Concertina phase inverter with LED bias - is this completely wrong? - Page 2

richwalters · 05:37 PM

Rule of thumb...I aim for all voltages in a cathode follower to be a third each of the B+. My schematic I commonly use.

.....in concertina I don't bother with split cathode resistor.
solong it's DC bias strapped to preceeding stage which is in control. I've always assumed since the stage operates with fantastic neg feedback, the concertina distortion is already extremely low or an be ignored if Correctly operated..

The B+ is approx 360V which is off the pic.
richy

nlinus · 16th September 2012, 07:24 PM

Quote:

Originally Posted by richwalters

Rule of thumb...I aim for all voltages in a cathode follower to be a third each of the B+. My schematic I commonly use.

Well, that's not exactly the case with my current values. A B+ of 300V and anode/cathode resistors on 3.4k each.
At 15mA, that would result in a Vak (voltage drop anode to cathode) of 198V.

I don't know if I misinterpreted the values in the datasheet.
Ua is set to 200V for triode mode.

richwalters · 16th September 2012, 08:17 PM

C3g is a high gm pentode.. your drawing shows g1 to cathode and you are using the screen as signal input: Correct ? That changes my equational picture somewhat.

nlinus · 16th September 2012, 09:17 PM

It shows (or at least it should show) g2 to anode, g3 to cathode and g1 (not marked) as signal input.

16th September 2012, 09:17 PM	#14
nlinus diyAudio Member Join Date: Jan 2004 Location: Jämtland	It shows (or at least it should show) g2 to anode, g3 to cathode and g1 (not marked) as signal input. __________________ ---------------------------------- One of my other projects: Svarthålet Racing

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16th September 2012, 08:17 PM	#13
richwalters diyAudio Member Join Date: Sep 2003 Location: Alps:Tube amp designs over 150W, SMPS guru.	C3g is a high gm pentode.. your drawing shows g1 to cathode and you are using the screen as signal input: Correct ? That changes my equational picture somewhat.