Assembly Of The Gap Challenger DX Antenna

IMG_7906The Gap Challenger DX vertical ground mounted ham radio antenna arrives via UPS in a rather unassuming flat box.  I say rather unassuming because the size of the box really doesn’t lead one to believe that the parts contained in the box would contain a 31.5 foot tall antenna.  When assembled and mounted in the ground mounted tilt base our next door neighbor came around the corner of their garage and exclaimed, “OH MY – Look at how BIG that THING IS!!!”.  I had to agree that, after it was assembled and mounted, it WAS quite a sight in our mid-city residential lot.

IMG_7909The HF ham radio antenna’s relatively good assembly manual warns the person ready to assemble the antenna to select an area where screws and lock washers will not be lost.  It wans that grass lawns are legendary screw and lock washer eaters with big appetites!  I selected our driveway along the side of our home in Appleton, Wisconsin as a good location to assemble the antenna in.  My wife, Jane (KD8KRS – pictured above) suggested we use at least one long folding table that she had in the basement.  I had not thought of use of the table and it turned out to be a very good idea!  The ham radio hf antenna assembly manual advises that assembly of the antenna takes about one hour.  My favorite quote from the hit TV show “M.A.S.H” by Colonel Potter is…  “HORSE HOCKEY!”.  We were prepared for a longer day.  Research on the internet on places like indicated that assembly times by average humans were more like three hours.  I was glad that I had read that before we started.  We knew what to expect.  With that said, if this antenna were to come crashing down and we needed to build a second one we probably could do it much faster knowing exactly how it goes together.  AB9NN’S BIG TIP – Get a good sized plastic container to keep all of the screws, washers, etc. in during the assembly process.  On a windy day put a brick or other weight into it so it won’t blow away.  This was a big help for us and we ended up not dropping a single screw.  OH!  The factory says they supply extra screws so expect to have some extra parts.

IMG_7913The antenna came complete with what I considered to be a project saving nut driver that was perfectly matched to the screws shown in the photo below.  I suppose there are better ones on the market but this one did a nice job.  I tried both a manual screwdriver and a motorized one.  Neither of these could get the screws started.

IMG_7917Note that the holes for the screws ARE pre-drilled.  The hf ham radio vertical antenna assembly manual advises that the holes are intentionally drilled smaller than the size of the screw and are NOT TAPPED.  This is done to ensure a good tight mechanical and electrical fit.  It works!  However, that means that it is a long day cranking these screws through the metal.  Getting them started is tough.  Lining them up vertically is important so they go in straight.  Once started they are still tough to crank in for about 80% of the way.  For the last 20% they go in quite easily.  That is how you know you are near the end of the threads and you should be prepared to stop cranking.  We did not strip or lose one screw – whew!

There are maybe 30 of these screws to put in.  It makes for a long day.  Now, I am an Auditor by trade.  I spend my day clicking my mouse and typing.  I found that my hands were quite red for about a day after doing this assembly job.  My shoulders and upper back were quite tired for the next day.  For me, it took quite an effort to get these screws in and tight.  If you work on these sorts of tasks all day at work then you probably are laughing right now and will find this quite easy.  If you are elderly then get someone to help you with this project.  I found that having Jane my wife helping me with this was very valuable!  Jane handled reading instructions and positioning of parts, holding items steady for me, etc..  You can do this assembly job alone but it was VERY nice to have a second person to help.

IMG_7901The instruction manual…  I would rate it as “B”.  It could be better.  I had read some complaints about it on the internet.  I did not find it to be THAT bad…  In one or two instances the printed illustrations perhaps could have been a bit more clear.  It very much helped to be able to see some close-up photos of assembled antennas on the internet.  This helped to determine at what angles some of the tuning rods should be positioned at.  On a windy day be VERY careful that the manual does not blow away.  If it DOES then you can find the on-line version at GAP’s website.

IMG_7932This photo will show you some of the parts of the antenna.  You can see quite a few screws that have to be installed along with some of the supplied jumpers.  Care must be taken with some of the smaller metal tubes that serve as the tuning rods for the antenna.  I could see a person bending or breaking them.  Some people on the internet wrote that they inserted wooden dowels to strengthen some of these tubes.  The factory indicated that this was NOT needed.  In their words, “That’s just some hams having to fiddle with something to try and make it better.  We’ve sold these for decades and they’ve survived Canadian winters just fine…”.  I WILL audit that statement by the way…  chuckle.

IMG_7923One issue, in my mind, is the exit / entry point of the coax cable supplied by GAP.  This is a short amount of coax by the way – maybe 2 – 3 feet.  A connector and your coax from your home connects to this coax.  You will need to supply a female – female adapter if you are going to terminate your coax with a PL-259 connector.  But I digress.  The issue here is that, on first blush, the coax sits on a somewhat sharp edge of metal of the hole of the antenna.  I wondered if this would cut through over time.  Now – if you are expert at such things you may want to consider adding a grommet here.  If you do not I doubt that it will cause a problem.  After the antenna is installed and connected there should be no movement in the cable so I doubt that it will be a problem.

IMG_7911That is me, AB9NN, working on tuning rods of the antenna.  One of the toughest parts of the antenna is a spade plug that installs at the top of the antenna.  I wish that I had gotten a picture of it but that is my failure.  Sorry.  What is tough about it is that it is hard to tell if a proper connection is made.  There are two connectors that must be pushed together.  The connectors are modular plastic and it’s kind of hard to tell for sure if you have them all the way in and tight.  After you connect them you have to tuck them into the top of the antenna.  If you get a hugely high SWR reading on the antenna during the initial test – check this connection!

IMG_7922Another part of the construction phase for the Gap Challenger DX hf vertical ground mounted ham radio antenna is having to fish the coax through the newly assembled antenna in such a fashion that it can be grabbed through a small hole seen in a photo above.  To do this the instruction manual advises you to bare the end of the coax and then kink it at a 90 degree angle (or better).  In actuality it didn’t take long to get this step accomplished.  But – when you are trying to position the coax in the pipe so the end can be grabbed at the other end through a hole in the side of the pipe it can seem like an eternity.  It’s a bit like pushing on a rope and is somewhat imprecise…  Hint – a needle nosed pliers may come in handy for this step.  I got it with my fingernails but was close to going for the pliers.

IMG_7935Once the antenna is assembled it is ready to be installed whatever mount you choose.  We used the GAP ground tilt mount.  That is the subject of a couple of separate blog posts on this blog.  If you look for them you will find them…

We finished construction of the Gap Challenger DX antenna late on a Sunday evening and so we elected to set it under a shelter next to our garage and wait for a calmish day when we had time to mount it, guy it, trim a nearby tree or two and install the PL-259 connector on the end of the coax.  Those stories to follow in future posts.

Knowing what we had to go through to assemble the antenna – would we do it again?  Yes.  So far.  I will report on efforts to test and use the antenna in future posts.

Stay Radio Active!

Jon Kreski – AB9NN – Appleton, Wisconsin / Green Bay, Wisconsin area

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