Lee:
I have a couple of suggestions for you to try. I'm assuming you are using
an antenna analyzer to check SWR. If you are using your rig's SWR meter, that
will change some fof the tests I suggest, but I'll let you know which ones.
You will also have to climb the tower a few times to conduct these tests.
1. Climb the tower and drop the 80M dipole. Then measure the SWR on the 40M
dipole. If it's different from before (better or worse), then you know you
have some kind of interaction between the two wire antennas.
2. If you see no difference in SWR on the 40M dipole, climb the tower again,
this time with a 1W 50 Ohm resistor connected to two small alligator clips.
Remove the coax from the Budwig connector and connect the 50 Ohm dummy load
across the coax. Go down the tower and measure the SWR with your analyzer
across the entire HF spectrum. You should see 50 Ohms plus a small amount of
reactance across most of the HF spectrum. Things might get flakey up at ten
meters. YOU CANNOT DO THIS TEST WITH YOUR RIG AND A 1W RESISTOR. If you see
50 Ohms with the above test, your coax is ok; if not, it's not.
3. You didn't say how close to the bracket you have the Budwig connector. If
it's tight up against the metallic bracket, you might try lowering it a bit on
a rope about two feet long. This will put a bit more distance between the
antenna feedpoint and the tower. Easy to do and doesn't co$t much.
4. If there is no interaction with the 80M wire and your coax tests ok, then
I believe your antenna is OK. You might want to put this antenna on the
opposite side of the tower, where the 80M dipole was, and string out the wires
flat, like the 80M set. This will raise the effective height of your (now
horizontal) dipole to 45 feet, a bit better than the average height of your Vee
- about 32.5 feet (average of 45 and 20 feet.)
With the 40M VEE at an average height of 32.5 feet, you have a high-angle
radiating antenna - an NVIS (Near Vertical Incidence Skywave) antenna. Your
signal will shoot almost straight up into the ionosphere and splash down to
earth within a few hundred miles around you. Your signals in that area will be
loud and clear. But DX won't even know you're around.
Bringing the ends of the wire up to more horizontal, and at a higher
elevation above earth, you will bring the main lobe of your dipole pattern down
a bit, shooting more signal off toward the horizon than directly skyward.
73 de
Gene Smar AD3F
-------------- Original message ----------------------
From: Lee Buller <k0wa@swbell.net>
> Ladies and Gents....
>
> Recently, I had to replace my 40 meter dipole (more of an Inverted-Vee)
> antenna because the coax center lead had broken off the. The dipole worked
> OK,
> but I was never really sure that I liked it. What is there not to like about
> a
> dipole antenna? (I sure I get some wise cracks here). The dipole did not
> seem
> to have a resonate point. It was below 1.8:1 on CW and was about 3:1 on SSB.
>
> So, the antenna was long.
>
> The new antenna, using a Budwig connector this time, shows the same
> characteristics. I cut the the antenna at 66 feet and I made sure that both
> sides of the antenna were the same length....33 feet. The antenna is mounted
> at
> 45 feet using a bracked that runs through the tower. The antenna in question
> is
> on the east side of the tower while an 80 meter antenna is on the west sime
> of
> the tower mounted on the same bracket. The feed points are about three feet
> apart....on seperate coax feeds.
>
> The end of the Inverted-Vee on 40 comes down to about 20 feet off the
> ground...while the 80 meter antenna ends about about 12 feet off the ground.
> The 80 meter antenna is in a straight line, while the 40 meter antenna has a
> slight VEE to to the tie points. So it has VEE to the the east....and a Vee
> down. This is hard to explain in words. I hope you experts get this.
>
> The new antenna was failry good on SSB but not great ... about 1.8. I
> attached two test leads to each end and the antenna show that it was at 1.8
> on
> CW...around 7.025. It seems that the test leeds were too long and now it is
> resonate below 7.0.
>
> But, there seems to be a crazy problem that I cannot get the anntenna any
> lower than 1.8 to one....thinking that there should be a length in there that
> should be "perfect." I cannot find the "perfect point" which I would like to
> have around 7050.
>
> Reading the Antenna Handbook...this antenna is working as stated although I
> did not anticpate the length of an inverted Vee to go longer. I've read the
> articles, but it seems there is something wrong with the antenna.
>
> Is there an interaction between the tower...the 80 meter antenna...the Vee
> to
> the east?
>
> Is the coax bad? IT has been up there for quite some time and it was used
> at
> another location before I put it up here.
>
> Comments, flames, postulations, editorials, and pontifications are all
> welcome. They might show on my web pate later on....so...you have been
> warned.
>
> Thanks for the discourse on a simple dipole
>
> Lee Buller - K0WA
>
>
> In our day and age it seems that Common Sense is in short supply. If you
> don't
> have any Common Sense - get some and use it. If you can't find any common
> sense, ask for help from somebody who has some common sense.
> _______________________________________________
>
>
>
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