[Amps] trying to understand 1296 cavity amp

[TexasRF at aol.com]

Gary,
Without getting too deep into cavity theory, the rf is generated between  
the plate and grid in that tube. The rf flows on the cavity inner surfaces 
only.  The rf will not pass through any of the metal parts.
 
Following this reasoning, any rf present at the plate flows from the tube  
contact ring into the plate bypass fingerstock and out and on to the inner  
surface of the bypass plate. At this point, the rf sees a very low impedance 
and  exits the bypass plate and on to the inner surface of the cavity upper 
wall. The  rf continues on to the outer wall of the cavity and sees a short 
circuit  there. The short circuit causes a phase shift of 180 degrees and 
sends the rf  back toward the tube in reverse order from above.
 
When every thing is in resonance, the returning energy is in phase at the  
tube plate connection.
 
The same action occurs on the lower side of the cavity from the grid to the 
 cavity wall except there is no bypass capacitor plate in the rf flow path.
 
There is heavy coupling between the upper and lower cavity walls as they  
are very close in terms of wavelengths.
 
The concept of ground essentially disappears inside the cavity. There is rf 
 everywhere inside and ground is meaningless. Also, the action performs a 
balun  function perfectly so that the output coax, which does have a ground 
reference,  can couple to the rf inside the cavity.
 
There is a standing wave inside the cavity due to the short at the outer  
wall this is nearly infinite. The loss in the cavity is the limiting factor 
in  this vswr. The inherent high Q of cavities is related to this high vswr.
 
Pretty cool huh?
 
73,
Gerald K5GW
 
In a message dated 11/20/2009 9:48:31 A.M. Central Standard Time,  
gpatterson53 at hotmail.com writes:



I have a n6ca 2c39 1296 cavity amp and have trouble  understanding how it 
works.  The 2c39 plate has a large teflon sheet  capacitor to ground.  I dont 
understand how any rf gets into the cavity  when the plate is dead shorted 
with this capacitor.  any  help?



gary

w4af

_________________________________________________________________
Hotmail:  Trusted email with powerful SPAM  protection.
http://clk.atdmt.com/GBL/go/177141665/direct/01/
_______________________________________________
Amps  mailing  list
Amps at contesting.com
http://lists.contesting.com/mailman/listinfo/amps