[Elecraft] Problem Tuning K3

Jim Brown jim at audiosystemsgroup.com
Tue Nov 2 15:09:29 EDT 2021


On 11/2/2021 11:50 AM, CUTTER DAVID wrote:
> Don't stay stuck in the past: not all ocf dipoles are created equal.
> With properly designed transformers and chokes, the common mode current can be tamed to perfectly decent levels.

I suspect you don't understand the physics of the problem. OCF antennas 
are a yesterday's approach to multiband antennas. They are a recipe for 
RX noise and RF in the shack. The concept was developed decades ago, 
when there was far less noise than there is today. It's possible to fool 
yourself that it's working fine, but you can't hear very well, so you 
miss stations calling you.

I run legal limit on FT8 for weak signal work on 6M and difficult paths 
on 160M (EU from California) into resonant antennas that are choked and 
fed with RG8 or RG11, and I regularly get signal reports 15-20 dB worse 
than I give. Since signal reports on FT8 are signal to noise, that means 
the other station can't hear.

73, Jim K9YC






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