Gabil GRA-7350TC antenna revisited. How much difference does counterpoise number and length make?
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- čas přidán 10. 09. 2024
- I've been using my Gabil GRA-7350TC antenna quite a bit lately, and while it's performed very well, I've been frustrated by how finicky it was to tune. I started playing with counterpoise length and number, and I think I've settled on what I think is the best compromise between performance, ease of tuning, and hassle. Thanks for watching!
My initial Gabil Antenna review: • My thoughts on the Gab...
Evan
K2EJT
www.buymeacoff...
With these small antennas ( WRC,Super antenna,and the gabil) I worked with various radial combinations. In the end I found that one(1) 33ft length laid in a circular pattern around the base of the vertical worked as well as 3 to 6 radials at various lengths. A single radial twnds to be directional. So I tried the circular pattern and have found that it works! N7KHH
Interesting! I'll have to give it a shot!
Heck! I would try that just because it sounds crazy and I like it! lol.
Hey & thanks... The first thing I'll do is make the recommended 8'2.5" (x4) counterpoise. I need to get out on the air, and life has me hopping. But there are a number of positive reviews & videos all with good signal reports...
I have only used 1 or 2 counterpoises, but elevated them to 4 ft, then got a good VSWR. Then I tried two 46"x 84" aluminum window screens overlapping each other by an inch, but choice to put in a 12 inch ground spike with integrated BNC connector I got from eBay. Suddenly my 7359TC tuned up nicely with full band coverage and 1.2 to 1 VSWR. It was like adding a 10dB amplifier for my 5 watts QRP signal. I intend to play with it some more, but am also experimenting with my MFJ 1979 17' telescoping vertical and also my PackTenna 9:1 UNUN where the feed point is within 12" of the ground and acts like my 16' counterpoise. I love experimenting & wished I could do it full time, lol. The beauty of the aluminum screen is it is quick to deploy and quick to stow, still looking for a small hollow tube to help wind them more tightly. Cheers, Davey - KU9L
Yeah, the window screen looks like a very interesting alternative. My only issue with it would be size if I was carrying the antenna into the woods. Close to the car though, and it looks like a good solution. After hearing how well it worked for you I'll definitely give it a shot! Thanks
@@EvanK2EJT it is super.light weight, the learning curve was to wind it up so it stayed as slender as possible, at 46" wide it could Bungie to my pack, but yeah, I invent reasons to haul more goods up the big hills, lol.
@@EvanK2EJT Evan, have you ever tried to use Faraday Fabric as the counterpoise? It's light, easily foldable, and may be a great alternative to the screen/chicken wire/hardware cloth as the counterpoint. I also like the idea of 12 inch ground spikes.
@@KD9ZHF I have. It doesn't work where I live. I suspect it's a ground conductivity issue. With Faraday cloth or window screen, I'm lucky to see a 2.5:1 SWR. It works in some places, just not here.
This antenna is now on my wish list. TNX for showing your counter poise experiment.
I work with AM radio stations antenna systems. The best you can do is to get as much metal at the base. It will be better to get more radials than longer radials. So 8 15' radials should do better than 4 33' radials. It easier to work with too
Yeah, I run 12 17' radials on my quarter wave vertical.
With a slightly longer radiator than the stock whip and three 15 foot radials, this is my “go to” antenna for POTA. Although, I will often use the stock configuration too when low weight and/or low profile is a priority.
I'll actually be running it for a POTA activation tomorrow. Thanks for watching!
Tuning for maximum cars :)
I have the Gabil tripod and been really disappointed with the quality of it - The two antenna inserts are great bit the tripod IMO sucks.
That's odd, because mine is awesome. I wonder if they changed the design?
Have you tried putting a common mode choke in your feedline to the antenna? I find it makes my MFJ "Big Stick" less susceptible to tuning changes if I touch the connector shell on the VNA.
I haven't, but I'll give it a shot!
Many thanks for the informative video. My 7350 was delivered two days ago. I'll take it out on a first run this afternoon. Have you been able to make many contacts working that the antenna?
Hundreds and hundreds. It works well for what it is.
Interesting video. When it comes to radials laying on the ground, the more wire the better.
My friend and I both use the PAC-12 vertical antenna. We both use three each 35 foot long radials and three each 17 foot long radials. This coming summer I am changing to 6 each 35 foot radials and not use the shorter radials.
Want better performance out of that antenna, add more radials. Your goal is not to hit a perfect 1 to 1 SWR. An efficient 1/4 wave vertical with a massive ground radial system will produce around a 38 ohm feed point impedance. If you show a perfect 50 ohm feed point impedance, you are showing an inefficient antenna.
Barry, KU3X
Yeah, on my WRC I run 12 17' counterpoises. I found on the Gabil it wouldn't tune no matter what I did with that setup, but on the 17' vertical it works great. I realize SWR isn't everything, but a lot of my radios are very sensitive to high SWR, especially my little QRP CW radios, so I need to be pretty careful with it. Thanks for watching!
I also have the 7350. I use 2-16' and 2-32' counters. It tunes 80-10 just fine.
Yeah, it's interesting how the counterpoises effect the tune. It tunes fine with the setup I have right now, but if I add a 32' counterpoise it tunes even better on 40, and while I haven't tried it yet, I suspect I'd need the long counterpoise for 80 as well. Thanks for watching!
DX Commander did a whole video on counterpoises. There is a point of diminishing returns. I wonder how much of that long coax comes into play with the SWR?
Good question. The coax is only 15' long, but I'm sure it still plays a part.
How long should the counterpoise be for all bands beI have already purchased this antenna and also tripod new ham here thanks in advance.
I just run those 4 counterpoises in the video on every band from 40 up. On 80M I use those 4 radials plus a piece of Faraday cloth.
Well first ya yalked me into the tripod, that was not hard. I was iffy on the antenna but ya sold me. Maybe you should be sellling cars not fixing them lol. Im a hard sell but this should pair well with The SW-3b (Next on my list) for when I care to hike in some place, or throw in my EDC bag to hop out and make a quick activation or whatever.