Thanks for all the great ideas given on this subject. I haven't had time to
reply individually to everyone yet.
I still haven't decided what the final configuration will be yet.
I was able to finishing installing the first set of guy lines on the higher
tower on Thursday before all the Thanksgiving festivities but Friday, Saturday
and Sunday it was too windy to work on the tower.
So I built the D40 Sunday, but was disappointed to see Cushcraft did not include
an element support with the D40 like they do with the D4 and 40-meter add-on
kits to the A3S and A4S. But I was able to build a support using lightweight
Phillystran and parts from my old antenna. Also, the measurements did not add
up. Adding all the measurements for each side of the element as shown on their
diagram then multiplying by 2 did not come out to the overall length given. And
there was an extra set of holes where the capacitance hat is installed which I
plugged with silicon, then taped. They were not drain holes as they were on the
sides.
Picture of the D40 at http://www.aa5au.com/antennas/rebuild/ant_d40a.jpg
73, Don AA5AU
-----Original Message-----
From: rtty-bounces@contesting.com [mailto:rtty-bounces@contesting.com] On Behalf
Of Don Hill AA5AU
Sent: Wednesday, November 23, 2005 7:00 PM
To: 'RTTY'
Subject: [RTTY] Novel idea?
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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