[Amps] [BULK]Re: [BULK]Re: cathode to ground in tetrode amp

[John Popelish]

Will Matney wrote:
  > On 1/30/06 at 8:37 PM John Popelish wrote:

>>Is it possible that these chokes and capacitors you mention are pars 
>>in a peaking circuit, to push the frequency response of the amplifier?
>>That would explain the high value parallel resistor (limiting the Q) 
>>and the cap on the tube side of the grid choke (to form part of a 
>>resonance, not a bypass).  I am afraid I have lost the original link 
>>to the schematic, so I can't easily look if this explanation is 
>>reasonable or silly.

 > The link is below. No, at the valuse there, it don't make sense
 > at all, or to me I can't see it. I've never seen anything
 > set up that way.
 >
 > http://www.angelfire.com/nb/ni4l/gu84b.html

Thanks for the link.  Here are some of the numbers:
The cathode LC resonance (just the 15 uH and .01 uF) produce an 
impedance peak at .41 MHz.
That would notch out frequencies near that (a little lower because of 
the cathode capacitance).
On the grid, the 22 uH and .001 uF would peak the grid voltage around 
1 MHz.  But the Q is very low because of the resistors in the grid 
circuit.

Very strange.  Anybody have a spice model for this tetrode?  I would 
love to frequency sweep this circuit and see what all is going on 
inside it.