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Reviews Categories | Antennas: HF: Vertical, Wire, Loop | GAP Antenna Products Mono Gap Help

Reviews Summary for GAP Antenna Products Mono Gap
Reviews: 14 Average rating: 4.7/5 MSRP: $119.95 - 229.95
Description: A Mono GAP is a single band antenna that acts as an asymmetrically fed vertical dipole. Each Mono Gap is rated to handle the legal power limit and provide continuous coverage under 2:1 across the entire specified band.
Product is in production.
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WB0FDJ Rating: 5/5 Mar 18, 2017 13:59 Send this review to a friend
Solid antenna  Time owned: 0 to 3 months
I bought my first Gap in 1993 and have had excellent results from them. My second Gap (Challenger) purchased 6 years ago just went down when a tornado hit our town a couple of weeks ago and a guy rope failed. I decided to replace it with a 40 meter monoGap. I've reverted to my novice days and spend a lot of time on 40. And the 40 meter monoGap is basically a Challenger without all the extra "stuff" hanging off of it.

Assembly of the monoGap is, IMHO, much easier than the Challenger. You basically join the sections, place two tubes that hang parallel to the main antenna and solder the coax connector. Gap even includes the counterpoise wires all soldered to a common lug for easy placement. What I really noticed is that this antenna is lighter in weight and was much easier to stand and drop into the ground mount (which I already had in place) than the old Challenger. The absence of extraneous tuning tubes seems to greatly decrease the wind resistance and weight. If you know anything about these antennas you basically know that, once put together, they just "work". No need for tuning.

The SWR across the entire 40 meter band is 1.3 to 1. I'd say it is functioning as well as the previous antenna did on 40. For fun I checked some SWR's on other bands (which, yes, I know, doesn't directly relate to efficiency). 30M 3:1 20M less than 2:1. 15M less than 2.5:1. 10M about 3:1. The autotuner in my Jupiter easily matched these, we'll see how it radiates on those bands down the road.

My decision to buy this was based on the particulars of my real estate: very small lot, power lines on three sides. No way to put down a radial field that, say, a trap vertical would require. I have a back up antenna for 30-10 which has proven effective. I wanted something "decent" for 40. I made a lot of QRP 40 meter contacts on the Challenger, going down to the 500 milliwatt level and it looks like this antenna will do that too. My personal experience with customer service has been very good.

K3KO Rating: 3/5 Jul 28, 2016 11:58 Send this review to a friend
Works some  Time owned: 0 to 3 months
Purchased a GAP 17M monoband antenna after doing antenna modeling comparing a vertical dipole to my present antenna on 17M. Present antenna is a Vee with apex at 24' and ends at about 12'. Calculations indicated perhaps some improvement at lower angles.

Placed an order with HRO. It took more than a month to arrive! Not desirable.

Bottom line: Haven't found a clear advantage yet for the GAP. In fact, it seems to be down an average of 3 dB for stations at least one hop away.

On the other hand, it does work. If one didn't have some kind of reference antenna to compare to, one would conclude "it works".

It went together in about an hour and a half. One complaint. The self-tapping hex head screws kept slipping in the ratchet wrench. The screw shoulders were not square but somewhat rounded. Not something I've experienced before with other self tapping hex head screws. If you didn't keep the socket exactly square, it would slip.

Put it in the back yard with the insulating mounting pipe in a plastic bucket full of rocks-- clear from other large vertical metal objects. The counterpoises were about 6" above ground.

SWR was almost too good. 1:1 across the small 17M band. Such a good match makes me suspicious that there are significant antenna or ground losses. Have no way to confirm that.

Based upon the A/B comparisons done to date from our QTH in FL, it seems to have no clear advantage over the reference antenna. Admittedly, the band is mostly closed and the data set is only about 50 comparisons. A/B comparisons were obtained from a panadapter with a calibrated vertical scale.

US stations were almost all well below the reference antenna--not unexpected. DX stations (predominantly EU and some SA) show an average 3db loss relative to the present antenna. Unfortunately the really low angle long haul DX stations were not present in the data. The GAP might be superior for them.

Sometimes the GAP antenna shows a brief peak above the reference.

Other observations in our crowded neighborhood.
1) Noise floor is lower with the GAP. I expected the opposite. It seems to discriminate against many of the spurious signals from neighborhood electronic devices.
2)QSB is rapid and much deeper relative to the reference antenna.

The antenna is clearly almost 100% vertically polarized (well duh what did one expect). Test with a local who had both vertical and horizontal antennas showed a 30 db cross polarization effect. That is with him receiving on a horizontal antenna signals were 30db less than him receiving on a vertical. This initial antenna signal polarization gets lost after one hop so it is a non-issue.

Given these results, I'm tempted to try a 40M monobander. My 40M VEE is low and can't be raised. The GAP worked well enough on 17M to give some hope. Back to the antenna modeling program to evaluate that first.
KC9CZJ Rating: 5/5 Nov 8, 2015 14:53 Send this review to a friend
Another great mono-gap  Time owned: 0 to 3 months
Purchased a 40 meter model to replace my 20 meter mon gap. Was very happy with the 20 meter version... just wanted to have access to 40 meters. Assembled easily. Painted flat olive drab, and it hides nicely among my taller trees. So far, I've had contacts from Peoria, IL on 40 meters (London, Ontario Canada) and 15 meters (Cuba) with good reports. Haven't tried other frequencies because the antenna is not resonant outside 40 and 15. SWR is 1.5 across the entire 40 meter band. It's a little less than 3.0 on 15. The antenna slipped into the 20 meter mono gap's ground mount with no problem. Hid the radials in the grass with lawn staples. Highly recommended.
N4LSP Rating: 5/5 Mar 12, 2015 18:12 Send this review to a friend
New 60 meter Mono Gap  Time owned: 6 to 12 months
Last summer i purchased a 60 meter Mono Gap antenna.The reason for the purchase was to test a Mono Gap against a dipole on the 60 meter band.

I had hoped for many months that they would in fact build a 60 meter version and when they finally did i was truly excited about trying one.

The antenna arrived via UPS in the usual heavy duty Gap Antenna Products box very well packed.Upon finding no missing parts and no damage i laid all the parts out on my garage floor and began to assemble the antenna.

Now comes the only negative ive found about owning this antenna...In a word the assembly instructions are horrible.By far the worst ive ever seen in nearly 33 years of building antennas.The drawing provided looks as if it was drawn by a middle school-er.I was better off looking at pictures of antennas on their web site to sort out any confusion.

In the end i guess its a small thing to overlook when you consider just how well this antenna is made..But come on guys..

Anyway..The reason again for my purchase was to compare the Mono Gap to a dipole on what has become my favorite band 60 meters.

The dipole and Gap are both fed into an Elecraft K3 via 200 feet each of RG8X.The dipole is at 45 feet above ground and the ends of the dipole are running north and south with the southern end pointing at the Gap which is about 200 feet away in an open field.The dipole was adjusted for its resonance centered on about 5.350 giving it full coverage of the band with a VSWR below 1.2 to 1.

The Gap on the other hand was found to be centered well below the band.A call to Gap resulted in the recommendation of adjusting its counterpoise by shortening it 6 inches at a time.Two adjustments later the antenna showed centered right at 5.350 covering the whole band with essentially flat VSWR.

When the VSWR on the Gap showed flat i was somewhat concerned because all of my prior experiences with verticals have shown a good match generally means you have significant losses in the system.But the Gap is a vertical dipole and it should have a reasonably good match with low losses..or at least that is what i kept telling myself.

The on the air testing consisted of basic A/B testing using the antenna switch built into the K3 making for very quick switching.
My goal was to see what if any benefit the Gap would offer as compared to my dipole.I consider antennas to be like tools and you never know which one will work in a given situation and in this case i was more than curious.

The results are more than i had hoped for.The Gap has the unusual characteristic of being VERY quiet.Meaning as compared to the dipole the Gap is on average between 2 to as many as 4 S units quieter than the dipole in similar band conditions.That is not to say its weaker..but quieter.
A good example is while listening to WWVH the Gap was 4 S units quieter than the dipole while the signal was 2 S units stronger than the dipole.But the signal from WWVH the on the dipole was mostly in the noise.WWVH is at times not even copyable on the dipole while well above the noise on the Gap making easy copy possible.

Two other examples are the HF aviation weather broadcasts a 5.505 and 5.405 which are in western Europe.
The Gap clearly is quieter and many times several S units stronger on reception.There were times the dipole was as strong as the Gap but was always the more noisy of the two.The dipole was never stronger than the Gap on any stations over 2500 miles.

East coast stations were always stronger by several S units on the dipole but again the noise floor was always higher.At times i found myself using the Gap as a receive antenna for stations in the middle of the country because the dipole was more noisy in some cases making the contact possible.

The transmit signal reports generally followed the receive.I almost always received better reports on the Gap with the dipole sometimes being equal to but never better than the Gap in the EU.

Close in stateside contacts always reported the dipole being better than the Gap unless they were on the west coast where the Gap generally came out on top.

In closing ive found the 60 meter Mono Gap did what i had purchased it for which was to give me a lower angle antenna without the mess of tons of radials associated with a conventional vertical.
It also comes with their advertized and proven benefit of being a very electrically quiet antenna that at times has proven invaluable in pursuing DX on 60 meters.

I say the quality of its construction and its on the air performance is well worth the purchase price.So if you want a well built quiet vertical that doesn't come with the hassle of needing hundreds of feet of copper for it to work then try a Mono Gap.

Mike Baker
KI4VH Rating: 5/5 Jun 25, 2014 17:47 Send this review to a friend
A great antenna!  Time owned: more than 12 months
There is no arguing that a vertical antenna is a compromise but for those of us with limited space, funds, HOA restrictions, etc. it can be a very productive and efficient alternative nonetheless. For a number of years I have been interested in the GAP vertical design which utilizes a modified vertical dipole theory. Their multi-band versions have put me off because they seem “too busy.” Their assembly and maintenance look a bit much for me to handle. I’m sure they are all fine antennas as many amateurs have attested to on eham. But when I ran across the mono-band GAP a few years ago I was motivated to try one. I purchased the 20 meter version and had it ground mounted and on the air in less than two hours. The quality of the antenna is very good and the design almost flawless. It was very easy to ground mount using the provided drop mount and thanks to Georgia’s red clay it remains stable enough at my QTH without requiring a cement base to hold it in place. Wind resistance is 55mph free standing. The 20 meter version has three 11’ counterpoise wires which can be placed on top of the ground and can easily be removed when yard work has to be done in the area. The foot print is very small and standing at only 16 feet it is very inconspicuous. The antenna can be painted and hid amongst trees or bushes for HOA restricted neighborhoods. The performance is outstanding. The SWR is almost flat from the top to the bottom of 20 meters. No tuning is necessary, no traps to adjust, or radials to add. Just assemble by the directions and you’re good to go. So how good is the performance? I have worked numerous DX stations with it using my Oak Hills Research QRP Spirit at 5 watts CW. My longest contact was with a Russian station 6K miles away. That’s less than 1 watt per 1K miles! So if it can do that on QRP think about what it can do at the antenna’s 1500 watt PEP limit. It is very easy to break down for portable use it would be a great antenna for Field Day. If my Hustler 4BTV ever gives up the ghost I would be tempted to try the 40 or 30 meter version. This is a great antenna at a great price.

K4JC Rating: 5/5 Apr 11, 2014 10:59 Send this review to a friend
Simple and efficient!  Time owned: more than 12 months
Over the past year I have had the chance to try out the new 60 meter version of the MonoGAP antenna. Yes it is a big antenna at 43 feet tall, but is so light that two people can easily erect it. From start to finish the total construction time was about 30 minutes. Certainly an easy antenna to put together! It has a small footprint so it doesn't take up too much space (the counterpoise wires don't have to be perfectly straight.) I would, however, recommend guying this antenna if it will be used in a permanent installation.

The 60 meter band is unique in that, in the U.S., there are only 5 frequencies (or "channels", if you will) authorized for Amateur Radio, power output is limited to 100 watts ERP, and only USB, CW and a handful of narrow bandwidth digital modes are permitted. These restrictions notwithstanding, I found the MonoGAP to be an amazing performer. The first two evenings of operating on the band I made contacts with nine states and 5 countries outside the U.S. (Canada, England, Norway, Sweden and Denmark.) Many of the contacts told me I had the strongest signal on the band! Two contacts I received 5/9 signals from at 100 watts gave me 5/7 reports when I dropped the power to QRP levels (5 watts.) To me that is a testament to the efficiency of the MonoGAP. I have truly been able to work everyone I've heard with this antenna.

More and more countries around the world are beginning to authorize Amateur Radio operations on 60 meters, and many DXpeditions are including some 60m operation when it's permitted. It is a band with propagation characteristics very different from those found on 40 or 80 meters, and it has been touted as an excellent alternative to those bands for regional emergency communications. Because the MonoGAP is such a lightweight and easy antenna to install, I can see it easily becoming a staple of emcomm operations, as well as a great way for more DXpeditions to include 60 meters in their plans.

I have used many GAP antennas over the years and, while they have their limitations in harsh environments, I've found that when properly built and installed they do a fantastic job.
W7VI Rating: 4/5 Jan 18, 2012 19:20 Send this review to a friend
preforms great  Time owned: 6 to 12 months
This is my 3rd GAP. Two were great antennas; the wind took care of them at my last QTH; they bent in the middle( and I had them guyed. I aqain purchased one of GAP's; a new 30 meter Mono Gaps. I have had it about a year and it works great. What I do not like is the cable they use. I wish they would use something like the LMR family. If they did I believe it would be a 1st class design and a top quality antenna for the money. I have had to repair the cable twice due to weather not good. As an antenna they are great; but the cable needs improvement.
W7VI Rating: 5/5 Jan 18, 2012 18:44 Send this review to a friend
works great  Time owned: 6 to 12 months
I purchased a 30 meter mono gap about a year ago.
This was my 3rd GAP and they all did a great job.
The only thing I do not like is the cable they use. I do not like working with it and I really do not care for the quality of the cable compare to LMR 200. I wish GAP would change the cable they use. The antenna is great this 30 Meter Mono Gap works great but the cable has been repaired to due wx .
K4JC Rating: 5/5 Jul 21, 2011 19:05 Send this review to a friend
A real champ!  Time owned: 0 to 3 months
This year I had the opportunity to borrow a 40 meter Mono Gap to try out over Field Day weekend, and for a couple of weeks afterward. I expected it to work well on 40 meters, but was pleasantly surprised to find excellent performance on 20, 15, and part of 10 meters as well (with a tuner, of course!) Construction was very simple and, once assembled, was very easy to "break down" and move around for portable or Field Day use. In fact, setup for FD took all of 10 minutes! The included mount just taps into the ground, and 3 counterpoise wires are included so you don't need a whole field of radials. Signal reports were very good running only 100 watts. We ended up with over 700 Field Day contacts, and my own post-FD experience was just as good. Received signals were at least an S-unit stronger than on my Hustler 6BTV (which is to be expected comparing a full size antenna over a trap vertical) and I liked the fact that the antenna works on multiple bands. It's too bad I had to give the Mono Gap back; it could have easily found a home in my antenna farm!
N4NMK Rating: 5/5 Apr 25, 2011 12:03 Send this review to a friend
Great single band ant. Easy up.  Time owned: 0 to 3 months
While experiencing a mechanical connection failure (Unk at the time)to my 4-band verical, I was scanning eham looking for a antenna I could put up for the CG Net/Maritime Moble Net at 1200 est on saturday. Found the GAP 20M Mono ant. Ordered one right away and put up in an hour upon delivery. Last Saturday's Net I was receiving S5-S9 reports from the 4 corners of the US from my QTH in Southern DE. Antenna is ground mounted in my back yard. NCS thought I'd slipped in a small beam or wire on him due to my strong signal. Xcvr is IC-746PRO at 100W. As I usually only work 20M this is the antenna I'm sticking with.
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