This is why I move the wires to the outside of the pvc. I have at least 2"
of separation between wires now. In addition to the ability to tune up on
40m w/o transmatch have noticed that generally speaking it tunes much easier
on each band when use the ant tuner. I bet the wires, when strung on the
inside, were crossing over or too close to each other. In any event, my
next step is to obtain an analyzer and move the alligator clips around on
the load coil. Once this beast is functioning, I am going to write up a
short how-to for the web site. This pvc actually looks okay in the
backyard.
-=Jon
"Mark Keith" wrote in message
om...
"J. Laub" wrote in message
...
I'd like to construct a 15m vert that does not require use of my MFJ
Versa Tuner II. Portability. I started over this afternoon on a new
vertical using plans from a web site.
WIRING:
I've suspended an 11'1" #12 wire for 15 inside some pvc. (While I was
at it I also suspended a 16'5" #12 wire inside the same piping for 20m.)
That may be half of your problem. #1, the PVC may be effecting the
overall length of the wire a bit. #2, if you have another vertical
wire right next to it, they will couple and all bets are off. You are
not tuning on 15 because with that extra 20m wire next to it, you are
now too long I bet.
RADIALS:
I've got six underground radials, 2 @ 11' and 4 @ 5-1/2"
Another comment...Ground mounting a 15 or 20 meter vertical is never
going to be that great a performer. You would be much better off with
something elevated off the ground. Of course, I realize this may not
be possible in your case.
FEEDER & CONNECT POINT:
Using 52ohm RG58 (the thin stuff) to feed into a female coax chassis
mount at base of system. I have a small (maybe 4") of line from the
center of the chassis mount leading to the connection point bolt/wing
nut for each/either wire. This wire is 4" and I suspect this 4" may
cause some electrical lengthening right?
Right...
If it does, I'm over on
measurements for each. errr....
errrr....Yep, that, and the 20m wire, and you are probably way too
long...
Other than this possible lengthening, I cannot think of what else to do.
In short, I should probably borrow a dip meter and check for impedance
problem? I was reading that I should attach a silver mica capacitor
across the wires. Haven't tried this yet as they are still in the mail.
You should not need *anything* to match a 1/4 wave vertical. I know I
never have, on any band, or with any ground condition. If it doesn't
tune at least under 2:1 SWR, something is wrong... Like running two
verticals an inch apart...
You also shouldn't need any fancy analysers...I've never owned one
myself, and I don't have any trouble.
I was thinking ahead too when I put this stinker up. I've got a 22-turn
base coil sitting there as my next try but that sort of defeats my
original simplicity plan.
You shouldn't need it. Just curious...If this is going to be a
portable antenna, what are you going to do about radials? Are you
going to add ground radials at each location? What a pain....
For a portable 15 m vertical, I would use something like a base fed
half wave.
Can be mounted anywhere, no radials are needed. Can be elevated, or
near the ground, although the higher the better. But, you can get what
you have to work, if you ditch the 20m wire that is next to the 15 in
the PVC. Or at the least, ditch it until you get the other band tuned.
In the real world, if you tried to make such a dual band antenna, it
would be best to tune 20 first, and then 15. But I don't really
recommend you doing that as it's a PIA to tune. I'm almost sure thats
most of the trouble you are having. The PVC could be effecting the
overall length also. MK
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