Folks - Thread CLOSED. In the interest of relieving mail overload for those who are not interested in the argument on this topic, please take this off the list as it has been beaten to death.
73, Eric List moderator, COO, CFO and general playground monitor.. ;-) *elecraft.com <http://elecraft.com>* On Fri, Nov 5, 2021 at 11:13 AM Jim Brown <j...@audiosystemsgroup.com> wrote: > On 11/5/2021 4:24 AM, CUTTER DAVID via Elecraft wrote: > > As has been said on many occasions, there is no real difference between > a dipole fed in the middle and one fed off centre: as long as you can get > the current to run in the dipole by suitable matching and don't waste it > along the way, they are indistinguishable to the dx station. > > Statements like this ignore three fundamental facts. > > 1) Off-center fed antennas are noisy on receive, and you can't work who > you can't hear. This usually doesn't matter in the middle of nowhere, > but it matters a LOT in most of the developed world, where all of us are > surrounded by switch-mode power supplies (almost everything that plugs > into the wall), controllers for variable speed motors (HVAC systems and > other systems), grow lights, and solar systems. > > 2) When used on bands other than their half-wave length, horizontal > patterns are wildly variable, with multiple peaks and nulls at angles > predictable by antenna fundamentals. > > 3) It is impractical to EFFECTIVELY choke them at the feedpoint to kill > RX noise, the feedpoint being at the off-center point on the horizontal > wire, not down the matching section from the antenna, and it is also > impractical to EFFECTIVELY choke a feedline where it is severely > mismatched. Again, this doesn't matter in the middle of nowhere, but it > matters a LOT where most of us live. > > And it DOES matter to the DX station who calls you repeatedly and you > don't hear him, thanks to your RX noise. This has been happening to me a > lot on 60M FT8, where I'm licensed for 100W EIRP, and most of the rest > of the world is licensed for 15-25W. That power gives me a 6-8 dB > advantage, and stations I decode at -10 dB don't hear me! > > 73, Jim K9YC > > 73, Jim K9YC > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to eric.swa...@elecraft.com > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
