For the past month or so, I had been considering making a couple of adjustments to my VHF-UHF antenna set up. Previously I had installed Diamond Yagis for satellite antennas and returned the 6 meter stressed moxon to the mast. But I at least needed to adjust some cables and get my one guy wire in place for winter winds. I had also been thinking about how I should set up my antennas for the ARRL January VHF contest.
Warm Day
Sunday hit the 70s here in Dallas. So I felt this would be the best time to make adjustments. Plus, based on some Saturday fun in the ARRL 10 meter contest my motivation was high to get set up for the January contest.
Mast Extension
So, I took everything down and added a mast extension to provide more stacking room for the 2 meter and 70 cm antennas, both mounted horizontally, ready for weak signal work.
The extension is a 1″ PVC pipe with a 1″ wooden down inserted in the center. The entire extension is then fitted into the 1.5″ fence pole I use as a mast on the rotator. That joint is clamped, with a PVC shim, and then bolted in place. You can see my handiwork in the photo.
Horizontal Mounting
Next the Diamond Yagis mount on the extension in the usual Christmas Tree fashion. You can see the full assembly in the photo.
That should give the antennas plenty of room, more than many rover setups. But I am getting a great deal of desense between 2 meters and 70 cm when I’m trying to work satellites in duplex mode.
Reinstall Duplexer
So I reinstalled the duplexer used as a desense filter for mode-J satellites, as recommended by AMSAT. I’d originally used this with my cheap yagis, also installed with horizontal polarization. I had found it wasn’t needed when I installed the side-by-side in vertical polarization. Wonder what interesting RF factor is at play there.
Next Steps
Well, there’s always next steps. I see my last antenna arrangement lasted six months. I wonder how I could get circularly polarized yagis on my push-up mast… We’ll also see how this all plays out in the January contest. Should be fun.
