Grid Current

If they glow, this is the place to be
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Paul Barker
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#61

Post by Paul Barker »

to recap the detracting variables of the connection in all these cases are:-

1/ We bias through the cathode and not through the grid, as we want no resistance at the grid. (Except a temporary 1 ohm resistor to facilitate grid current measurement for data collection which must be removed after curiosity satisfied) this means the valve quiescent DC operating point must be negatively biased.

2/ This sets us up to using an interstage of the DC resistance which facilitates 1/.

3/ The Grounded Grid needs a low impedance drive. The parallel driver arrangement shown above is viable with an impedance ratio of 1:2.5. but we may find that all driver arrangements would be better connected as the 300b diagram. It is simply a matter of where you put the Interstage transformer primary and how that is connected as to what the imedance ratio turns out to be. remember the GG presents (Load impedance + Internal impedance)/(mu+1) to the driver.

1/ has been my dominating consideration and that is why the valves I have suggested for the Danbury Interstage are presented here. for a different interstage, think again.

But the distraction of trying to obtain some gain from the driver may have caused me to compromise 3/. It may be best to connect all of the drivers as CF's. Though that puts is in need of either a medium mu cascade or a cascode voltage gain stage or a pentode into a Cf is viable or one of the many popular single stage voltage gain options which did the rounds a while back. you know who you are.

Yes I am up early in a hotel room which has a fekin air to air inverter (read awake all night with a fan blowing air at face as they mounted the feker beside bed, but insufficient bedding to stay warm with it turned off).

I always thought the air to air heat pumps were a good idea but now I have experienced one, I can advise you who live off the natural gas grid to save up every penny for a air to water or ground to water one. It is just not natural to blow air around inside the house as a form of heat. YUK!! I suppose by the end of the week I will have managed some sleap.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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