Amazing HF Antenna performance in a small package.
I spoke to Steve at Alpha antennas at length before deciding to get one of these fine units. First, I wish to tell the nay-sayers that this is not a simple Balun system, and it is not a cheat of some kind.
It is a special matching network that works to complete the antenna system using a properly grounded/bonded counterpoise. For mobile, this is the body of the vehicle, properly bonded to allow RF current to flow to balance the antenna currents derived by the tuning/matching system and the matching network. Think of it SORT of like an end-fed non-resonant wire antenna system but using a short vertical whip.
Transportable field tests: ICOM-718 running 75-90W, MFJ 200W tuner (939I), 35 feet LMR-240. Kitchen table, cable out to tripod setup 25 feet from house.
Before installation, I wanted to try this unit as a ground plane vertical. So, I also got the 4-foot Alpha tripod and adapter, plus the 13-foot military whip. I also have two long (12 and 17 foot) MFJ whips (Alpha offer a 17’ 9” telescopic whip), and a 102″ CB style whip, which I had planned to cut back during testing – more on this later.
I used 4 radials of 25 feet length, one to a ground rod. (west) The setup is in my backyard inside a wooden fenced area, no more than 25 feet from my house, with all sorts of “stuff” in the way – a tree 30 feet away, misc. sheds in neighbors’ yards, and homes in a usual suburban setting.
13-foot military tests: On receive, this system was AMAZING on all bands including SWL bands and down to around 700kHz, with lots of sensitivity and not much noise. I was very impressed. Routine contacts on 20/17, 15 during an opening and 10 during another opening. 40m was not as efficient, but still able to hear everyone on several nets, and minimum 56 reports throughout N America. All on 75-90W. Many times heard routinely above lightning crashes (40m) evenings in Midwest USA.
Best results were in late July, when I got some DX into Eurasia. 5×8 report from Azerbaijan station on 40m, and 57 on 20m into Finland, 58 into Canary Islands, and 56/57 on 20m into Estonia. 80 watts. Also had a brief QSO with a guy in the Falklands – much QSB, but best 20m signal on 80W with this setup was 55/56 from him. Not bad for a 13-foot vertical running 80W only 4 feet above ground in no clear area at all.
Unit with 10 lb. weight below tripod held up overnight on a 45 mph wind. Awesome camping setup FYI!
Similar results with 12 foot MFJ whip – all bands from 10-40 tunable easily, and similar results. 17 foot antenna was better for 40/20, but was not good for tuning the WARC bands. 15 also good. So I recommend going no higher than 15 feet with this as a stationary vertical antenna system unless you plan to use a wire length run more than 30 feet as a sloper, etc., instead of a vertical whip.
Short whip testing: Used a 102″ whip to begin with. Tuned okay on 40/20/15, but really bad on 17/12. 10 nearly perfect. While it worked okay, I found places where RF return currents would cause cut outs. So, the 102-inch whip was forcing RF into the coax shield more. Not good. Saw this on occasion using 17-foot MFJ whip on a handful of spots mainly on 20/40.
Cut whip to 95.5″ with total length including spring to be 98.5″, or 2.5m long. Noticed better tuning on WARC bands and bad spots on some regions of 10m (lower portions below 28.3). 20m Was decent, but had two “cut out” locations. 40m was fine. 15 was decent but not ideal (no less than 1.6:1 SWR in most areas.
So, I stopped and remembered my chat with Steve, and thought about a good compromise, of 2.25m total length (3/8 on 6m, 3/16 on 12, etc…) and close to 8 feet, and longer than 5 feet.
Last two days… WOW!!! Tunes all bands in the 40-10 region VERY well, Best on 40/20/15/10, but also very good (<1.4-1.5 SWR on whole band) on 12/17. Lower on 12m and upper on 17m best.
Sensitivity is nearly as good (MAYBE 1S unit down from the 13-foot whip on receive, and lower noise floor, by 1-2S often (may be conditions dependent).
7.5 foot (88.5″ total, 2.25m) whip is also exceptional. Under fair to good conditions, Was Able to hit Costa Rica 58, CONUS 56 to 59+, Italy 57 on 17m, Brazil and Chile at 56/57 on 20m, and Slovakia at 56 with heavy QSB on 17m! We’re at a low in the spot cycle and hit and miss into better fall conditions, and I am doing significant DX call-ins without much extra effort over my stationary setup with 250+W and a 60-foot sloper!
So, my setup will be using the cut down 102 whip to 2.25m with 1″ corona ball From Hi-Q (ask him to drill hole to 1/8″) and 25 feet of LMR-240. Binding critical regions of my 2013 Edge in progress.
I’ve had significant results with the setup and refinement that I sent at least a dozen folks to Steve at Alpha for this fine product offering. What I prefer with the Alpha Moto is a clean, sleek line look with simple whip(s) versus the rather beefy look of a Tarheel system. The Moto gets out, looks good and is multi-functional.
I can’t wait to finish this up for a road trial in an open area of the province! Stay tuned!
Darren
VE4VE (ex VE4DL)
More reviews on the HD-FMJ antenna
See the HD-FMJ antenna
View all Product Customer Reviews
Open the Alpha Antenna Home Page
