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From: Randy VE3 ARB
Date: 16 Apr 2002
Time: 21:20:35
Remote Name: 65.93.99.137
Will try to keep this short. Building a vertical 1/2 wave dipole using a de-tuning sleeve at 90 deg to dipole for decoupler which is then T'd on to a non conductive mast. Looks like an H with a long right side but the upper right part of the H missing. Coax exits sleeve with good radius for coax then ty-wrapped to mast and down.
Initial purpose of antenna is to hit my club's repeater on 2M, initial design frequency is 146.0 Mhz which will allow soom room in case I trim too short. Dipoles are 1/2" alu and sleeve is 1.25" alu. Coax in sleeve is RG58 spaced in the center of sleeve using non conductive spacers, terminating in a 259 connector about 4" out of sleeve, to which I connect the feed line.
Antenna measurements were done using my MFJ 259B analyzer (jeez, try getting that one by the wife!) while keeping measurement sessions the same each time. The antenna position, while not its final resting place was as close as I could get but with ease in putting up & down for trimming.
Measurements were done using RG58U as a feed line (ease of use) at 185.5" length. Final feed line is to be Beldon 9913.
After a couple of measure & trims I have these final numbers: 144.06 Mhz 1.2 SWR 59 R 10 X 145.05 1.3 65 3 146.04 1.3 67 0 147.10 1.3 64 9 148.06 1.3 60 15
Rather elated with these numbers, I thought maybe try 9913 feedline. Numbers I got are: 144.02 1.6 46 23 145.10 1.6 40 21 146.05 1.6 36 18 147.04 1.6 34 15 148.09 1.6 33 13
Both sets of numbers are good but I would like to know, is the differences in the coax causing this and the MFJ picking up on it, the different coax just confusing the MFJ and giving different readings or should I really care and just button it up and put it into service?
Randy VE3 ARB