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Old April 10th 04, 04:09 PM
Mike Coslo
 
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Bob wrote:
Hi
We have put together a dipole, each leg is 66 feet. We put a 1:1 balun and
it is running about 60 feet of 50 ohm coax. Presently it is about half way
up the tower it is intended for so we could check the SWR before getting it
up to the highest point. Presently each leg has some lags and dips, no major
bends but it is just hanging there, over some bushes and the entire thing is
over top of the house, and not touching anything but is very close to some
steel guy wires (uninsulated).
Now we can only tune this down to a useable SWR on the 80m band. On all
other bands we cannot tune it down to a safe operating range. We are using a
good antenna tuner but cannot get anything useable except for 80m. Here we
are able to tune the SWR right down.

Questions???
Would we be better without that balun?

Is the fact that the dipole is still too low and close to the guy wires (
but not touching) our problem?


Bob, the antenna as you describe it is pretty much *for* 80 meters. If
you want to tune the thing on multiple bands, and I'm assuming that you
want it for the Ham frequencies, you will want to replace the coax and
balun with ladder line, and use a tuner to match the impedence with your
radio.

- Mike KB3EIA -

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Old April 10th 04, 04:20 PM
Bob
 
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Hi, Thank you for your response. I do not have ladder line and only have the
coax basically. Is it acceptable for good results to simply use the coax and
then split it out to each direction of the copper wire? And not use the 1:1
balun? I was hoping to simply get the dipole in the air and leave it and
simply tune it at the transmitter to acceptable SWR and go from there. Now I
only get good SWR on the 80meters because of the length it is cut at. I was
hoping also to use the dipole with the tuner on 10, 15, 20 and 40. Is this
possible? The tuner is good and I know I will lose the power to the tuner
but would still get to use the other bands when needed.
Any more advice is greatly appreciated.
thanks
Bob






"Mike Coslo" wrote in message
...


Bob wrote:
Hi
We have put together a dipole, each leg is 66 feet. We put a 1:1 balun

and
it is running about 60 feet of 50 ohm coax. Presently it is about half

way
up the tower it is intended for so we could check the SWR before getting

it
up to the highest point. Presently each leg has some lags and dips, no

major
bends but it is just hanging there, over some bushes and the entire

thing is
over top of the house, and not touching anything but is very close to

some
steel guy wires (uninsulated).
Now we can only tune this down to a useable SWR on the 80m band. On all
other bands we cannot tune it down to a safe operating range. We are

using a
good antenna tuner but cannot get anything useable except for 80m. Here

we
are able to tune the SWR right down.

Questions???
Would we be better without that balun?

Is the fact that the dipole is still too low and close to the guy wires

(
but not touching) our problem?


Bob, the antenna as you describe it is pretty much *for* 80 meters. If
you want to tune the thing on multiple bands, and I'm assuming that you
want it for the Ham frequencies, you will want to replace the coax and
balun with ladder line, and use a tuner to match the impedence with your
radio.

- Mike KB3EIA -



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Old April 10th 04, 06:07 PM
Cecil Moore
 
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Bob wrote:
Hi, Thank you for your response. I do not have ladder line and only have the
coax basically.


The coax *IS* the problem. If you don't like to climb, you are going to
have to replace the coax with something like 450 ohm ladder-line. 100
ft. of such ladder-line costs about $17.

One other possible solution is to install an autotuner at the antenna
feedpoint but that is a pain to do.
--
73, Cecil, W5DXP




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Old April 10th 04, 11:41 PM
Mike Coslo
 
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Cecil Moore wrote:

Bob wrote:

Hi, Thank you for your response. I do not have ladder line and only
have the
coax basically.



The coax *IS* the problem. If you don't like to climb, you are going to
have to replace the coax with something like 450 ohm ladder-line. 100
ft. of such ladder-line costs about $17.

One other possible solution is to install an autotuner at the antenna
feedpoint but that is a pain to do.


Fer sure! I love my ladder line, and it's foibles are worth putting up
with IMO.

- Mike KB3EIA -


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Old April 10th 04, 11:39 PM
Mike Coslo
 
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Bob wrote:
Hi, Thank you for your response. I do not have ladder line and only have the
coax basically. Is it acceptable for good results to simply use the coax and
then split it out to each direction of the copper wire? And not use the 1:1
balun? I was hoping to simply get the dipole in the air and leave it and
simply tune it at the transmitter to acceptable SWR and go from there. Now I
only get good SWR on the 80meters because of the length it is cut at. I was
hoping also to use the dipole with the tuner on 10, 15, 20 and 40. Is this
possible? The tuner is good and I know I will lose the power to the tuner
but would still get to use the other bands when needed.
Any more advice is greatly appreciated.
thanks
Bob


The 1:1 balun isn't effecting the match on the other bands. If you
remove it, there probably wouldn't be much difference at all.

You could maybe put traps on the antenna so that it will be able to
resonate on multiple bands.

Another option would be to make multiple dipoles for the other bands.
The impedance mismatch will make the signal tend to go down the dipole
that corresponds to the desired band. Think of that sort of dipole as a
fan so to speak. If you go this route, You'll want to trim the lowest
band first, then work your way up in frequency for the other parts of
the dipole.

But all of these options are a good deal more work than the ladder line
method. But if you won't or can't use ladder line due to your
circumstances, I'd try the fan dipole.

- Mike KB3EIA -





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