[Top] [All Lists]

[AMPS] Henry 2kd classic

To: <>
Subject: [AMPS] Henry 2kd classic
From: (2)
Date: Wed, 12 Sep 2001 09:57:16 -0700
>> Hmmm, if there are no good rules of thumb and no peak current/energy
>> ratings for anode supply components, how does one go about sizing
>> the glitch resistor? 
>I'd just make it as big as I reasonably could, depending on plate
>current. There really isn't any reason to dissipate more than a 
>percent of the output power in the resistor from I^2 R losses, and we
>don't want to noticeably reduce HV regulation.
>> BTW, speaking of grid components, how come Drake grounds the grids
>> on the L-7 thru a parallel combination of RF chokes and capacitors? 
>That is a mistake that was promoted by Bill Orr (now SK). Bill 
>talked Heathkit into doing it also, as well as other companies. The
>original idea came from the 30S1 where it worked quite well. The 
>is you form a capacitive voltage divider between the cathode and
>ground and tap the grid up on that divider to make the amplifier less
>sensitive to drive power.
> It works perfectly in the 30S1 because it is a grounded-grid tetrode
>that draws no grid current. The screen shields the input and output,
>and since the divider is lightly loaded by a very high grid impedance
>the division is the same from band-to-band.
>The moment the 30S1 draws grid current, the impedance between 
>cathode and grid drops like a rock and the grid is "tied" to the
>cathode. While this produces distortion when grid current appears, 
>does prevent hurting the tube from excessive grid current. It also
>increases driving power requirements. So it was an excellent idea in
>the 30S1 because it was an AB1 TETrode!
>The results are different in a triode, because there is no shield
>between the anode and cathode other than the control grid. Also, since
>the tubes generally draw considerable peak grid current the grid
>voltage waddles all over the place on SSB. 

//  4v out of 75v of G-K drive is "all over the place", Tom?

> ...

-  R. L. Measures, 805.386.3734, AG6K,  

FAQ on WWW:     
Administrative requests:

<Prev in Thread] Current Thread [Next in Thread>