[Amps] Checking Plate Choke resonance

[Bill, W6WRT]

ORIGINAL MESSAGE:

On Sat, 10 Oct 2009 11:24:48 -0400, "rich ferguson" <n2xqm at cox.net> wrote:

>>> Does anyone know how to check A plate choke for resonances using a vector network analyzer (VNA).  
>
>73's Rich N2XQM

REPLY:

Sweep the choke across the planned operating frequencies and watch for any drop
or rise in impedance at particular frequencies. As a general rule the impedance
of the choke should be about ten times the plate load impedance or more. When
you see a sharp rise to near-imfinite impedance you have a parallel resonance.
When you see a sharp drop to near-zero impedance you have a series resonance. 

Neither resonance is harmful provided it is well outside the ham bands. All
chokes have resonances; the trick is to stay away from those frequencies. 

73, Bill W6WRT