CHEAP AND EASY: The Mountain Topper II

The Mountain Topper II is the second antenna I designed specifically for operating from the summits of mountains. (PHOTO MT 1).

Its lightweight, completely self-supporting (no trees or guy lines required), works all bands, and sets up in two or three minutes.

When disassembled, (PHOTO MT 2) it is a small package about 20” long and 2.5” in diameter (depending on what you come up with for a carrying case).

When assembled, it is a 9-foot radiator consisting of a 3-foot mast, a loading coil, and a 6-foot telescoping “stinger.”
The antenna is supported by a tripod made from a music stand – the type used by kids in high school band. The antenna has one coil for 20 and 17 meters, a coil each for 40, 30 and 15 meters, and 10 meters is tuned without using a coil.
All antenna pieces are made from two different sizes of brass tubing which slide together to make a tight friction fit so that no tools are required for assembly. The pieces are simply pushed together.

Changing bands requires changing coils but that process is very, very simple because of the way the pieces fit together. Fine-tuning the antenna for SWR is done by adjusting the telescoping whip at the top of the antenna.

Radials are attached to the antenna using alligator clips. The tripod elevates the antenna to about 3-feet off the ground. This gets the radials just far enough off the ground that they act as resonant, elevated radials and provide a pretty efficient ground plane with only a small number.

My solution to radials is to cut four radials each for 40, 30, 20, 15 and 10. When I put the antenna up, if I intend to operate only one band, I put all four radials for that band on. If I intend to operate more than one band, I put two radials on for each band I intend to operate.

Performance seems to be excellent on the upper bands – 20 meters and higher. On 40 and 30 it is definitely a compromise antenna because it is short and because the radials are not as elevated in relation to the wavelength.

The antenna is composed of the following pieces: tripod (PHOTO MT 3), base mount and feed point (PHOTO MT 4), three-foot mast made of two 18-inch brass tubes (PHOTO MT 5), loading coils (PHOTO MT 6) and six-foot stinger (PHOTO MT 7). See Figure 1 for the layout (PHOTO MT 8).

The project started with a music stand that I picked up at the flea market for 50 cents. I knew I could turn that baby into an antenna.

Shortly after that, I discovered a rack of 3-foot brass tubes in a variety of small sizes at the local hardware store. Amazingly, each of the different sizes telescoped very snugly into the sizes above and below it (amazing because it’s indeed seldom that things go right at the hardware store for the antenna homebrewer). I’ve seen this tubing at a couple of small hardware stores since then, so I think if you check a few stores you can find it. I found it at a local Ace hardware and a local True Value.

It is made by K&S engineering and the rack will say so. The tubes are 3-feet long and vary in diameter from about one-eighth inch to a half inch. I’ve found a place on-line that sells something similar, but you have to buy it in packs of five tubes.

I got three tubes. Two of them were 5/16” and two were 11/32.” These sizes telescope perfectly. The idea is that all parts of the antenna (base, mast, coil and stinger) have an 11/32” top and a 5/16” bottom and can all be simply pushed together when it is time to build the antenna. No screws – no nothing – to fasten together.

Once you find the music stand and the brass rods, the rest is easy. Here’s the parts needed (and estimated costs to buy new):

* 2 - 5/16” K&S engineering brass tubes ( $8)
* 1 - 11/32” K&S engineering brass tube ($4)
* 1 – 1” hardwood dowel (2 or 3 foot) ($4)
* 1 – 6-foot Radio Shack telescoping antenna ($5)
* Bunch of No. 14 building wire – depends on how many loading coils you want to build ($5)
* 12 – 1.25” X No. 6 machine screws with 2 nuts ($1.20)
* 2 – half-inch X No. 6 machine screws with 1 nut (.20)
* 2 – 2” X No. 6 machines screws with nuts (.20)
* Stuff for radials (see description below)
* 6 to 10 feet of coax with a BNC on one end. I used the mini coax to make it more compact. Yes, I know it has got a lot of loss, but not much in only 6 feet!
* Used music stand ($ - who knows?)
** TOTAL COST: $27.60

Here's the tools needed:

* Drill (I used a drill press but I THINK I could have done it with a hand drill. There’s a possibility the antenna would have looked a little crooked when assembled, though)
* Tap for No. 6 screws (probably $10 if you don’t have one) (PHOTO MT 9)
* Drill bits (5/16”, 11/32” and 7/64” – the 7/64” is used for drilling the hole for the tap for the No. 6 screw. Work with your hardware store to make sure this is the right size)
* Screw Drivers and Pliers
* Propane torch (optional - about $15 if you need to buy one)
* Tubing cutter ($5 if you need to buy one) (PHOTO MT 10)
* Some kind of saw for the dowel

Heres the instructions to build this thing:

First, build the three-foot mast. It is made of two 18-inch telescoping pieces (PHOTO MT 11)

* Cut one of the larger (11/32”) tubes in to 2 – 18” pieces
* Cut 2 – 4” pieces from the smaller (5/16” tubes)
* The 18” pieces will probably need to be reamed out on the end that was cut so that the smaller tubes will slide in to the end. If this is necessary, the tubing cutter usually will have a reaming tool built into the cutter (PHOTO MT 12). It is simply a triangular shaped piece of metal designed to scrape the inside of the tube to enlarge it.
* Now fasten one of the smaller 4” tubes inside the larger tubes at a depth of about 2”. I did this by soldering the small tube into the large with the propane torch. This is done just like a plumber “sweating” a fitting on to copper pipe. Put a little soldering paste on the little tube before sliding it in. Then, heat the larger tube with the torch and after it has had a good chance to warm up touch some solder to the joint. If all goes well, the solder will melt and be sucked right into the seam. Another way that is just as good as soldering is to drill a hole through the tubes for a No. 6 machine screw and fasten them together with half-inch X No. 6 screw. If you elect this method, add 2 screws and nuts per coil to the parts list.
* Slide the two 18” pieces together to make the three-foot mast.
* Build one or more coils (PHOTO MT 13). A coil is made of a 4.5” piece of dowel with a piece of 11/32” tube attached to one end and a piece of 5/16” tube attached to the other end. Screws that are 1.25-inches long are run through the dowel and into the brass pieces. Wire is coiled around the dowel and attached to the screws to form the electrical part of the loading coil.
* Cut one or more 4.5” pieces from the 1” dowel, one for each coil
* Drill a 5/16” hole in one end of the dowel about 2” deep, make sure it’s as straight as you can make it. I used a drill press and eye-balled it and was able to get these holes pretty straight. I think you can use a hand drill, but it’s possible the antenna will look a little off kilter when it’s assembled.
* Drill a 11/32” hole in the other end of the down about 2” deep
* Cut a 4” piece from the 11/32” tube and a 4” piece from the 5/16” tube. Ream out the 11/32” tube so that it will accept a smaller tube in the end.
* Stick the two 4” pieces into the ends of the dowel
* Drill a 7/64” hole through the dowel and the brass rod at each end
* Use the No. 6 tap and put threads in the just drilled holes. If you’ve never done this, it’s very simple – just screw the tap into the hole and it will cut threads as it goes.
* Screw a 1.25” machine screw through each hole and put two nuts on the end. Don’t tighten the nuts too hard on the screw. I had one coil actually lose the connection to the brass rod after I had screwed it too tight. After that experience, I’ve always been scared that one of my coils would suddenly lose electrical connection with the brass tube – but it has never happened. Nonetheless, I’d be more comfortable with a better way of making this connection. In the meantime, this method has not yet failed me.
* Coil No. 14 wire on the dowel as per the following chart for different coils (I’ve made coils for 30 and 40 also, but ended up using very light (No. 22) wire and am not terribly happy with them. If I had used No. 14 wire I would have needed longer coil forms (dowels) and I’m afraid the weight would be too much for the antenna. I plan to experiment more with this and hopefully I’ll add more coil data later) You may want to add one turn. If the coil is slightly too large, it’s easy to tune the antenna by shortening the whip. Experimentation is the best way to find what you like:

10 Meters – No coil needed
15 Meters – 6 turns
20 Meters – 25 turns
17 Meters – 25 turns

* Tie the wire ends to the bolts on the coil form.
* Wait until after you have tuned the antenna to wrap the coils with electrical tape. The tape will hold the coils securely in place but you may need to adjust the coils during tuning so it’s best not to wrap them with tape yet!
* Push the coil into the three-foot mast (PHOTO MT 15)
* Build the six-foot stinger. (PHOTO MT 16). The telescoping mast needs a piece of 5/16” tubing attached (PHOTO MT 17) so that it will slide into the top of the coil.
* Cut a 4” piece from the 5/16” brass tube
* Drill a 7/64” hole down the brass tube and the tap the hole to create threads for a No. 6 bolt
* The telescoping mast will have a hole slightly smaller than 7/64” in the end (PHOTO MT 18). Drill that hole out to 7/64” and tap it to create threads.
* Now you should be able to thread a No. 6 screw through the tube and into the threaded hole in the telescoping mast
* Push the stinger into the top of the loading coil.
* Build the base (PHOTO MT 20). The base is constructed to accept the 5/16” tube from the 3-foot mast on the upper side. The lower end of the base will depend on your tripod (music stand). I put another piece of 5/16” tubing on the bottom of the base and it slid into the tripod. The base also has two bolts that are used to attach the feedline and radials (PHOTO MT 21).
* Cut a 4” piece from the 11/32” tube and ream it out so it will accept a 5/16” tube
* Cut a 6” piece from the 1” dowel
* Drill an 11/32” hole about 2” deep into the 6” dowel piece
* Push the 4” brass tube into the just-drilled hole
* Figure out how you will mount the base to the tripod. I inserted another piece of 5/16” tubing into the bottom of the base and this was a perfect size to slip into the telescoping portion of the music stand. You might want to just drill the hole the appropriate size for sliding over the top of the music stand.
* Drill a 7/64” hole about 1” from the end of the dowel that contains the brass tube so that it goes through the brass tube.
* Drill another 7/64” hole far enough from the other end so that it DOESN’T go through the hole you drilled for the tripod to slip into. You don’t want the bolt that goes in this hole to make electrical contact with the tripod.
* Tap both of the 7/64” holes for a No. 6 bolt and insert the bolts
* Attach the middle of your coax to the upper bolt and the shield to the lower bolt. I arranged the lower bolt so it would stick out a little on both sides (PHOTO MT 23). This makes it easier to attach radials.
* Securely tape the coax to the dowel with electrical tape. This acts as tension relief for the coax so the leads won’t break off.
* Slide the mast onto the base (PHOTO MT 24).
* Prepare the music stand tripod. I had to cut the top off of the tripod mast because it was bent. I also had to modify the tripod a little so that it spread out a little further than the standard music stand. This stuff will depend on the music stand you end up with.
* Mount the base to the tripod (PHOTO MT 25).
* Construct radials (PHOTO MT 26). I have cut 4 radials for each band I’m interested in. I use very lightweight (No. 22) solid wire that I happened to get a hot deal on at the flea market. I think you can buy the same wire cheap at the hardware store. It comes as 2 wire twisted pair, but is easy to untwist. I really like sold wire because it’s easy to roll up and holds in a coil – without having to wind it on something or having wire ties to hold it in place. I use small rubber grommets for insulators and attached a 3-foot piece of wire on the end of the radial. This helps keep the radial itself from touching the ground. This is pretty important in order to maintain a consistent SWR every time you put it up. If you’re on a mountain where you can’t drive a stake, just find a small rock and wrap the end of the wire around it to hold it in place. I attach two radials to one alligator clip. If I’m expecting to work just one band, I attach all four radials for that band. If I expect to work more then one band, I attach two radials for each band I'll be using.
* Attach the radials and you’re ready to tune the antenna.
* I found that the coils sizes listed above made the antenna resonant on 10/15/20 with the telescoping whip fully extended – which is very convenient. For 17 meters, I used the 20 meter coil and shortened the whip by 2’8”. For 10 meters, use no coil and shorten the whip by 6”. In the field, it’s easy to adjust the whip because each section is 12”. If you need to reduce by 6”, just push one section half way in.
* Since the whip can only be shortened, not lengthened, you may want to make the coils listed above 1 turn more than my recommendation. That way you have a better chance of the antenna being able to be tuned by shortening the whip.
* If you don't have an antenna analyzer and need some help tuning the antenna using your transceiver and an SWR meter, send me an e-mail at gdslagel@yahoo.com and I'll give you a description of how to do it.
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Gary Slagel, NØSXX, is an expert outdoorsman, QRPer and builder living in Conifer, CO.