THANK YOU to all who posted or privately emailed pointers! My CC dipole is
ready to go in the air. Here are the things I've learned from this
experience with the help of Tower Talk:
1. The MFJ 969 Antenna Instrument is remarkably consistent with on
air SWR measurement, plus it provides much more information. Showing
resistance as well as reactance, coax loss, and SWR. It is affected by
coupling to ground just like the transmitted signal. The two SWR curves
match almost exactly. (makes sense, but I couldn't be sure until I saw it
with my own eyes.)
2. Trying to adjust a loaded antenna element without the
instructions is very difficult! Once Brian furnished the correct numbers
things came together fairly quickly.
3. The tuned element now has a nice smooth curve with it's dip from
7.025 to 7.125. The dip is to 1.45:1 essentially textbook for a dipole
centerfed with 50 ohm cable. At the ends of the dip it curves upward
steeply to 2:1 within 50 kHz. I am confident that this curve will shift
upward in frequency to my desired point of coverage as well as maintaining
the 200 kHz bandwidth it should cover, once it is raised into operating
position.
4. I went with the good old Collins type/coax balun. I used 10
turns of RG213 around 5" form then held together by nylon zip strips and
reinforced by "88" Tape.
So again thanks to all of u who helped, and I hope this helps someone else
make sense out of some question.
By the way, like Peter, I too was looking forward to Kevins antenna
saga. I doubt we're all too busy to give him some advice. It may seem
tiresome to feel u r asked to repeat information, but if we stop repeating
it we start forgetting it. Plus, as Hams we need fresh inquisitive people
to go where lots of others have gone before (sorry about the Star Trek
pun). Without new hams, our hobby will disappear with our generation (the
baby boomers and older). The more that new hams learn-- the more value
they will be to the hobby.
73 de Frank kb8xu
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