[Elecraft] KX3 & Chasing local HF noise sources
Jim Brown
jim at audiosystemsgroup.com
Fri May 2 03:39:14 EDT 2014
On 5/1/2014 11:14 PM, K8JHR wrote:
> My friend in Germany is making a serious study of common mode noise on
> OCF dipoles, and from his work I know you must bring the transmission
> line away at a 90 degree angle
It's MUCH more than that. OCF (off-center-fed) antennas (dipole implies
balance) are badly unbalanced, which places a very high common mode
voltage across a common mode choke because of their high degree of
imbalance, which tends to fry (destroy) the common mode choke with high
power.
The OCF antenna is an idea whose time is LONG past. In that long past
time, it offered a broadbanded solution that was "OK," but not great,
and in that long past time, noise was much less of a problem. Sadly,
noise is a BIG problem, and that makes OCF antennas a really bad idea.
73, Jim K9YC
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