Gabil’s GRA-7350TC is a compact vertical antenna that is designed for portable operations. The antenna itself is relatively lightweight and consists of three componants: a 102 inch telescoping whip, an adjustable section with internal loading coil, and an additional coil for the 80 meter band. You can also add an option compact portable tripod to complete the set. I previously used the Gabil system last fall and was not terribly impressed by it’s performance. Either the antenna was being lackluster or the bands weren’t in my favor.
I decided to give the antenna another shot. I like how the GRC-7350tc is compact and my hope is that it will be a foundational element of my growing QRP kit. As I’ve been used to running the full 1/4 wave whip on 20 meters and above, I think my expectations have been set pretty high in how the Gabil is to perform. But I gave it another shot.
November 24, 2023, the day after Thanksgiving, is known as black Friday to the rest of the world, but being self employed, the boss (me) gave me the afternoon off. I used the time to give the Gabil another test and to activate one of our newer POTA entities: K-9806 Mountain-Bay State Trail.
Mountain Bay State Trail
The Mountain-Bay State Trail runs for 83 miles from the western terminus at Weston, Wisconsin eastward to Green Bay. As it’s name implies, it is to connect Rib Mountain in the center of the state to the Green Bay near Lake Michigan. This corridor is an old Chicago and Northwestern rail line, which makes for a easy and beautiful ride. I like to set up at a trailhead in Hatley, Wisconsin in the Marathon County Public Library’s Hatley branch parking lot. At this point the Mountain-Bay intersects with the Ice Age National Scenic Trail (POTA K-4238) for a twofer.
This is the third time I activated the trail, you can read about my initial activation of the park here.
It is getting chilly so I’ve switched to operating out of the vehicle. My preferred setup is to put the Yaesu FT-881 on the dashboard of the vehicle and sit in the passenger seat so I’m not encumbered by the steering wheel of the car. For an antenna I’ll be running the Gabil GRC-7350TC vertical. The library is closed today so I have a practically empty parking lot to work with. The antenna was set up about 15 feet away from the car on the edge of the parking lot. Instead of using the window screen ground, I used 8 16 foot ground radial wires. The manufacturer recommend 4 10 meter wires, but I’ve had better luck with more, shorter radials, so I put my proven radial bundles to work. First up, the 15 meter band.
Tuning the Gabil is a bit finicky. Moving the coil slider up and down, you can easily miss your mark, so it takes very small movements once you are in the ballpark to find the perfect spot. On the 15 meter band I was able to get the SWR down to about 1.44:1, which was good enough for me. I’m not one to fiddle until it’s perfect, so if it is in the neighborhood of good, I’m fine with that.
The solar forecast for that day called for active conditions, I believe there was a solar storm predicted for later in the weekend but Friday had good numbers with the SFI over 170 and the A of 8 and the K of 2. As I started out on 15 meters, the conditions were slow with a lot of fading, but things kind of settled out and I consistently received good signal reports. I had a good, long run on 15 meters, about 110 contacts. No DX but plenty of Canadien stations. Since the band was hot, I decided to move up to 10 meters.
With conditions like this, we need to spend more time seeking out contacts on 10 meters. I had a bit of concern with tuning the antenna as an 102 inch whip is close to a 1/4 wave on 10 meters, so I anticipated that I wouldn’t need to use much coil. And sure enough, I was hardly at the -1- setting on the laser engraved scale. I got the SWR to about 1.5:1. Nothing special, but good enough. Calling on 10 meters, I racked up 15 contacts in about a half hour. Not like the run on 15 meters, but still respectable.
Since I was doing well, I decided to give 12 meters a try. Futzing with the coil, I got a match and we soon rolling. I picked up 8 contacts in about 8 minutes, including two stations: VE1BQC and KR5EEE that I worked earlier in the day on 15 meters. I also got an interloper that waltzed through my frequency and let me know ‘contesting’ isn’t allowed on the WARC bands. Fortunately POTA isn’t a contest so I didn’t give him the time of day.
To finish things up, I dropped down to 40 meters. I had activated the Mountain-Bay trail two week prior and had a long 200 contact run on 20 meters, so I felt like this time I could skip that band and concentrate on some of the others. Getting a match on 40 meters was a little more difficult. It could be partly because the coil has a higher Q on that band, or maybe my shorter radials are to blame, but I could only get it to about 2:1. That’s a bit on the edge for my tastes, but 2:1 match is only an 11% power loss and as long as the radio doesn’t complain too much, I’ll go with it.
Let’s just say that the losses weren’t much of an issue as I had no problem, at 3:00 in the afternoon local time (21:00z) in attracting a crowd. I ran for 15 minutes and got 25 stations with mostly good signal reports. I was at about 7207 KHz, so by this time the international broadcasters were starting to filter in. Which was fine as the sun was getting low in the sky. So I packed it up.
All in all, I netted 157 contacts on the Mountain-Bay State Trail that afternoon. Not too bad of a haul on an antenna that I initially panned in my review. Using the Gabil GRC-7350TC again, I have have thoughts on its performance. First off, the antenna works better on the upper bands than the lower ones. I hit the time of day right with my 40 meter activation, later in the afternoon as the sun was starting to set. The broadcasters hadn’t totally overrun the band and being a holiday weekend, there were people looking for me. 15 meters and above, I can really see this antenna excelling.
Second, a good ground network reallly is key for this antenna. You are at a compromise with the lack of radiator, so a substantial radial pattern will really make a difference. A greater number of shorter radials will actually increase your gain on the upper bands than fewer, longer, radials will. This article by Rudy Severns, N6LF, explains why that is the case. I’m going to have to experiment using the window screen with this antenna. The Gabil tripod is non-conductive so jumper wires are necessary to get good continuity with ground mesh. But I will give it a shot and report my results.
I’m not ready to dismiss the Gabil antenna, but won’t quite throw my full-throated support to it. I think it fills a portable operation niche and will take it places where my 1/4 vertical and large metal tripod are too cumbersome to travel.
K-9806 Mountain Bay State Trail 15m contacts with GRC-7350tc antenna
K-9806 Mountain Bay State Trail 10m contacts with GRC-7350tc antenna
K-9806 Mountain Bay State Trail 40m contacts with GRC-7350tc antenna
If you go
Mountain Bay State Trail passes through the communities of Wausau, Weston, Hatley, Norrie, Eland, Bowler, Shawano, Bonduel, Pulaski, Anston, Howard, Green Bay. A State Trail Pass needed for bicycle and horseback riding
Hatley, WI Trailhead
Marathon County Public Library, Hatley Branch
435 Curtis Ave
Hatley, WI 54440
Open weekdays and Saturday, hours vary