RadioBanter - View Single Post - 2 baluns on doublet feedline to overcome impedance changes?

Cecil Moore[_2_] · July 6th 09, 07:30 PM posted to rec.radio.amateur.antenna

wrote:
one thing i neglected to mention is that the rig is grounded;
according to the roy lewallen document i referred to, the ground
connection causes imbalance, regardless of the ladder line;

A grounded rig doesn't necessarily cause imbalance
in balanced systems. For instance, a primary/secondary
isolated transformer will cancel the common-mode
components at the transformer secondary windings.
(Such a transformer works best when optimized for
a single band.)

i'm also aware of the link-coupled transmatch;

Unfortunately, the secondary winding in the Johnson
Matchbox is referenced to ground through the loading
capacitors. It appears the Johnson designers didn't
consider common-mode problems.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com