode?
J.
That was the FET (FQP1N50) setting on a damper diode (6DN3) with Schade feedback from drain to gate. Like Michael drew. The Schading gives it "plate" resistance and the diode gives it nice 3/2 power law curves like a triode. One might also be able to use a Schaded and degenerated Mosfet down bottom, in place of the diode, to give it square law curves which would look more like a power triode. Putting just a resistor down bottom makes for tilted straight line curves.
Tomorrow, our heads may really spin when I post curves for the Anti-triode.
Tomorrow, our heads may really spin when I post curves for the Anti-triode.
Last edited:
Smoking-amp, I envy you your toy I wish I had something like this si I could check out my tubes but I guess they are way out of my $$$ league ...
Is there any chance you could post curves for an unknown element with triodish characteristics - be it a tube or some kind of SS contraption but not combination thereof - where it isn't immediately obvious which kind of element we're looking at (that is: curves should not be crashing into Ia = 0 line like they do in your pic of schaded FET or sweeping leftwards way above the axis like they do in pictures of those very nonlinear tubes) ? Don't tell us which element it is, don't give hints (at least not right away), just post the measurement scale along with the pic.
Much obliged !
Edit: hey, I just had an idea - could you make that 5 pictures so we can turn it into a forum contest ? 5 pictures, everybody gets one shot at guessing (tube or SS ?), say one week to post their answer, then the contest closes and you announce the correct answers ?
I wish I had something like this si I could check out my tubes but I guess they are way out of my $$$ league ...Is there any chance you could post curves for an unknown element with triodish characteristics - be it a tube or some kind of SS contraption but not combination thereof - where it isn't immediately obvious which kind of element we're looking at (that is: curves should not be crashing into Ia = 0 line like they do in your pic of schaded FET or sweeping leftwards way above the axis like they do in pictures of those very nonlinear tubes) ? Don't tell us which element it is, don't give hints (at least not right away), just post the measurement scale along with the pic.
Much obliged !
Edit: hey, I just had an idea - could you make that 5 pictures so we can turn it into a forum contest ? 5 pictures, everybody gets one shot at guessing (tube or SS ?), say one week to post their answer, then the contest closes and you announce the correct answers ?
Last edited:
RE: Arnulf
The curve tracer cost me $500 on Ebay, a Tek 576. Which I had to mod the step generator amplifier and its power supply to provide higher step voltage ranges for tubes. It can do up to a 200 V step range for screen drive plots now. I bought a Tek 577 around 5 years ago, after the dot.com bust, for $150. I have it loaned out to a friend, but when I get it back (if it still works) I am going to mod it for tube stepping also. Seemed like the ususal tube testers were in the same $ range on Ebay.
A lot of triodes look pretty similar on the tracer except maybe for different step voltages or V and I ranges, unless they are stand out non-linear ones. Here are a few device plots, usually with some distinguishing features to give some hint. OH, I likely grossly exceeded the max Watt diss. on some of these to get a more complete curve set.
A: 200V /div. horizontal scale, 10 mA / div vertical scale
C: DHT 50 V/div horiz. , 2 mA/div vert.
D: section #1 50V/div horiz., 1 mA/div vert.
F: section #2 50V/div horiz., 10 mA/div vert.
(sections #1 and #2 above are from the same bottle)
The curve tracer cost me $500 on Ebay, a Tek 576. Which I had to mod the step generator amplifier and its power supply to provide higher step voltage ranges for tubes. It can do up to a 200 V step range for screen drive plots now. I bought a Tek 577 around 5 years ago, after the dot.com bust, for $150. I have it loaned out to a friend, but when I get it back (if it still works) I am going to mod it for tube stepping also. Seemed like the ususal tube testers were in the same $ range on Ebay.
A lot of triodes look pretty similar on the tracer except maybe for different step voltages or V and I ranges, unless they are stand out non-linear ones. Here are a few device plots, usually with some distinguishing features to give some hint. OH, I likely grossly exceeded the max Watt diss. on some of these to get a more complete curve set.
A: 200V /div. horizontal scale, 10 mA / div vertical scale
C: DHT 50 V/div horiz. , 2 mA/div vert.
D: section #1 50V/div horiz., 1 mA/div vert.
F: section #2 50V/div horiz., 10 mA/div vert.
(sections #1 and #2 above are from the same bottle)
Attachments
Last edited:
Here is another tube, pentode + ?.
G: pentode mode 50V/div horiz., 20 mA/div vert., g2 at 120 V
G2: triode configured 20V/div horiz, 10 mA/div vert.
G3: the other section 1 V/div horiz., 20 mA/div vert.
Notice how the really ugly pentode curves turn into rather nice triode curves. Also, the data sheets for this tube I have seen do not show the nasties in the pentode curves near the knees. But most of the samples I have tested do have this to some extent.
G: pentode mode 50V/div horiz., 20 mA/div vert., g2 at 120 V
G2: triode configured 20V/div horiz, 10 mA/div vert.
G3: the other section 1 V/div horiz., 20 mA/div vert.
Notice how the really ugly pentode curves turn into rather nice triode curves. Also, the data sheets for this tube I have seen do not show the nasties in the pentode curves near the knees. But most of the samples I have tested do have this to some extent.
Attachments
Last edited:
Would you by any chance happen to have 1Zh37B (Russian directly heated battery-powered submini pentode with internals the likes of which I have never seen before - there are no grids inside inside that tube, all electrodes appear to be solid) you could hook up as well in various modes ? That thing has two "g1"s which give it different characteristics depending on whether one or both are used.
There are grids there, but they are made of the same rods as other electrodes.
From Google dictionary:
A grid is something which is in a pattern of straight lines that cross over each other, forming squares. On maps the grid is used to help you find a particular thing or place. N-COUNT
It doesn't contain any wire grids. It uses solid rods (as some sort of reflectors ?). Anyway, it supposedly has interesting characteristic curves, not at all described in the datasheet.
Grids in tubes are called such a way because they were initially made as grids. In modern tubes, since 1930'th, they are just wires on frames. No squares.
Interesting characteristic curves are non-linear, because the tube was designed and manufactured for frequency converters in military radio equipment.
Interesting characteristic curves are non-linear, because the tube was designed and manufactured for frequency converters in military radio equipment.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.