[Elecraft] Problem Tuning K3

[Dan Presley]

Perhaps you could clarify what you meant by a modern OCF. What’s changed from the traditional model? Thanks. 

Dan Presley 503-701-3871
danpresley at me. com 
N7CQR at arrl.net


> On Nov 2, 2021, at 12:20, CUTTER DAVID via Elecraft <elecraft at mailman.qth.net> wrote:
> 
> 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
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