Disclaimer - This material is presented here to help others, who have never done this before, as was my situation. It is a collection of information which I obtained from many very helpful people. Please do not hold me responsible for problems that you encounter as a result of reading this information.
The Infernal Tower
By Rick Bandla (VE3CVG)
NOTE: An UPDATE follows the main information
I've had my licence since 1962 but until now have never had a tower. When I started this project in August 1999, I didn't know anything about towers, and I still don't know much but I've gathered a lot of information from people who collectively have a great deal of experience. All of these people were really helpful and generous with their time. I decided to record this information, tainted with my experiences, so that others will have a starting point. I hope you find it helpful and informative. It is a living document and will be added to as the story unfolds, so check back. Please let me know if you find the material useful.
I bought a used tower, so some of the information on this web site deals with the restoration and repair work associated with my tower. If you are starting with a new tower, you can adjust the information accordingly.
Preparing the Tower
Make sure that any loose paint and rust is wire brushed off your tower and that any rusty area is painted. I recommend a metal rust paint such as Tremclad. I used 3 litres 2 white and 1 grey (mix to your own preference) and had some left over. All the rivets must be secure or replaced with a tight fitting machine screw and lock washer.
When I first tackled this job, my ham scrounging showed through and I figured that I might use regular 1/2" bolts, washers and nuts and channel steel for legs and I probably could have but common sense prevailed and I bought the right stuff. Be sure to obtain the proper tower bolts for your tower. In the case of my Delhi 48 these are a very solid looking tapered shoulder bolt with an inside star washer for the hex nut side. Similarly, don't scrimp, buy the correct galvanized steel tower legs for your tower. The prices are unreasonable, but in the long run worth it.
For your information and frustration, the Delhi tower people, located near Delhi, Ontario, just east of London, recently sold their tower manufacturing plant to Taco Antenna and their phone number is 1 800 463-1607, but they only sell to dealers. You can phone them and get the dealer nearest you.
Inspect your tower carefully you want it to stay up there for at least 12 years! If any bolt holes are elongated, you must attach backing plates to reinforce your tower attachment at this point. In my situation, my section 7 to 6 joint (my sections number from the bottom starting at #8) was elongated slightly. I bought a piece of 1/8" steel strapping, 1" wide and 4 feet long and made 3 plates (one for each leg) and drilled them on a drill press carefully, with 4 holes. 2 aligned with the original holes, and 2 new holes above and below the joint. (Don't cut the pieces off until all holes are drilled - safer and easier on the drill press) I did not use a tapered shoulder bolt in these extra holes but I did use a straight shoulder bolt and lock washer.
Be sure that your mast bearing and rotator will mount with the proper size bolts. Everything must work smoothly by finger, because when you are at the top of the tower, you don't want to mess around with rough running threads. I mounted my bearing ahead of time and made sure that it was exactly in the centre.
I went to a local scrap dealer and bought a thick-walled, 2" aluminum 12' pipe for $2 per pound. It weighed about 10 pounds. What a bargain! It's slightly less than 2" diameter but close enough for the weight that I'm putting on it. The mast should extend down into the tower through a well-greased mast bearing, which can be adjusted to centre the pipe. The further down into the tower the mast goes, the less stress on the rotator, etc. I'm not sure what the ideal arrangement is, but mine is a 12' mast 6' above the tower and 6 feet down into the tower. It might be nice to have a mast all the way down to the base of the tower, but there are complications doing this, including consideration for the weight of the pipe downward onto the rotator, and also the need for intermediate mast bearings. This might also result in some backlash when rotating the antenna. Anyway, my mast extends 6' into the tower.
The Mast Bearing
I have a Delhi MMB bearing which was kindly provided with my tower. Gord (VE3KKL) explained to me how to remove the little plug in the side of the bearing. I ground off the metal burrs holding the plug, then carefully drilled a small hole in the middle of the plug. I screwed a tiny self-tap screw into that hole, and was able to use that as a handle to remove the plug. If you try this, be carefull not to lose any of the ball bearings. They are very loosely packed in there. I applied a grease nipple, mounted in a stainless clamp, over the ball bearing access hole, and lightly tightened this assembly into place. I charged my old grease gun with heavy duty grease and pumped as much grease as I could get into the bearing, while I kept rotating it a bit at a time. After I was sure that it was well-greased, I removed the clamp and grease nipple and put the original plug back over the hole. I kept this in place with a piece of black vinyl tape, held in place by a stainless steel hose clamp.
There are plenty of reasonably priced rotators available used on the swap shops. Mine was a Yaesu G400R with a very attractive display, and I only paid $75 for it. But when I bought it, I knew that I had to find a new mast clamp bracket for it. A new Yaesu bracket kit cost me $45, so for about $125 I ended up with a good reconditioned rotator with new bolts as well. Remember to find some rotator cable. This should be vinyl jacketed, and have enough conductors to work with your rotator. Be sure to use stranded wire of a gauge suitable for the distance from your shack to the rotator.
Choosing the Site
We spent a good deal of time choosing the site. Things like distance from the shack, surrounding obstacles, soil and terrain are all important factors. If the tower is going to be close to the house, remember to allow for your roof over hang, unless you want to do some messy and expensive home renovations later. Also, keep in mind, if you are putting the tower near the house and have a block foundation wall, don't get too close to the wall, or you will have to use forms, or risk about 10,000 pounds of wet concrete in your basement.
The Tower Base Hole
The recommended minimum size of the hole for a Delhi 48 foot heavy duty tower is about 4' x 4' x 4'. The hole must extend down below the frost line. If the tower will be close to the house, this is not usually a problem because enough heat escapes from the foundation to keep the frost level not too deep. Be sure to wheel the soil away, or it will be in the way while you are working or when the base is being poured.
We marked the hole with pegs and with a string this may seem unnecessary but it helps you keep things square. We dug the hole by hand. In my case the hole was located about 2 feet from my house's poured-wall foundation. There was a good reason for this. The home is located on very rocky terrain. I knew that there was sand for the first 4 to 8 feet around the house, going down to the footings. As we dug the hole, we hit rock on the side of the hole farthest from the house. Unfortunately we hit the rock at about the 2 foot mark and it was very tough digging from there. Once you are down in the hole, you cannot use a long handled shovel, so the soil has to be tossed pretty high with a short handled shovel, to hit a wheel barrow standing somewhere above the hole. My strong 15 year old son, was wishing that he was a foot taller. We broke and loosened the rock with a long, heavy, pointed steel bar. Then we took very small quantities of soil and rock at each throw. Also, a lot of the earth and rock was lifted out via pail all in all a tough job that took about 5 hours of hard labour. If not for the rock, we would have been done in about 2 hours.
Decide whether you want the tower base to be below the grade and covered with sod, at grade, or above the grade. Keep in mind that this could become a selling issue for your house later, if the potential owners don't happen to want a large concrete mass sticking out of the lawn. My concrete base ended up about 5 inches below grade which will hopefully allow sod to survive over it.
This may seem obvious to some of you, but you must place the tower with the legs firmly bolted onto it, into the hole, prior to pouring. Be sure to put bolts or threaded rods through the holes at the bottom of the tower legs. This helps anchor the legs permanently in the concrete.
How to Keep the Tower Level and In-Place
This took a while to figure out. What I eventually did was build a sort of wooden cradle from 2" x 4" x 8'. I threaded this through the tower's steel cross bracing (see photos). I elevated the cradle and tower, using 2" x 2" x 3' wooden stakes and combinations of boards and wedges to make fine adjustments. Remember that things will move while the concrete is being poured. It is not easy to totally imobilize your tower against the weight of pouring concrete. Just make sure that you arrange things so that you can quickly and easily bring the tower back on course. I used all sorts of pencil marks, etc. and I am proud to say that my tower is perfectly straight but I must have checked it a hundred times. I used an extra long spirit level to keep the tower square. My tower does not have a continuous taper, like the new Delhi's, so it was quite easy. If you have one of the new continuous taper towers, find a trick that works for your tower. One idea that I heard was to use a particular diameter drill bit as a spacer to keep your level out the correct distance. I suggest that you fasten this in place somehow, so that there will be a minimum of fiddling while you are working with the concrete. Don't be afraid to put a few pencil marks and notes on your tower. Measure everything several times and watch out for Murphy.
There is a lot to know about concrete. I asked a lot of people a lot of questions and concluded that I knew nothing about this area of things. I was told that I should get between a 3500 pound and 5000 pound concrete.
A visitor to this site, John Florian, advises that the concrete numbers 3500 and 5000 refer to the concrete compressive strength in pounds per square inch. 5000 psi has a higher compressive strength and is therefore more resistant to freeze-thaw cycles than 3000 psi. The metric equivalent to 5000 psi is 32.5MPa (Mega-kilonewtons per square metre). Ask also for 6% air entrainment (adds about $10/cu m to the mix cost) to improve freeze-thaw resistance.
I got 5000 pound concrete because the concrete supplier did not charge extra for this, but did charge travel, so what the heck, go for the heavy stuff. If its cool when you are pouring, with a risk of freezing, you may need calcium in the concrete, but use with caution as it accelerates corrosion of the metal legs (according to the concrete man). If it is cold at night, be sure to cover the concrete with straw, and a tarp to keep the rain off for the first night or two. Make sure that your tower does not move for at least 48 hours, and continue being careful, for at least 1 week. When your tower base is poured, try to arrange to have a crown in the middle of the concrete, or at least a small trough in the concrete to drain away the water that settles on the top. If you forget this, phone the concrete contractor to come and cut a couple of ½" deep slits from the centre to the outside to allow drainage. This probably isn't necessary but I noticed that water was puddling in the middle of the base and I reasoned that this may be a problem later not sure. Capillary action of the sod on top of this area probably is just as good. It was a cool day when my concrete was poured, about 15 degrees C, and it was soft enough to scratch our initials in it after 4 hours, probably longer.
If your concrete base is below grade, you will need to place some sort of protector around the tower legs to keep the soil away from the metal. The soil would otherwise hold the moisture in contact with the metal legs and promote corrosion. I thought about using 3 inch ABS pipe, slit in half then taped around each tower leg. I should have taped 8 inch cuffs of ABS up high on the leg prior to the pour but I didn't. I could have unbolted the tower to place the cuffs, but I didn't do that either. I suspect my thick layer of vinyl friction tape is good enough.
We considered all sorts of methods of getting concrete into the hole:
Mixing by Hand
There are several possibilities here ranging from ordering gravel, sand, and bags of dry cement and using a gas or electric mixer, to buying bags of concrete mix.
The problems with this include:
Delivery by Cement Truck
There are multiple choices here. You can have a truck of ready mix arrive, or you can order the type of truck that mixes exactly what you need at your site. Prices vary a bit but about $100 per cubic yard is typical and you can expect to pay extra for delivery and for waiting.
The problems with this include
Delivery by Tow Cart
This method has a lot of appeal in some locations and installations. The open-topped cart holds 1 cubic yard or less. That's thousands of pounds. The cart has only 2 wheels not 4 and does not have electric brakes. The cart has a dump hole at the rear with a lever operated steel trap door. The cart takes a 1 7/8" or 2" ball hitch and can be towed by a gutsy truck. The wire connection is a flat four connector.
Problems with this approach include:
Contracting Out - This was my preferred solution
I found a guy who was a part time concrete contractor. He co-ordinated the entire job, and just let me know the time. Great! He arrived with a gasoline powered, 4 wheel, cement wheelbarrow with a special pouring spout. He had a helper with him. They both knew what they were doing. There was zero waste, zero mess, zero damage. They are not cheap he cost me $350 not including the concrete. He was on site for less than an hour. Easily worth the price in my situation. You have to maintain square of the tower yourself, between pours. His idea of perfectly square and mine differed somewhat, but that was fine, I kept trimming things up and made sure that the tower stayed centred in the hole this is important. The contractor and his helper were very co-operative and helpful and let me do my squaring thing while they did theirs. They even brought a bale of straw to cover the concrete at night.
Grounding the Tower
Grounding is important! The object of the exercise is to provide a drain, away from the concrete base for the lightning, if your tower is struck. We wouldn't want to split that nice big mass of concrete. Nor do we want to make it easy for any lightning to enter the shack. My solid copper alloy ground rods started as 10' long. They are quite expensive and very heavy. Be sure to buy the proper heavy duty bronze clamps for this job. It simplifies the job and gives a good connection. The more ground rods the better and I suggest not less than 3 full length ground rods properly fed and bonded.. I placed a ground rod on each side of the tower, about 6 feet away, and not close to the foundation. I used a very heavy gauge of copper ground wire. Its stiff and a bit heavy and little tough to work with. I buried the wire at shovel depth, from the ground rod to the tower leg, by prying open the ground then forcing the wire down into the crack and then stomping it down. I purchased copper ground lugs which take a ¼" bolt, from Canadian Tire automotive section. These copper lugs are labeled as Gauge #1 and come 2 to a box. I crimped these on to the tower end of my ground wire then soldered them with a small plumbing torch and radio-type resin core solder. First I attached the ground wire to each tower leg, using a tie-wrap. Then I cut the wire to the right length and attached the connector. Then I drilled a ¼" hole in the tower leg, and used a grinding disk to remove the paint from the tower leg at that point. I then used ¼" bolts with lock washers, to attach the lugs to the tower.
I live in the country so I have a good (domestic) grounding system off my 2 wells (the well casing goes down 20 feet). There are two ground rods used by the power system. The wells are connected to the house electrical system by a large diameter multi-strand copper cable about 6 feet below ground level. The house ground is a long way from the shack so I ran a separate ground into my shack through a separate entry point, not alongside the antenna cables. I have attached the shack ground to the house ground and the tower ground.
NOTE: For more info on grounding, please see the link at the bottom of this web page.
Coaxial Cable Feedline
I looked at a lot of cable before ordering mine. I ended up buying a 500 foot reel of 9914. This is a low loss, multi-sheathed, foam dielectric cable, with a solid centre conductor. It is classified as an RG-8 type cable. The only disadvantage is that it cannot continuously flex around the rotator. If I had it to do again, I would probably try to buy the necessary number of runs of the stranded-centre equivalent, rather than make up the antenna coaxial stubs or jumper cables from the antenna to the feed line, just below the rotator. On the other hand, I think that this is fine for dipoles, etc. because the connection point can be secured and the flexing is not localized as it would be with a rotator. Shop carefully, the prices of cable by the reel vary and may be negotiable in bulk. The price is not always logical so do your homework. Electrosonic were kind enough to fax me their current catalogue pages on the appropriate cables and I used that to help find the right stuff. Be sure to connectorize the antenna end of the cables ahead of the time that you put up the tower and antennas.
Getting Cables Through the Wall
The first thing to consider is the size of the hole. I did a little test and discovered that 10 pieces of RG-8/U can easily fit through a 2" hole.
I am not talking about a concrete block wall (which is probably the easiest to go through). I mean a poured solid concrete wall. This is not a trivial exercise. To cut a 2.5" hole through 10" of old concrete which has a lot of stone in it will require drilling with a carbide or diamond core bit and a big heavy duty vibrating power drill. This is a big thing that looks like a small jack-hammer. It can take between 15 minutes and an hour of hard, noisy, work. The equipment can be rented for under $50. If you go this route, you must also decide if your cables will be below or above grade. Below grade is neater looking but has several additional issues including water proofing.
This is not referring to an exterior brick wall. I mean a wall with some sort of siding and wood framing inside. My exterior wall is rather a complex structure. It has a 3/4" thick cedar siding, a layer of Tyvek wrap, a 3/4" thick plywood sheeting, and a layer of insulation. In my case 10" of glass wool type insulation was encountered. I chose to go through the outside framing joist and a another floor joist (I'm sure there is a name for this but it escapes me), because the alternative was to knock a hole through the wall from the inside and then bore down through the floor into the basement. By drilling through the floor joist, I ended up in the basement with no bends, etc. You have to measure very carefully to end up in the right spot. If possible drill a test hole. I was not able to drill a test hole, but was just lucky I guess. I used a 2.5" hole saw and was prepared to use a bit extension but didn't have to because I drilled from both the outside and then the inside. Using an extension bit would be very tricky because a large hole saw tends to bind quite easily with just its regular short bit. An extension bit might be a real challenge. Once I drilled throught the wall and the first joist, I pushed the conduit through the fibre glass, and was able to look up, when in the basement and see a bit of the conduit. I then was able to line up the inside hole with the pipe. Be careful, its difficult to repair mistakes.
If you want to do a good quality job, seriously consider putting your cables through a pipe or conduit, similar to the grey PVC sometimes used for street power entrance to new homes. This will keep your cables neat and manageable, and allow you to better seal the connection into your house. A 2" i.d. translates to 2.5" outside diameter PVC. Your conduit should extend into the tower area. My conduit was above grade at about 18", and I put a 90 degree elbow in mine, pointing down. This will keep the water out and force you to bring the cables down and then up into the conduit. This automatically creates a drip loop on all your cables to keep water from running in. I had some old plastic eavestrough which was taken down last year and was lying behind the shed. I cleaned this up and used it as conduit inside the basement. It keeps everything much neater.
Just a footnote: I thought that 2.5" hole would give me lots of room for cables. For a modest installation, I' d now recommend 2 of these side by side - trust me, you will fill the first one quickly. Why 2 and not a 3" hole? Well you can consider a 3" hole but drilling a large hole like that through an outer framing member of your house may create some mechanical problems. I feel that two 2.5" holes present far less weakening of the framing.
About Ropes and Pulleys
This is the voice of experience speaking. Put all slopers and wire type antennas on pulleys and ropes! I made the mistake of not doing this initially and the result was that when my feedline looked like it was defective, I had to arrange for someone to go up the tower for me to drop the antenna down for testing and to put a pulley and rope up there. Also, my 6m sloper dipoles, while functional, are low in frequency. All these problems could have been avoided with pulleys and ropes.
Use a reasonable sized pulley of about 3'' with a built in turnbuckle. Pulleys can be fastened to the tower in many neat ways. I had U-bolts (clamps) with 4 nuts in the 3 corners of my tower and installed some more of these, further down. To hook onto these after the tower is up - get some special links (stainless) which look like chain links and have a nut-like arrangement. You open the link by undoing the nut, hook the pulley through the link, and the link through the U-bolt fastened to the tower, then finger tighten the nut and it's done. Sometimes it's more appropriate to fasten the rope and pulley on a cross brace of the tower. To do this, use a U-bolt, slide on the pulley with the turnbuckle, then use 2 backing plates and 4 nuts. Sandwich the cross brace between the 2 backing plates - this makes an excellent and easy-to-install mount.
Be sure to use polyester rope or a rope that is covered in polyester. All other ropes deteriorate too quickly! DO NOT USE polyvinyl or plastic rope, unless it is covered in polyester to protect it from UV. Change all ropes every 2 years - Don't scrimp on this!
I use a pulley at the bottom of the tower for each rope. You don't have to do this but it helps minimize problems. I fasten these pulleys to the tower using stranded wire (copper or galvanized) because it is easy to take up slack, and move out of the way when climbing.
As I pulled the antenna up the tower via the rope - I taped the feedline to the rope every 6 feet or so. This takes the weight off the feedline and helps cut down on the slapping against the tower in the wind. When I had the antenna raised I looped the rope around a cross brace on the tower and taped it - there are better solutions. I also have some cleats for looping the ropes around - they look vaguely like clothes hooks - if someone can tell me the correct name for these - I'll reword this note.
There are some good ways to eliminate the slapping of ropes and feedlines and minimizing chances of tangling. You might use a short cross arm through your tower with the pulleys at the ends of the cross arm. This keeps the ropes and feedlines far enough away from the tower to prevent the noise. The cross arm can be fastened to the tower at the crossed braces using either stainless steel band clamps or regular U-bolts, whichever is mechanically acceptable to you.
Results of the Work
My antennas are pretty basic. They include:
The yagis work out very well, they are really sharp and I am very happy with them. The 6 m slopers gave good results but they turned out to be low in frequency. I did not yet have my MFJ259B when I cut them. I worked many DX contacts with them and some aurora. They are not real great performers for local work but when the band is open, they work well.
On June 27th, 2000, Mel (VE3OJN) brought the 6m slopers down off the tower and we recut them. We also rearranged their distance from the tower. At least they now resonate on 50 MHz not on 46 MHz These three 6m antennas connect to a 6 position coaxial switch. When I'm on 6m, I use the coax switch to select the best signal (on receive). I have discovered that the sloper favouring the south is generally good for medium and long haul points south, east and west. The sloper favouring the north is good for aurora or also to the east and west. The horizontal antenna aligned east-west seems to work best for local contacts.
The HF antenna, initially had a bad feedline, but since replacing that, it is giving excellent results. I have a loud buzz on 75m, which sounds like power hum but is definately coming in on the antenna.
The discones give good results on vhf FM, and acceptable results on uhf FM - the SWR is fine - they don't get out all that well, but then you have to remember that discones are horizontally polarized. I don't think that I would use them again - but I will say that they give low SWR across their range and are good for testing just about anything above HF. And ..... they are really a pain to mount. Don't worry if your discone does not have a vertical whip - neither of mine have a whip. That whip is more for looks than operation. If you find facts to prove otherwise please let me know.
Early in May just after my FT847 came back from Yaesu, the UHF antenna packed it in. As soon as I keyed it, the radio would "take off and do its own thing". I don't know how else to describe it. The output power would go to FULL, regardless of the fact that I was on SSB and had the audio and rf output level cranked all the way down. Mel (VE3OJN) climbed the tower on June 27th, 2000 and brought the antenna down. He noticed a bit of corrosion in one connector, and also some corrosion at the hairpin/T match at the point where the hair pin solders on to the connector. We resoldered that and Mel showed me another neat trick. Place a tiny rubber "O"ring on the post of your PL259s, then tighten gently with pliers. This adds moisture protection and prevents the connectors from working loose through vibration, etc. Very handy little trick! When we put it all back together and Mel did the tower climbing trick, Eureka! I was back on UHF.
One more comment. If you are doing antenna work be sure to buy, beg or borrow a MFJ259B or equivalent antenna analyzer. I own one now and don't know how I ever put up antennas without this box. It tells you a great deal about impedance and resonant frequencies and puts all the theory that you ever learned about antennas, into practice. If you are going to own any test equipment, this is a good 2nd choice after a multimeter. I'm not promoting MFJ here, but they do have several versions of this valuable tool. I hear AEA also makes a very good analyzer, but i've not used that one. btw - if buying the MFJ unit, you don't need the GDO coil, just wind your own, almost anything works - it's just a coupling loop.
Sources of Stuff
All prices are Canadian $$$ and all locations are in the Ottawa area.
PicturesClick here to view some pictures.
Infernal Tower - Update 2001
I like to plan events like tower changes well in advance. I mean months in advance. I talk over a lot of my ideas with my colleagues, and my family because most of them have valuable input, and I seldom know what I am doing when I start. I don't climb my own tower, so I have to co-ordinate with a good tower guy, and they are tough to get on short notice.
In the early spring, I decided to add a loop yagi for 1296MHz, on the top of my mast; to replace my 3 element 6m antenna; and to generally rearrange spacing on the mast. My original mast pipe is T6 1/8" thick aluminum. It is 12 feet long, 5 feet below the top bearing, going into the rotator and another 7 feet above the bearing. This was clearly not long enough to accomodate the extra antenna with good spacing all around. Besides, I have tall sugar maples and hickory trees in all directions, with some useful gaps to the south and west at the 60 foot height. So I decided to replace the 12 foot mast pipe with a 16 foot pipe which would give me 5 feet in the mast and 11 feet above the bearing.
I wanted a loop yagi for 1296 at the top, followed by a yagi for 432, followed by my 2 meter yagi, and finally a new 5 element beam for 6m. This new arrangement meant that all existing antenna jumpers would have to be replaced. These flexible coax jumpers, made from 213, run from the antenna to the area below the bearing where my stiffer feedlines start. I might have been able to reuse some of the old jumpers but chose for reliability, to redo them all.
For the 1296 MHz loop yagi, I was concerned about the loss of 213 and so considered running the more rigid hardline, heliax or LMR down the mast pipe to the bearing, then using a short flexible jumper around the bearing, then back to the hardline. In the end, after discussing with several experts I abandoned the idea. All those connectors at 1296MHz could introduce as much loss as the 20 feet of 213, so I decided to use 213 from the antenna to below the bearing, and LMR400 the rest of the way - yes some loss, but acceptable for a beginner.
I made a chart for each antenna showing the length from the connector or terminals (on the antenna boom) to the mast, the distance down the mast to the bearing, plus 4 feet of cable for the loop around the bearing. Measure this very carefully! This was my chart:
I also decided to change the mounting arrangement for the discone antennas. First of all, I had 2 discones up there and since I only need one, I decided to leave the other one off. Secondly, I originally made a large U mount with 1" copper pipe. Copper is too soft and heavy for this type of use and started to sag. So I decided to replace that with electrical conduit which is inexpensive and very strong
Get the Material
The new mast pipe cost me $81 at Ridalco. Reasonable I think. And the new 5 element beam for 6m is described elsewhere in these pages.
Since the existing antennas and mast pipe are coming down anyway, have a spare bearing all greased up and ready, just in case. I bought a rebuilt bearing in impeccable shape at a flea market for $40 (excellent price).
Before you start the actual tower work, be sure you have on hand:
Mounting the discone using a Z pipe
I decided to replace my 1" copper U Pipe (for mounting 2 discones) with Z Pipe made from a 10' length of 1" electrical conduit (under $10 CDN at Home Depot). It is very strong, a bit heavy but much better than the copper. I had an electrical contractor bend my pipe into a Z shape for me. I suggest a 90degree bend at about 3 feet, a straight section of 4 feet (this will end up parallel to the ground and sticking out from your tower), and another bend in the opposite direction to the first, 3 feet from the other end. You can use this arrangement to mount a variety of antennas, and even a small rotator and antenna (with less than a 4 foot radius, of course). The tower guy found this arrangement much easier to work with than the earlier U frame. Discones are bad enough to assemble when standing on a tower, so anything to improve the pain is good. The Z pipes are held to the tower using 2 or three 4" stainless band clamps.
You must prepare ahead of time as much as possible. Tower day will be a very busy day - I promise you - so do every possible thing ahead.
I premade all the feedlines (jumpers) which go from the antennas down to the main feedlines heading down the tower. If you are not quite sure, leave the bottom connector off and leave extra coax - a few feet of coax is very inexpensive and besides you can always use short pieces in the shack or workbench. TEST! TEST! TEST! each and every cable carefully for shorts, opens and intermittents.
If possible, when you are getting ready to rearrange your tower, set up a tripod and 6 foot mast pipe on the ground near your tower. This is useful to help you visualize things. I bolted all my new antennas to this mast and tested them first with my MFJ antenna analyzer and then with a reliable SWR meter and a radio (another use for my already over-used FT-817). Because of the proximity to ground it is not a perfect arrangement but not a bad test set up. Also this tripod arrangement is invaluable when you bring down the existing antennas to check them out.
The finale was on June 5th, 2001, a cloudy, occasionally breezy, and occasionally drizzly day.
Before you disconnect any cables up on the tower, be sure that you label the existing cables. I like white vinyl tape and a permanent marker. Once you get all the old stuff down on the ground, carefully checkout all antennas that you will be re-using. I cleaned them up, put a radio on them with a borrowed SWR meter, and made sure everything was perfect. Then we started the process of getting all this aluminum back in the air.
There are at least 2 ways of getting the whole thing together: build it while you are on the tower, or build it on the ground. NOTE that whichever method you use, the last and heaviest antenna is mounted once everything else is already in place. This bottom antenna is usually easily reachable while standing comfortably (huh) on the tower.
If you choose to assemble things while you are up on the tower, it is a slow process, I think. It usually means moving the rotator, slipping the new mast pipe all the way down, mounting the top most antenna, then lifting that up, clamping with a visegrip, mounting the next antenna, pulling it up, clamping with a vise grip, etc., then eventually raising the whole thing, replacing the rotator, and finishing off the lower antenna. Slow and awkward I think.
We chose to build the new antenna/mast configuration on the ground. We held up the mast pipe with an aluminum ladder and mounted all except the larger, heavier, 6m yagi. All feed lines were fastened in place and connectors were prepared (barrels, etc). Be sure all feedlines are clearly labelled. This work went very quickly and smoothly because there was plenty of help and we were all standing firmly on the ground.
Once the antenna arrangement is built up on the ground, it is a real challenge getting it up to where it is supposed to stay. It is heavy and awkward, and a bit delicate. The technique we used was to attach a gin pole to the top of the tower, with a pulling pulley at the bottom. The rope for the gin pole goes up through the bottom of the pole. Now there are a lot of tricks involved in getting this all to work. You have to tie the rope to the antenna arrangement at the right place, and the gin pole has to be tall enough to hoist the mast pipe, allow the tower man to swing it into place, and lower it into the rotor. Our gin pole was too short, so we improvised. It turned out that our gin pole would just slip into the old 11 foot mast pipe that we removed. We fabricated an S hook for the bottom of the gin pole extension (this was small enough to let the pull rope pass by - the second time we built it). We lashed the gin pole and extension into place using 4" band clamps that would later be used to hold the Z pipe. Then we hoisted the whole thing up, with only a few nervous moments. And then when we were swinging the mast pipe into place we had a panic.... would the mast bottom clear the top of the tower and drop into place? Well since it was raining and windy - we doubted that this would work, but it DID with less than 1 inch to spare. Whew! After that it was clear sailing all the way. Be sure to restore the antennas pointing exactly in the same direction as when you took them down (so your rotator still indicates the same).
Note: This info is important so I have mentioned it here and also in the area on antenna construction. I thought it worth mentioning that I have found 2 products which are vital for successful weather proofing of connections. These products are quite expensive but well worth their cost:
I like to tape all coaxial connections in feedlines with a soft, sticky, rubber tape. This is non-vinyl tape which is very pliable and sticky and totally seals against moisture if properly installed. This tape's offical name is 3M Scotch 130C Linerless Rubber Splicing Tape and it is available from Westburne Electric located on Michael St. (where it runs parallel to Innes Rd.). Cost is about $15 per roll and one roll will last a long time. Stretch it slightly when applying .... something like black vinyl tape. This tape must be installed dry but it has a far better temperature tolerance than vinyl tape.
The second product is a black, liquid rubber substance which I coat all screw terminals with. This material is difficult to remove, if later necessary, but it is an excellent sealant for screw terminals, to prevent water penetration, corrosion, and electrolysis. Put 2 coats on. It dries within 5 minutes and can help ensure that your antennas keep working trouble free for years. This product is called Star brite Liquid Electrical Tape and is available from Gervais Electronics on Industrial Ave in the east end of Ottawa. It comes in a small, round, yellow can, with a brush/applicator in the cap. One can will last you for years. It cost me $11.50 in October, 2001. Recently available at Canadian Tire for about $6 a can. Canadian Tire also sell a tape called plumber's tape, I think, which is similar to the rubber splicing tape.
I used all antennas except the discone in the recent June VHF contest. The 1296 loop yagi, at about 60', exceeded my expectations. I worked FN12, the other side of Rochester, with 10 watts and some very bad CW (on my part). The 70 cm and 2m yagis worked as well as before and maybe a bit better. The 6m 5 element is a very big improvement over my 3 element. It is very effective on local contacts - much better than any of my dipoles (which I always felt were pretty good). On DX, I still find the noise from the yagi higher than I like, but I have a very high electrical noise level here. The dipoles seem to work better for some of the DX while the beam is noticeably better for other contacts. Interesting! The discone works about the same as it ever did - its for FM.
Thanks to Mel (VE3OJN) for his daring deeds on the tower. He was up there for at least 6 hours with only minimal breaks. Also thanks to Les (VE3FHU), whose expertise was invaluable, and thankyou to my wife Eva and my son Stephen who both were called on for assistance during some of the more exciting moments.
I hope that this information is both enjoyable and informative. The secret is - don't do it all yourself - then you can share the blame if it doesn't work (hi). And remember .... the licence says (or used to say - when we still had a licence) Amateur Experimental Station.
Infernal Tower - Update 2002
In October of 2002 I discovered that I had a feedline problem on the 6m 5 element antenna. Well actually it was a connector. Once I replaced that connector the performance of the 5 element 6m beam improved enormously to the point that I only use one of my slopers now for repeaters and mobiles and will be taking down the other sloper and dipole and reusing those feed lines. The 6m antenna design is shown elsewhere on my web pages.73.