Thanks for your answer and suggestions George, I hope not to have upset you.
If so, I really apologize.
My work implies travelling alot (except last two years), and this obliged me to simulate more than solder as I was used when younger. Beginning of 2022 I should have again a stable workbench with speakers, a signal generator and an oscilloscope to balance again the simulation/build ratio.
If so, I really apologize.
My work implies travelling alot (except last two years), and this obliged me to simulate more than solder as I was used when younger. Beginning of 2022 I should have again a stable workbench with speakers, a signal generator and an oscilloscope to balance again the simulation/build ratio.
No, I'm not upset. I'm just trying to point out why I can't always answer posts, email, and PM's.
First priority always goes to supporting my designs. Sometimes that's a full time job. Audio amp and music synthesizer design concepts, circuits and thoughts come in second. There are many more electronics things that I can't even keep up with any more.
I'm now nearly 70 years old, and these past two years have led me to realize that I have far more "projects" than life expectancy left, as many of my friends have left this world in the last two years, including my tube supplier. This means that some project prioritization is in order, as well as some serious "mess management."
I originally got into electronics because my parents gave me an electric guitar at age 7, but no amplifier, because they didn't want to hear it. Making music was my first love, and all of my projects involved guitar amps or music synthesizers. Sadly the music making part has been neglected for about 50 years due to the usual, wife, kids, job...... I plan to get back to it while I still can, so my time spent with audio amplifiers in general will be gradually reduced.
I plan to take the UNSET concept forward as far as I can. All will be shared here, and I hope that people here, including yourself can grab it and run with it. Will I ever build the push pull kilowatt amp based on UNSET technology? I don't know. I have talked about it for over 10 years, but never built it. Do I need a 1 KW tube amp? No, but it would be cool.
I will be putting stuff including tubes and parts on the forum Swap Meet and Ebay sometime in the near future. It is a means of "stuff reduction" not an indication that I have left the hobby.
George’s discussion of OTs for UNSET
I had just read George’s recent post on the Transcendar thread, and thought it would be of interest to those who follow the developments of the UNSET design.
For his current thoughts on Hammond, Edcor, Toroidy and other output transformers check here:
https://www.diyaudio.com/forums/tubes-valves/377360-transcendar-3.html#post6796691
I had just read George’s recent post on the Transcendar thread, and thought it would be of interest to those who follow the developments of the UNSET design.
For his current thoughts on Hammond, Edcor, Toroidy and other output transformers check here:
https://www.diyaudio.com/forums/tubes-valves/377360-transcendar-3.html#post6796691
Unfortunately, most of my accurate highish power curve tracing was done manually with power supplies, meters and Microsoft Excel. I have an old Vacutrace but it can't do positive grid (gate) voltage so I experimented with workarounds. The best solution I came up with was an opamp inverter circuit which works but is limited to about +15 volts with common opamps. The Vacutrace works with an oscilloscope, and usable results require an analog scope, so only one of my three scopes works right with it. It is also limited to 380 volts and 20 watts total on the plate. It was a great learning tool in the early UNSET / CED development which was mostly done on medium size tubes like the 6W6 and 6GF5 because I have lots of each and don't get upset when I blow one up.
This is a set of "curves" I made for the 6LW6 tube that goes a bit beyond the data sheet curves. Yes, that tube ate over 600 watts and still works today. Also pictured is a CED (compound electron device, or UNSET pair). This is a 24 watt tube paired with a p-fet and tested to about 100 watts. In both cases the button was pressed just long enough to read the current meter, maybe 1/2 second.
This is a set of "curves" I made for the 6LW6 tube that goes a bit beyond the data sheet curves. Yes, that tube ate over 600 watts and still works today. Also pictured is a CED (compound electron device, or UNSET pair). This is a 24 watt tube paired with a p-fet and tested to about 100 watts. In both cases the button was pressed just long enough to read the current meter, maybe 1/2 second.
Attachments
I don't know much about the micro trace, but plate power limitations are another thing to look into. You don't need, or want to test a tube at 100 watts for a long period of time, but short pulses into regions where you might want to test make sense. I originally built a breadboard with a source and sink fet on each grid and the cathode. Some of the combinations I played with before arriving at the CED had linearity only over a narrow operating range, hence me testing things far beyond where they will be used.