[Lowfer] Question on TX loop cap placement

[ToddRoberts2001 at aol.com]

In a message dated 11/13/2008 9:54:00 P.M. Eastern Standard Time,  
we0h at yahoo.com writes:

I would like to build a HF band TX loop. These loops are .1 wavelength  
of wire or copper pipe. Do you guys see any reason why the HF guys put  
the series resonating cap in the loop opposite of the feedpoint coupling  
transformer?
 
__________________________________________________________
 
Hi Mike,
The point of the loop opposite the tuning capacitor is the voltage  'null'
point of the loop. You can think of it as the center-tap point of a  balanced 
loop.
Since many hams use coax cable feed to a remote loop
the coax shield can be grounded at the null point of the loop. This  will
 safety-ground the loop and not upset the pattern of the loop.
 
Also do not limit your self to a .1 wavelength size loop. A small  
transmitting
loop can be up to 1/3 wavelength. Most folks use up to a 1/4 wavelength 
circumference loop for high efficiency at the band of interest. Make  the 
loop 
as large as possible without going past self-resonance for best efficiency 
and minimum tuning capacity needed.
 
73 - Todd WD4NGG
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