Topband: inverted L fed with coax (Tom Williams)

G3SED at aol.com G3SED at aol.com
Sat Jun 20 01:17:53 PDT 2009


In a message dated 19/06/2009 20:01:53 GMT Daylight Time,  
topband-request at contesting.com writes:

inverted  L fed with coax (Tom Williams)
A week ago I removed the UNUN and replaced it with a simple shunt coil.  My 
SWR is now 1.2:1 at the base and 1:1 back in the shack on 1830 kHz. It was  
nice to load the amplifer normally and get 1 kW output with only 3 W 
reflected!  The 2:1 SWR bandwidth in the shack is 60 kHz. 





Tom
I use exactly the  same method for feeding my inverted L  ( 66ft  vertical 
66ft horizontal ) with 140 1/4 wave radials. A shunt coil of  approximately 
the same dimensions as yours, I have never felt the need for an  UNUN feed. 
By tapping the coil it's easy to find the "sweet spot" for  1:1 SWR and once 
matched, works really well ( I have over 267 countries on  160 metres ).
 
73's
 
Mike G3SED 


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