Topband: Nesting of four squares
daraymond at iowatelecom.net
Wed Dec 3 20:59:23 EST 2014
For about a decade I used a K8UR/bent dipole four square array on 80m. The array was supported from the 120' guy ring of my rotating tower and was a great performer. Several years ago I took it down, mainly for some environmental (no not global warming) and logistical reasons, and decided to try a ground mounted four square array nested inside my 160m ground mounted four square array. The ground mounted 160m array wire elements use standard spacing and are supported by a 190' tower using catenary ropes. The 80m ground mounted elements are also wire construction and supported by catenary ropes. Both arrays share a large, common ground radial system.
I had read in the Comtek hybrid instructions that nesting of 160m and 80m arrays was not a good approach but thought I might try it anyway. While the array actually has some decent F/B (maybe 16 db or so) it's a pathetic performer particularly on low angle signals. Signals that are several S units in strength at stations within 200 or 300 miles of me are so weak as to be frequently non-copyable, or marginal copy at best. I'm assuming the half wave 160m elements in close proximity are the problem.
I have not yet attempted yet to ground the 160m elements at the feed point in such a way that I could do a quick A/B test. . .i.e., with and without the elements grounded. The array is about 900' feet away. I do have some extra conductors I could use to pull up four relays to ground the 160m element when I want to operate 80m. If I were to do this does anyone have a recommendation of a suitable sealed DC relay? The voltage at the feed point will not be huge but the contacts would need to be fairly robust to take occasional lightning transients.
My question is this. . .will grounding the 160m elements when I want to operate 80m really solve the problem or am I better off to return to the previously successful K8UR/bent dipole config that would be located on a distant tower (abt 800' away)???
Greetings of the season and 73 to all. . . Dave, W0FLS
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