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W0LC
03-01-2004, 04:36 PM
I have a 160 meter sloper on my tower that affects the SWR (resonance) of my dipole, also hanging from the same tower. Is there a way to minimize interaction?

The Sloper doesn't appear affected by the dipole however.

KA5S
03-01-2004, 05:03 PM
ANYTHING large enough that couples to an antenna will affect its impedance. Remember those charts showing guy wire lengths to avoid?

The fix here is to reduce the coupling, preferably by increasing the separation between the two antennas, or running them at right angles to each other. You might install a remote relay to open the 160 meter sloper when you're using the dipole.

Cortland

W0LC
03-01-2004, 09:03 PM
Cortland,

Yes, I remember the lengths, etc.

I have the two at 90 degrees of each other already. Unfortunately, with the sloper at the top of the tower, it will be hard to install a dow key there now that the tower is up. Odd thing is that the dipole doesn't seem to affect the sloper. Supposedly, with teh remote antenna switch, the sloper is suppose to be grounded out when not in use. I do run a separate feed line into the shack for the dipole though.

I suspect electrically separating the sloper from the tower (floating) may work, else ground out the far end when not in use, although the antenna switching unit is suppose to do that anyway.

W8JI
03-01-2004, 09:48 PM
</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (wc5rr @ Mar. 01 2004,14:03)</td></tr><tr><td id="QUOTE">Cortland,

Yes, I remember the lengths, etc.

I have the two at 90 degrees of each other already. #Unfortunately, with the sloper at the top of the tower, it will be hard to install a dow key there now that the tower #is up. #Odd thing is that the dipole doesn&#39;t seem to affect the sloper. #Supposedly, with teh remote antenna switch, the sloper is suppose to be grounded out when not in use. I do run a separate feed line into the shack for the dipole though.

I suspect electrically separating the sloper from the tower (floating) may work, else ground out the far end when not in use, although the antenna switching unit is suppose to do that anyway.[/QUOTE]<span id='postcolor'>
Most sloppers are Marconi designs that depend on the tower as a ground. As a consequence, they greatly interact with anything else on or near the tower or the slopper.

Some slopers are simple ground inpedendent dipoles, and they will interact much less with other antennas. They do NOT depend on the tower for a ground.

Unfortunately a sloper for 160 that is ground independent would be over 200 feet long, or have some big loading coils. That&#39;s why the most common types are 130 ft long and worked against the tower, or have a loading coil and are worked against the tower as a ground.

You also might need a balun on the dipole to make sure it is not coupled to the tower. You do have a balun of some type on the dipole? Or is it fed with balanced line?

73 Tom

W0LC
03-01-2004, 10:32 PM
It is fed with 450 ohm ladder line opposite side of tower, 90 degrees oriented, and the ladder line goes to a balun prior to coming into the house so coax can be run.

I suspect the sloper has to be isolated or floating from the tower when not in use and electrically connected when you desire to use it. That way it gets it&#39;s capacitive &quot;hat&quot; from teh yagi(s), and the ground from the tower.

Odd it isn&#39;t affected by the dipole. I assumed (it&#39;s been a long time) that both would affect the other.

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