[TowerTalk] Remote Tuner with ZS66BKW or OCF Dipole

[Jim Brown]

Several thoughts. First, the open wire matching section is part of the 
antenna, and any noise pickup on it will be coupled to the antenna and 
show up in the receiver. Second, feeding any antenna off center greatly 
increases the common mode current and voltage, which increases the noise 
pickup. Third, antennas like this cannot be choked because the common 
mode voltage is too high AND the SWR is too high, both of which are 
likely to fry the common mode choke (the real name for a "current 
balun") if you're running much power.

These antennas were cooked up half a century ago when hams had never 
really run into serious RX noise and had never heard of common mode 
chokes.  Yes, it is possible to make a dipole like this "work" on all 
bands, but as N6BT has shown by working all continents on a light bulb, 
almost anything "works." The questions are "how well does it work," and 
"are there other simple antennas that work better."  The answer to the 
first is "not very well," and to the second, a well designed vertical on 
a roof or one or more multiband resonant fan dipoles  will outperform 
it.  The vertical may be equally noisy, but the fan dipoles will be much 
quieter because they can be effectively choked.

73, Jim K9YC

On Sun,7/26/2015 8:07 PM, Phil Coley wrote:
> I have read a lot on these antennas from post on the web on their "pros & cons". There isa lot of info on the web regarding loss with certain types of coax, types of ladder lines, varyinglengths for better band coverage (OCF), etc.I know that many G5RV/ZS6BKW versions say that at least 70' of coax must be used for the antenna to workproperly. And the SWR on some of the bands with both the G5RV/ZS6BKW & OCF have an SWR that is toohigh and losses would make the band "non-useable" due to this.Has anyone experimented with using a remote Tuner (LDG, MFJ, etc.) near the antenna to reduce losses inthe coax to the rig?  What would be the results in say, using a remote tuner on a ZS6BKW after the ladder lineconversion to a SO239 for coax? The need of an balun/CMC choke would probably be helpful & maybe a shortrun of coax before connecting to the tuner? If a low SWR is obtained at the remote tuner, my thinking is the loss on the coax run to the shack would be verylow. This would be helpful especially on a long coax run. Am I "out in left field" on my thinking? Is this a workablesituation or are there factors I am not seeing?Phil K4MPE
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