Thanks to the installation of the Ameritron RCS-4 remote antenna switcher, it’s become much easier to compare my two HF antenna installations. With a flick of the rotator, it’s easy determine which antenna is the ‘loudest’ and which is tuning up to a lower final SWR.
The Antennas
G5RV
Mounted roughly 20′ in the air (trees don’t really get tall in Texas Hill Country), with a horizontal ‘L’ configuration, with 1 leg running N-S, and another ENE-SSW. This is fed entirely with repurposed RG6 satellite coax, through the remote switch box outside the house, and another 60′ run from the remote switcher to the ladder line.
Offset Fed Window 80 (OCF80)
Mounted roughly 20′ in the air, with an almost perfect N-S orientation, with the long let on the South side of the run. This fed with a mix of RG6 (shack to antenna switch), and 100′ of cheap RG58 from switcher to the feed elevated feed point in a tree.
RCS-4 Remote Coax Switcher
AMERITRON RCS-4 remote switch mounted and grounded outside shack/house.
Audible – which is the ‘loudest’
This was easy.. flipping back and forth between the G5RV and the OCF80 across various bands showed that the G5RV, was the loudest by roughly double (3db.. give or take). It’s quite obvious both to the ear, and to the scope which was the winner here.
Resonance – which is the most favorable
This is where it got interesting. Using the trusty RigExpert AA-35, I ran scans of both antennas from the shack side coax switch feed (through the switcher).
The results sort of conflicted with my observations regarding which antenna seemed to be working better. I downloaded the scans from the RE and superimposed the two on a chart showing the HAM HF bands:
This chart also explains why I’ve struggled with 80m as of late.. tuning is way off there. 60m is also a mess, but I’ve not tried to work 60 yet, so it’s not been an issue. But I’d like to see much better matching.
Considering that the RG6 most likely is a factor here in the shift and overall SWR, now that I’ve gotten hooked on HF, and gave upgraded radios, time to invest in proper coax. In the next week I’ll be ordering some, once I figure out how much I actually need! Another helpful feature in the RigExpert software is an analysis of the coax, including what I’m guessing is a pretty decent calculation of overall length. If this is right, I think a 500′ roll should get me from the office/shack to the switcher and out to the two antennas, retiring all the RG6.
