[TowerTalk] RADIAL QUESTIONS

[Tom Osborne]

"Dick Green". wrote:> 
> So, I went back and forth, lengthening the antenna until the transceiver
> reported minimum SWR at 7.150. At this point, however, the MFJ reported
> minimum SWR was ocurring at 7.300! I ignored the MFJ's results and have been
> operating happily on 40M ever since (the antenna is very broad; the SWR
> hardly budges across the entire band.)

Hi Dick. I have a three element vertical aray here, and the run of coax 
to each element is about 50 feet and I do the switching and phasing 
inside the shack.  I have adjusted the antennas at the base of the 
vertials for as close to 1 to 1 as I can get. Usually about 1.6 to 1.8 to 
1.  I have an extensive radial field under all three also the 160 meter 
inverted L. They are just laying on the ground-all different lengths. I 
tied the hub of each antenna together so that each antenna is using all 
the radials.  It works very well.  I have found that the length of coax 
going from the swr bridge to the phase box makes a difference on the swr. 
 You might experiment with adding a length of coax from the swr meter to 
the line going to your antennas.  I've found that makes a big difference. 
 I have a switch box in the shack to switch the antennas and I 
experimented with the length of the coax going from the box to the swr 
meter till I got it the same as at the base of the antenna. You want to 
be sure the coax from each antenna is the same length though. I think if 
I put some kind of balun at the base of the vertical, it might keep the 
swr from changing.  Another thing I did was make a coil choke right where 
the coax came into the shack.  I had some problems with rf getting into 
stuff in the shack.  After I wound the chokes, I didn't have any more 
problems.  My antenna is swichable to 6 directions, and it sure has made 
40 meter operating more fun.  Good luck and you will surely enjoy those 
antennas. Merry Christmas
Tom W7WHY

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