Thanks for sharing the test results.
New measurement results for the PP self inverting output stage, this time with cathode current increased to force Class A operation. The results are much better.🙂
But still looks like a proper phase inverter is a better choice.
The IMD tests are based on equal signals at 1.5 & 2 KHz.
But still looks like a proper phase inverter is a better choice.
The IMD tests are based on equal signals at 1.5 & 2 KHz.
Still not too good, but at least it's not as bad...
Not that I'm considering a build utilizing self split, but do you think a stiffer CCS like an NPN or depletion Mosfet cascode would improve things?
Also, my gut feeling is that this may work best with higher gm tubes...
Not that I'm considering a build utilizing self split, but do you think a stiffer CCS like an NPN or depletion Mosfet cascode would improve things?
Also, my gut feeling is that this may work best with higher gm tubes...
In the earlier work (reported three posts up from here) I found that an NFET vers (IRF840) did not work as well as the LM317 or Hammond 5H choke, even when returned to -22.4V. It didn't seem to make sense to try again.
Those I did try were significantly better.🙂
At some future time I'll try a real phase inverter on this for comparison.
Those I did try were significantly better.🙂
At some future time I'll try a real phase inverter on this for comparison.
Do you have EL84 to try? I suspect higher mu and gm may improve things. Then it's a trivial thing to DC couple a fet to the driver tube to try a concertina phase inverter with minimal changes at the drive voltages required.
I would probably want to try a ring-of-two bipolar cascode, or a cascoded DN2540 depletion set as a CCS, should be an order of magnitude better than a single fet or the 317.
I would probably want to try a ring-of-two bipolar cascode, or a cascoded DN2540 depletion set as a CCS, should be an order of magnitude better than a single fet or the 317.
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