Topband: Short Radials, Antenna Update: PART "TROIS"
gswynar at durham.net
Tue Oct 31 15:13:59 EST 2006
Good Day Everyone,
...And a very FB day it has been too for me here, indeed --- it pleases me to no end to announce that the 3rd & final inverted "L" of my tri-angular phased array is finally up and running(!) as of about one hour ago!
With grim determination I scaled the 50' tower here all by my lonesome, & laced rope through the pulley at that level --- it all went surprisingly quickly, and (happily) without incident...although I refused to look down even for a single solitary second. It was an easy matter from there (safe on the ground again) to hoist up the 170' wire that comprises the inverted "L"...
During my subsequent SWR trests, however, I came to realization that the series tuning capacitor at the base of my "L" was probably near half of what it should have been (I used a 100-pfd. air variable)...the antenna was resonant somewhere above 2100-KHz. I contemplated paralleling it with a "homebrewed" fixed capacitor cut from a few feet of open RG-58, but then decided against it: who knows what changing outside temperatures --- and high power operation --- might do to the dielectric of this "gimmick", and the thing's final capacitance...?
I'd already had more than my fill of mica & door knob caps changing values on me in my 2x813 amplifier iunder load, so I decided, instead, to simply install a second air variable capacitor (115 pfd.) in parallel with the first. A nice broad 1:1 SWR was achieved on 1.820-MHz with ease...
A quick rotation of the manual direction switching box verified that the system's SWR varies only minutely when going from one direction to another. I recall with the installation of my east "L" that its tuning capacitor was set at maximum to achieve a flat SWR response --- but it was just ABOVE my targetted 1.820-MHz design frequency. My suspicion is that this is the reason for the slight disparity in reflected power, & I've already targeted to-morrow for the installation of a second small air variable, to be placed in parallel with the existing one already in residence within its Folgers Coffee weatherproof container...
Hurry sundown --- I'm anxious to test the array out in the real world of DX. In the interim, I rotated the directivity control while monitoring 1580-KHz AM BC station CKDO some 10 miles, or so, to the west of me...there are DEFINITELY good things happening on receive!
Who'd have thought --- standing back and reviewing the lay-out from my front yard as I did when I was finished --- that lengths of wire, halyards, & ropes hung up in a bunch of trees & a tower could all look so beautiful...?! What a symphony. I guess one has to be a Radio Amateur to appreciate something like that...
See you in the pile-ups!
~73~ Eddy VE3CUI - VE3XZ
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