[Elecraft] Problem Tuning K3

[CUTTER DAVID]

Hi Jim

Not many folks have the space or ability to put up a full set of resonant dipoles.  The MODERN off centre fed dipole is as good as you'll get any multiband antenna and for the most part will not need a separate antenna match box.  

I suggest you measure the common mode current on a decent ocf dipole and see for yourself. Great progress has been made in the last few years and, yes I use your cookbook.  

David G3UNA

 
> On 02 November 2021 at 19:09 Jim Brown <jim at audiosystemsgroup.com> wrote:
> 
> 
> 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