I can't see a problem..
except, maby the rotor cable on the upper rotor may get large doses of
RF while it passes between the A3S
a simple fix could be sheilded cable..
Tony
NN1D
Don Hill AA5AU wrote:
> This is not directly related to RTTY, but again, I trust the opinions of those
> on this reflector. A great bunch of ops here.
>
> I've not ever heard of anyone doing this before. But it seems to be an
> excellent solution for me. I was going to keep this secret, but I just can't.
> I need some input from others.
>
> I'm in the middle of rebuilding my main tower. Right now, it's at 46 feet
> waiting for me to install the first set of guys. Why the unusual height? Six
> feet of tower sticks out from the concrete base. What I have left is one more
> 10' midsection, then the 9' top section. The tower will be at 65' when
> finished.
>
> Anyway, for those following my rebuild may remember that I wanted to install a
> 40 meter beam. Well, I cheaped out on this idea. In order to get something
> up
> for Roundup, I've purchased a new A3S and D40 (D40 is a Cushcraft 40M dipole).
> You have to realize that my ground crew consists of my wife and the neighbor's
> German Shepard. So I have to stay lightweight right now.
>
> Prior to Katrina, my main antenna was an A3S with the 40 meter add-on. With
> the
> D40, the rotatable dipole will now be separate from the tribander and I can
> use
> both antennas at the same time with my SO2R setup.
>
> Here's the kicker. I will install the D40 above the A3S and want at least 10'
> of separation. In trying determine if I should align the D40 with the A3S or
> offset it 90 degrees in azimuth, I have come up with a radical idea of
> installing a separate rotor above the A3S. My main rotor is the M2 RC2800.
> It
> will sit inside the top section. I will then install a piece of 2" aluminum
> conduit (mast) from the rotator up through my thrust bearing, but only
> sticking
> out of the tower a couple of feet. I will install the A3S here. On top of
> the
> conduit mast sticking a couple feet from the top of the tower, I'll install
> what
> will probably be a Yaesu G-450A with the mast mount (haven't purchased yet)
> and
> then a 10' piece of 2" aluminum conduit. Near the top of the 10' piece of
> conduit, I'll install the 18 lb D40. I've compiled the figures and the M2 is
> more than enough to rotate everything and the G-450A will handle the D40 with
> no
> problem. What I like about the G-450A is that it can be set to stop at any
> direction and shows an LED for overlap which I can set at 90 degrees. Also,
> unlike the G-800S, you must push the left or right button to move it, so it
> won't rotate all the way around by itself. This is important because of the
> slack I'll need in the RF and rotor control cables from the D40 and G-450A.
> The
> overlap LED will alert me that the D40 is offset. Keep in mind that the D40
> will only need to be rotated up to 90 degrees offset from the A3S, never any
> more than that.
>
> I've been thinking about this for weeks. I can't think for any reason why it
> wouldn't work. I hope to simulate the entire setup on the ground, possibly
> this
> weekend using an old CDE mast mounted rotator I have. Other than the G-450A,
> I
> have all the other hardware already. Has anyone ever heard of this setup
> before, a rotor on top of a rotor?
>
> By the way, updates on the towers on my new antenna page at
> http://www.aa5au.com/antennas/antennas.html
>
> 73, Don AA5AU
>
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>
>
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