Installing a Hy-Gain 18-HT Hy-Tower


Yup. the Hy-Gain 18-HT is back in production!

Mine arrived the first week of November (2001), brand new and improved with all stainless steel hardware. And when I say "hardware" I don't just mean the nuts and bolts. The base plate, and the major fittings like hinges and tower connectors are all stainless as well. In addition, the first section of the vertical radiator has been redesigned. This section of the radiator now incorporates an internal tubing member that replaces the large wooden dowel for added strength.


After you call Hy-Gain and order yours, take a stroll out into the back yard and look for a lot of real estate. This antenna needs radials, A LOT OF RADIALS!

From what I can tell, by reading a bunch of stuff about ground mounted verticals, I'll need about 40 feet in all directions around 18-HT for good operation.

My lot is about 100 feet square, so this shouldn't be a problem . . . if I could just get rid of the house.

I picked a spot with about 30 feet as the shortest clear space (not counting the 90-degree slice of acreage under the house. There will be room for big long 60-foot radials around about 50% of the footprint, and there will be room for 30 to 50 footers around 25% of the space. The last 25% is partly covered by my house and the patio.


Here is the story of the construction process so far.


November 9. Dig Dig Dig, and then Dig some more

When you start digging your hole, make the opening dimensions about 3-inches smaller than you want to end up with. Get a square bladed shovel and square up the side walls by standing on the top and shaving down into the hole. This works great, and will prevent cave-ins.

Don't forget the forms. Find some 1X4 boards and nail them together with inside measurements to match the hole size. Use a big knife to taper the sod at the top of the hole so the boards fit down into the sod about half-way. This will give a nice finished appearance so the XYL doesn't have a fit.


November 10. Pour and Pray

I was afraid that the base fixture would be too hard to insert after the concrete was poured. Boy, was I wrong! Without the leveling fixture the base would have sunk into the concrete never to be seen again!

They might be a bit hard to see in the photos, but the way I leveled the base was with a couple of line levels. I tied some very fine gauge steel wire through the three tower mounting lugs, and pulled them taut. Hanging the line levels on the three wires made leveling a snap.

Here's a tip: When you are installing your 18-HT, pound in the stakes for the leveling fixture BEFORE you dig the hole. When I started pounding mine in, the sides of the hole started to cave in! If you forget (or choose to ignore) this bit of advice, pound the stakes in AFTER the concrete is poured. The walls of the hole will be fine, and the vibration will help settle the concrete.

I had to haul the concrete to the hole with a wheelbarrow. If you don't want to smash up your forms, or collapse the side walls of the hole, lay a piece of plywood right next to the hole for the wheelbarrow to roll over. This also keeps the inevitable concrete dribbles contained for easier cleanup.

Nobody told me this big chunk of concrete was going to settle. When I checked the height of the base assembly legs the next day, they were almost one-inch farther away from the concrete than when I started! Mine ended up almost 7-inches above the surface.

The pre-mixed concrete came from the local garden supply store. I opted for the motorized, one yard-mini-mixer with powered dump and hydraulic controls. The rental cost is a few bucks extra, but would be a bargain at twice the price. The flat dump-it-yourself armstrong powered trailers are real back breakers. I was also forced to pay $15 for the "environmental cleanout fee". I guess all this hazardous material that was dug out of the ground must be watched very carefully when it is washed out and put back onto the ground. (Welcome to Washington State and hold onto your wallet).

Total cost for concrete: $122.01


November 13. Pounding Brass

The installation manual calls for 1/2-inch diameter, 8-foot long ground rods. The hardware store only had four, so I bought two 5/8-inch rods also. I was worried that the "Acorn" clamps wouldn't fit, since the package called them 1/2-inch clamps. It turns out that the 1/2-inch clamps will fit very well on 5/8 as well as 3/4 rods.

After huffing and puffing for about an hour as I pounded in these beasts, I discovered that the 1/2 rods are a bit easier to pound in. However, you must be very careful as you are swinging the hammer. When your arm gets tired, and your aim begins to deteriorate, it is possible to bend the rods with a poorly placed hit. The 5/8 rods are much more difficult to bend. I suggest going with the 5/8 rods. The cost is less than a buck more per rod, and it is well worth it!

Don't pound them in all the way until you've attached the #10 or larger ground wires. When the wires are connected, pound them into the turf so they disappear. If you don't, be prepared for major lawn mower repairs in the spring.

Total cost for the six ground rods and clamps: $61.53


November 15. Melting pennies might be cheaper

The first batch of radial wire.

I shopped around and found that buying a 1250 foot reel of #12 bare copper wire was my best bargain. The lowest price I could find on bare copper wire (regardless of gauge) was 7 cents per foot. The same store (Home Depot) sold the reel to me for $64, or just a little more than 5.1 cents per foot.

Yes, I know, 1250 feet is not enough wire, but at least its a good start!

I picked up another 550 feet of wire for the "per-foot" price of 7-cents.

Total cost for 1800 feet of radial wire: $110.70


November 17. In the air - On the air.

Remember what I said about the stainless steel hardware?

Good!

There is an interesting characteristic of stainless steel that most manufacturer's don't ever mention. Its galling.

Yup, "galling". Stainless steel has a tendency to gall.

It turns out that when two smooth stainless steel surfaces come together, and some pressure and a little bit of sliding force is applied, the two surfaces will actually weld together. Trust me, this will happen at the most inopportune time, and in the most inconvenient place, with the most difficult to replace part.

Since I have suffered through this phenomenon on previous projects, I was not about to let it happen to my brand new antenna. Every bolt that went together on the 18-HT had a drop of motor oil applied to the threads before I started the nut.

This little bit of insurance made everything go together slicker than snot on a doorknob.


Assembling the antenna is much easier if the three completed tower sections are attached to the base plate hinges. Support the now horizontal tower about 2/3 of the length on a chair, box or, in my case a five-gallon plastic bucket.


Pay attention now, this is probably the best tip yet. When the first two sections of the vertical radiator are being assembled, the manual says (with emphasis) to be sure to get the vertical radiator in perfect alignment with the tower. OK, how do you do this? With a ruler? A tape measure? A level? A straight edge? Nope. Been there, tried that.

Make an "X" of masking tape from the face of each tower side to the opposite tower leg at the base. Now, peer down the center of the vertical radiator to the base. Adjust the brackets and fiddle with the U-bolts until the "X" is in the center! If you're concerned that the vertical radiator is sagging a little, align the bolt connecting the first and second vertical radiator sections so it is horizontal. Looking down the tube, if the bolt is not in the center (up and down) compensate in your alignment for the difference.


Assembly and erection of the 18-HT was done by me and me alone. Don't worry about the erection part. If a overweight grey-haired 47 year old desk jockey like me can do it, anyone can. Walking the tower up from horizontal to vertical was scary, but not difficult. Just be sure the wind isn't blowing!

I was tired and creaky last night when the antenna was finally vertical, but I couldn't wait to see if it worked or not. I strung a scrap section of RG-8 out the shack window and hooked it up. Reception on all bands was much improved over my old Sommer vertical. I called CQ on 14.058 and got a quick reply from WL7CKX in Willow Alaska. A comparison test indicated the 18-HT was also transmitting better. This is without any radials at all! To say that I was pleased is an understatement.


November 20. Turf Wars.
or
"Big Daddy" Has Nothing to Fear!

I was just out in the back yard installing radials (again). So far I have about 50 of them installed. Total length of radial wire is around 2000 feet.

I read a few articles about ground radial installation methods and techniques. I also interrogated a few of the local Hams. The best method I ran across was to install your radials before the grass was planted or the sod was laid.

Yeah, right.

One fellow said to use an axe to cut the sod. Another said to try a large knife. One character advised just laying the wires on the grass and holding them down with fence staples

I tried the axe and pizza knife tricks with little success. I also took a few swings with a hatchet and a USMC surplus machete.

What I ended up doing turned out to be so easy, it is actually fun to lay ground radials under the grass! The first step is to contact your local neighborhood roofer and borrow his "spud".

Really - No Joke.

A "spud" is sort of like a regular garden hoe, but the head comes out straight, instead of at a 90-degree angle. Roofers use them to peel off old shingles.

Use your spud to cut a slit in the turf about three inches deep and as long as the yard will allow.

Then, just jam the radial wire into the slit with a dandelion digger. It really works great. The "spud" and weed killer technique is definitely pure science in action!


To electrically tie the radials together I am using a ground bus scavenged from a household electrical service panel. You can also buy these at your local hardware store for about 5-bucks. The one I found is an aluminum bar with about 23 holes drilled clear through, and a set screw at each hole for gripping the wire. I make two radials out of one long section of wire, so I get two radials for the price of one screw. One ground bar is good for 44 radials and one screw left over for connecting to the tower base.

If you want more radials (like I did) it is no problem to put more than one radial wire into each of the ground bar holes. Be sure to go out and check the tightness of the screws now and then. Loosen each one a bit and then snug it back down to break through any oxidation. Remember - corrosion is the enemy!


The general installation sequence for the radials goes like this:


SWR Wars

If you are measuring SWR as the radials are installed, don't be surprised to see the SWR going up as more radials are installed. This is normal. The characteristic impedance of a 1/4 wave vertical will decrease from about 50 ohms to about 43 ohms as you go from zero radials to 36 or so (depending on the length and arrangement). The increase in SWR is more than offset by efficiency and radiation angle improvements with more radials.

After I had planted 43 radials, the SWR had gone up to nearly 2:1 on 15 meters. The lowest point of resonance was right where it was supposed to be according to the published VSWR charts, but it was much higher than the 1.33:1 shown.

Just for chuckles, I compared the theoretical zero-radial 50 ohms impedance with a predicted impedance of about 41.5 with 43 radials. This alone will account for a significant chunk of actual SWR. Combine this with the "perfect" VSWR charts, and I could easily see that my actual SWR at 21.180 MHz was right in line with reality.

To get the point of lowest resonance closer to my favorite "middle of the band" operating spot of 21.035, I simply adjusted the length of the 15-meter stub. I found this can be done either by extending the top adjustment section, or by moving the bottom clamp up a bit. Voila! SWR now is lowest at 21.035 MHz.

Remember, the VSWR charts are printed by the antenna manufacturer. Just like any advertisement you see in a Ham magazine, there is a lot of reading between the lines necessary to interpret these performance claims.

The charts are obviously made to portray the best possible SWR, which happens to be with the antenna configured for the poorest actual performance (i.e. no radials).

Consider this bit of information from the book "Reflections", By M. Walter Maxwell, W2DU, Published by the American Radio Relay League, 1990 (no longer in print).

"A ground system having 100 properly installed radials has negligible loss resistance (ref. 20).Many a-m broadcast stations use 240 radials, while the FCC requires a minimum of 120. With such a ground system the terminal impedance of the average quarter-wave vertical is 36.5 + j 22 ohms, and approximately 32 ohms when shortened to resonance.

When fed with a 50-ohm line, the SWR at resonance will be close to 1.6, rising predictably on either side of resonance. But a 15- radial ground system will have approximately 16 ohms of ground-loss resistance with this antenna. If we remove a few radials at a time from the 100- radial dial system, the increasing ground resistance, added to the radiation resistance, increases the total line-terminating resistance. The terminating resistance comes closer and closer to 50 ohms, reducing the SWR.

When enough radials have been removed for the loss resistance to reach 18 ohms, the terminating resistance will be 50 ohms for a perfect one-to-one match! But while the SWR went down, so did the radiated power, because now the power is dividing between 32 ohms of radiation resistance and 18 ohms of ground resistance!

Ground systems having from two to four radials may have a loss resistance as high as 30 to 36 ohms, so now the resonant-frequency SWR will be around 1.4 or 1.5. But instead of rising from this value, as it should at frequencies away from resonance, the ground loss holds the off-resonant SWR to low values. The low SWR simply indicates that the line is well matched, but it offers no clue that approximately half the power is heating the ground".

Don't forget, my Heathkit Cantenna dummy load has a SWR very close to 1:1.

Even though the 18-HT is advertised as an 80-40-20-15-10 antenna, I found it to be resonant on the 12 meter band as well. Back in the old days when this antenna was designed, there were no WARC bands, so the 12 meter resonance is an added and un-advertised bonus! With a tuner it will also do an acceptable job on 17 and 30. I can hear them and they can hear me.


Mercifully, my 1800 feet of wire ran out after the 43rd radial, for an average length of about 42 feet per radial. 1800 feet is about 0.34 miles. I spent about an hour on each 2-radial section of wire. That translates to 73,800 seconds. Do a little math and this yields a quarter mile time of 56,760 seconds or 10,000 times slower than "Big Daddy" Don Garlits.


Oh, yes, the big white thing in the photograph is a 1-1/2-inch PVC conduit I used to get my RG-213 coax from the house to the antenna. Here are a few pointers:


December 2. Typhoon Torture Test.

Since I was taking a breather from radial installation, getting on the air seemed like a good idea. My first foray way down yonder on 80 meters netted me my first ever 80-meter QSO with the Sunshine State. Running about 120 watts I had a crystal clear QSO with a Ham in Florida, and received a 599+ signal report to boot!

So far - so good. On 40 meters I worked Cyprus for the first time, and had a very FB QSO with an OB in Jolly Old England. Not to mention Uruguay, Brasil, Japan, Western Samoa, Argentina, and The Ukraine.

I don't know about you, but for me, working these places on 40 meters was really a blast!


Speaking of BLASTS, the 18-HT has not even been up a month yet, and it has already survived a substantial windstorm. On Saturday, December 1(2001), we had a blow here in Pasco. Sustained winds were 60 mph, with gusts over 70. The antenna came through perfectly.

I was a little concerned, considering all the work I had just invested, so as the wind was doing its thing, I stepped outside to see what was happening. The antenna was solid as a rock. The main vertical radiator was bending over a bit, but much less than I would have guessed.

I was even on the air as the wind was blowing it's hardest. There was a lot of atmospheric noise, of course, but the 18-HT was working great. Motion induced SWR changes were much less pronounced than with my former vertical. The old antenna was much smaller in size, and total height was lower - even though it was mounted about 20 feet above the ground. The next morning there was not a trace of bending, twisting, looseness or any other bad stuff. I have no doubt that the quoted 75 mph wind survival figure is conservative.


December 24. How Low Can You Go?.

Just as advertised, the 18-HT is tuned for operation in the phone portion of the 75 meter band. Since I'm a little mic-shy, and prefer to pound brass instead of flap my gums, something had to be done about this!

This morning I installed the LC-160Q base loading coil to extend operation down to 80 meter CW. The big coil enables operation on 160 as well.

Scrounging through my junk box, I found a multi-position ceramic RF switch taken from a radio carcass. I also came up with some ceramic standoffs that are probably good for about a zillion volts. I don't think the standoffs were really necessary, but they look sorta cool! The selector switch is housed in a waterproof plastic duplex box intended for house wiring, but it seemed just right for this job. The knob is a bit much also, but again, looks do count.

The manual says to use a hank of rope to secure the bottom of the coil. I don't think nylon tie-wraps were invented back in the dark ages when Hy-Gain cooked up this antenna - - but, this is what you should use when installing your LC-160Q.

Since there was only one inductor tap clamp provided with the LC-160Q, I just soldered the taps at the appropriate spots. As you can see there are four switch selectable taps available. Only three are hooked up now. One for bypass, one for 80-meter CW and one for the middle of 160. I'll reserve the fourth tap and the removable tap clamp for future tweaking.

Low-down operation great! I just worked Seoul, South Korea and Sau Paulo, Brasil using the new coil. Brasil was easy, but South Korea took 500 watts for a 579 RST.


PS:

Did you notice that my grass is still green on Christmas Eve? Pasco is Washington's "Banana Belt".


December 30. Static? What Static?

As you probably have heard, vertical antennas are noisy. Some of noise comes from static that is generated by wind and dust particles sweeping by the antenna. Sometimes I demonstrate this bit of wizardry by shuffling my feet across the carpet before I give my XYL a shocking smooch.

While this phenomenon may spark your love life, it is literally hell on radios.

I've received several static shocks when switching coax connectors on windy days.

To drain away the static build up from my 18-HT, I installed an RF choke from the tower to ground. A local Ham Genius (NY7T) shared this tip with me, and also gave me an RF choke from his bottomless junk box. Jim, undoubtedly, has the world's largest junk box and a truly fabulous radio station.

I mounted the choke in a weatherproof box similar to the one I used for the loading coil selector switch. The conduit openings were plugged with 1/2-inch PVC plugs and sealed with silicone goop. The PVC plugs were drilled so wires from each side of the choke could get out of the box. One side connects directly to the tower (the part connected to the feedline center conductor) and the other side connects to ground via the radial ground bus.

The choke is selected such that the impedance is high (several K-Ohms) at the lowest RF frequency (1.8 MHz). Since the choke reads only about 20 ohms at DC, the static charge bleeds away, while it looks like an open circuit to RF.




January 10. The Lightning Bolt

Static is one thing, but lightning is another.

Yes, I know, lightning is just big static.

But big static (lightning) will certainly smoke my little Hammarlund plate choke in about a milisecond. The feedline and my treasured vintage radios would be vaporized shortly thereafter.

There is not much anyone can do to protect an antenna or a radio station from a big-time direct hit, but for those pesky little bolt-ettes, or a nearby strike, most of the energy can be directed to ground via a spark gap.

Again my junk box produced just what the doctor ordered. A mild steel strap, a bolt, a couple of nuts, and a lock washer. The strap is bolted to the grounded antenna base and bent up so an adjustable spark gap is created between ground and the vertical radiator.

I sharpened the end of the bolt so the maximum electrical potential can be developed over the smallest distance and cross sectional area. That is why lighting rods on buildings are made with sharp points on the ends. This will get the lightning induced arc started quickly, and (hopefully) shunt the bad electrical energy into the dirt. Notice that the bolt can easily be adjusted to achieve a small spark gap.

You may also notice that the pointed bolt forming the spark gap is connected to ground, and pointing at the sky (via the antenna). Believe it or not, lightning doesn't travel down from the sky, but comes up from the ground.



Total cost for project: including sales tax, aspirin, band-aids, and marriage counselor (but not including junk box goodies or exorbitant shipping costs): $1146.32