[TowerTalk] UL listed protector for ladder line

[Paul Christensen]

>"Besides it being easier to find a certified protector for 50 ohm coax,  a resonant dipole or a fan dipole fed with coax will have a nicer pattern and perform better than the W7FG dipole with ladder line on non-resonant frequencies. John KK9A"

Performance of the W7FG dipole (aka Dipole-Doublet and CF Zepp) is relative, as shown by Cebik in the PDF attachment.  The radiation pattern will be more complex and less predictable than on resonant bands but it will produce gain and nulls in various directions over a resonant dipole -- sometimes to an advantage, sometimes not.  

Given the flexibility of running coax to an outside-mounted ATU, then 600-ohm open feeders to the antenna, I find that the benefit of this configuration outweighs its disadvantages when compared to multiple resonant dipoles.  With a 136 ft. dipole-doublet, the pattern mostly replicates a resonant dipole on 80m and 40m where I'd rather not have the many lobes and deep nulls that occur when using the antenna on the upper bands.  

In this configuration, a certified Z50 surge protector can still be placed on the coax at the outside-mounted ATU, or at the outside point of premises entry, depending on the local code requirement.  If at the ATU, the protector's ground stud will require connection to the AC mains bonding point, generally not to exceed 20 ft. in length.  The NEC goes into additional detail when it comes to longer bonding lengths.  For that reason, placement at the premises entry point is probably easiest, especially if it's close to the AC mains bonding point.  

Paul, W9AC