Sunday, October 16, 2011

HF Contesting on a Budget.Ideas, Hints and Tips

Of all the money spent on a contest station, the most worthwhile is in the area of antennas. The old adage 'If you can't hear them, you can't work them.' is especially true, and can also be turned around to read 'If they can't hear you, they can't work you.' Contest sections limit the power you can use, in any case you can't go above your license limit which here in Ireland is 150w DC input, so in order to get your signals through the pileup as well as hearing that exotic DX multiplier, increasing the antenna-farm is the only way to go.
If you take a look at some of the contester-websites, you'll see huge towers with stack of yagis pointing in every direction. But as few of us have the land or the cash, we need to think of other ways to go. First of all, you need to define your objectives, in terms of which bands you want to operate from, and which areas of the world you need to cover. It is nice to have a big signal on all bands 160m-10m, but if resources are limited, you could take the bands one at a time, and spend a year operating all the contests as a single band entry, and then the following year choose another band. This way you could have a great monoband antenna where a multiband setup isn't practical, as well as needing only one feedline and support.

 To rotate or not to rotate ?
The big contesters know how much time can be wasted waiting for the beam to swing around, so they generally have fixed antennas on all of the main ham areas, and use the rotating beam for multiplier catching. If they can cover the areas where most of there signals will come from, and be able to switch between them quickly, they are happy. From the budget contester's point of view, this idea is something to stick with too. Have you seen the price of rotators lately ? The ones that can handle those big beams are pretty pricey, so doing without is worthwhile. A lot of contests are based on specific areas of the world, so if you've got your antenna pointing that way, and its beam-width is not too narrow, you'll be as good as the next guy and won't waste beam-turning time either.

 What antenna-type to choose ?
This depends a lot on your situation, but there are a few ideas that may be useful. The big contesters stick to yagis because they can buy them off the shelf, you can fit plenty on a tower, they don't need adjusting during the contest, and their gain, front-to-back ratio and beamwidth all make them a great antenna to use. The downsides are the big support towers needed, the rotators, and of course the price. Just check out the price of a monobander or a non-trapped multibander and you'll see what I mean. Homebrew monoband yagis are a good possibility if you can afford the aluminium tubing, but for best value its best to stick to wire which is cheap and easily obtainable.

 Single or multiband ?
When home brewing antennas, a monobander is generally easier to construct and get working properly. Don't fall into the common trap of using traps ! They are poor performers in anyone's book, reducing gain and bandwidth; they are best forgotten about. Better to use multi-dipoles attached to the same feedline and supports, either in a fan or using multi-core cable. Better still, a big dipole fed with ladder-line that can be used on many different bands - more on this later.

The idea of obtaining a multiband antenna by putting seperate monoband elements on the same support structure is valid for other designs too. The most obvious is the quad, with its seperate elements on the same spiders, but yagi manufacturers also go this route as well. Both of these work better with separate feeds for each band, or a relay box to choose the one you want, though there is one antenna, the log periodic that keeps everything on the one feed line.

 Rotatable options.
If you are determined to go for a rotatable antenna, then the best value has got to be the quad. This antenna is formed from one or more full wave loops per band, and makes a great contest antenna. Its good points are that its a loop so its low noise, there's worthwhile gain and F/B available, and they are not too difficult to make yourself, especially if you don't try and pack too many bands on the one framework. We even have a quad expert here in Ireland - EI7BA down in Cork, so check out his excellent website and see what he has to say. Other rotatable wire antennas include the ARRL's Telerana, which is a log-periodic and hence multiband; and the VK2ABQ tribander which is useful for those with a limited space.

 Where's North ?
Once you have your antenna up, its important to make sure its looking in the correct direction. To work that out, you'll need a Great Circle Map centered on your location. You can pick one up in my Download section, or check out the Links Pages for software to make your own.
You'll also need to know where true North is. People can get mixed up when it comes to finding out the correct magnetic deivation for your area, then applying it correctly, so a simple solution is provided by Pete, N4ZR, who says 'Get your local paper and find out when local sunrise and sunset are. Split the difference. When that time arrives, go down to the tower and see which way its shadow points. That's true North.' Simple when you know how ! Alternatively, if you are determined to be more technical, follow Dave, AA6YQ's advice - he says 'If you know your QTH's latitude and longitude or grid square and your PC's time is accurate (using a freeware internet-accessible atomic clock like AboutTime, DXView will tell you when the sun is exactly true north of your tower - see If your rotator has a PC interface, DXView will control it for your, displaying your beam heading and the solar terminator on a world map. And its free.'

Fixed Wire Beams.
Some very useful fixed wire antennas with plenty of gain can be made for small amounts of money. Most of the handbooks have designs in them, so you don't have far to look. A vee-beam is very simple and effective, and could be mounted on a single support with the arms sloping down to near ground level. Its bigger brother the rhombic is used by some, and there are websites where you can find out more information - see my Links page. However, they may not be the choice for everyone; here's what K6HI says on the subject:
Wire yagis are a possibility though information is sparce; Les Moxon suggests that good value can be obtained using long, wire-yagis made in inverted-vee form and requiring only two supports. Likewise, the wire log periodic is cheap and easy; some have made inverted-vee versions or even vertical log-periodic beams that would require just a single support. W4AEO wrote a great series of articles on wire LPs for HamRadio magazine in 1973.

How about a very simple wire antenna used by a lot of the top contesters ? We're talking Beverages here, and apart from the matching transformer, they are about as simple a receive-only antenna as you can get. They are cheap to construct, and as long as you have the space, an unbeatable option for the LF bands. You might think you need miles of open grassland for good results, but many use them through woods etc with great results, and if you've a wood next to you, thats the supports taken care of too - just buy a bag of electric-fence insulators from your local farm-supply store. If you live in the city, buy a drum of black wire and run it along the tops of fences etc. when the neighbours aren't looking - a 'stealth-beverage.' For many, the beverage is a seasonal antenna, making its appearance for the autumn contest season and disappearing in the spring. W2UP suggests a simple support system, consisting of 3ft lengths of rebar hammered into the ground. A length of 1.5" PVC pipe is slipped over the rebar. At the end of the season, the rebar is pulled out of the ground and saved for next year.

 Receive Loops.
Not got the room for a beverage ? How about a receive-only loop for the LF bands. This can easily be made at home using bamboos to provide a 6-8' diameter support. Because its a closed circuit, its a lot less susceptible to noise than long wire or vertical, and its rotatable too, which can be very useful for nulling out the interference and improving the S/N ratio. You will find a site with homebrew loop information on my Antenna Links page, or just have a look in one of the handbooks.

 Sources for wire.
The dealers would have us buy that nice drum of hard-drawn copper for all our antenna projects, but a variety of other wire can be used as long as it suitable for the intended job. A 160m dipole made from standed wire would soon stretch, and snap in a wind, but used for HF antennas it might be OK, and for buried radials, just the job. Secondhand wire can often be found at scrap dealers and bought for little more than the cost of the copper content. Utility and telephone company often replace cables which would make ideal antenna wire. Sometimes, the multicore cable has additional steel cores, which are great at stopping antennas stretching over time. Sometimes its not in the right lengths, but there's no law that says an antenna has to be made out of one piece of wire. Knot it well, solder the ends together and make good the insulation with a piece of tape.
Still on the subject of wire - Have you seen the price of rotator-control cable ? There's no need to buy this stuff, as any multicore cable will do as long as it has sufficient current-carrying capacity. For long runs, house wiring cable can often be cheaper. The same applies to preamp power cables, and other control cables for remote switching etc.

One antenna-type not to forget is the vertical. For LF contesting, paticularly on 160m, a top-loaded vertical is the antenna of choice, but even on the higher bands, a vertical with its low angle of radiation can still be useful budget antenna. We are not talking anything fancy here - a vertical is a piece of conducting material suspended vertically. It can be self supporting aluminium tubing, old copper pipes or electrical conduit; and who can forget the Bean-Can vertical, which as its name suggests was made by soldering together sufficient baked-bean tins to get the correct length.
Any vertical needs to be insulated from its mounting points, which on a vertical supported at the base can be done by surrounding the section thats clamped with an old piece of polythene water pipe, or if we are talking about a guyed free-standing vertical, just sit the bottom end in an old coke bottle. If the upper portions are guyed with plastic rope or bailer-twine, you won't need insulators there. Verticals can also be made of wire, supported by a tree, or from the guywire of a tower. Some have even used kites and balloons to support a big LF vertical although the Aviation Authorities generally impose an upper limit on this.
You could make a vertical array by phasing two or more for some directional gain, and the 4-square array, which as its name suggests is an electrically steerable array of four fixed verticals, is used by even the biggest of contest stations. For the budget contester, its important to remember that dollar for dollar, a phased vertical array is a much better bet than a big LF beam at a sensible height and suitable tower or rotator. Spending a few dollars on wire for the radials doesn't seem so bad any more, does it ! The more radials, the better.

The feedline of choice these days is of course coaxial cable, or 'coax'. There are many different types available, but buying cheap coax is not a good idea due to the losses involved. A budget contester should not cut corners here, but stick to at least RG-8U of good quality. Hardline is even better - just check out the loss-tables in most amateur radio handbooks and find out where those DX signals are disappearing. There's no point losing those hard-earned dBs from amplifier or antenna down a cheap bit of RG-58. Here's something to ponder on - for the budget contester wishing to improve his station, the 'dBs per dollar' figure for good coax is a lot better value than a new linear amp or yagi. Be careful also about second-hand coax. It could be a good deal, but could also be a complete waste of time if worn, damaged or corroded. Check it out first, or you'll be wasting your money.

 Reduce your Feedlines.
With the price of good quality coax being what it is, an option for those with antennas grouped together is a remote coax switch, which can be purchased or home-made. The control cable will be a lot cheaper than multiple coax runs, and as long as the switch is well constructed, will have a minimum insertion loss, especially at the lower frequencies used by HF contesters. Whilst on this subject, Dick, WC1M suggests a home-made remote switch box for your antenna rotators as well. Not only are you saving on cable, but you only need to purchase one controller. I use this idea, though switched at the shack, and the switching is easy enough to do, though I would recommend powering down the controller when switching between rotators.

 Open Lines.
Before the days of coax, everyone used open-wire lines to feed their antennas. Its disadvantages are that is not always easy to get in and out of the shack, it must be suported away from the ground and metalic objects, its hard to use on a rotating beam, and it requires a tuner at the transmitter end. However, don't give up just yet ! It has a lot of advantages too, such as low loss over long runs or high frequencies; it handles high power well; but best of all for the budget contester, its very cheap.
The construction requirements are two wires separated by insulating spacers. The wire doesn't have to be anything special, and its not under any tension either. The insulators can be home made from any number of materials. A few ideas I've come across are wooden dowells boiled in wax, old ball-point pens, strips of plexiglass/perspex, of lengths of electrical oval conduit. There's nothing magic here, and it works great. Consult some of the older handbooks for ideas about using and routing it, and aim to keep it about 10" away from anything else.
For the budget contester who lacks the cash or real-estate to go for resonant antennas on each band, a doublet, as big and as high as you can get it, fed with ladder line is a great multi-band proposition. The tuners are easy to make, and if you are worried about speedy band tuning, try K1ZX's idea of cutting out a piece of card so that it slides over the shafts of the variables, and hold it in position with a piece of tape. You can then mark the card with the correct adjustment positions for each band. He suggests a different colour pen for each band to save confusion. This idea works great for linears and valve transmitters as well, when you don't want to permanently mark the front panel.

 Normal People.
So, you've got this far, but are still not convinced you can do without that stack of monobanders ? Well, the following might be of interest you, extracted from a survey in the RSGB's 'Radio Communications June 1992' magazine, based on a poll of all UK stations on the DXCC Honour Roll at that time....
Some had very small lots : one had a garden only 16ft square behind his house.
Approx 50% used three element tribanders. Those who had moved to quads reported they were not going back. All quads except one were two elements - the exception was the famous G3FXB quad, which had three elements on 20, four on 15, 10.
Antenna height: Only 3% used antennas higher than 60ft. 40% used 60ft, 30% 40ft, and 14% 30ft.
Only three used directional antennas on 7 or 3.5Mhz. Only one had a rotary on 7MHz, none on 3.5.
Good results were reported with very modest whips etc. on 7MHz. The consensus was that one could do well on 3.5 and 7MHz with simple antennas, but that it was necessary to experiment with whatever will fit on the site until it is discovered what works for you.

So, quite a lot can be done with modest antennas. Don't forget, these weren't occasional operators, they were operators on the DXCC Honour Roll ! Food for thought, I think.

 Masts and Towers
A means of support for your antenna is required by all but the vertical-user, and is often thought of as being the major expense in an amateur contest station. A glance at the websites of some of the top contest stations will show fields full of huge rotating towers and the like; much money must have been spent here; but for the budget contester there are alternatives to be considered.

 How high is enough ?
Given the choice, the sky would be the limit, but for practical purposes the height of your antenna depends on the frequency in use. If you want any kind of efficiency and low angle radiation, you should aim for at least a half wavelength above ground, i.e. 66 feet on 40m, 33 feet on 20m etc. For low angle radiation of 10 degs or less you need to be at least 1½ wavelengths high. Is it worth increasing an existing support tower ? According to K8JP, a general rule on height increases is that 50% increase is worth the increase. Less, don't worry about it doing it.
As can be seen, the lower the frequency, the higher up you need to go, so for those on a budget, a single band entry on the higher bands is a more sensible proposition. A 33 or 40 foot high support is not very difficult to acheive using readily available materials such as scaffold tubing or timber. A tree is often handy to most shacks and can be used at little cost. Some amateurs have mounted their antennas IN the tree - for instance a delta loop works well and seems little affected by summer foliage. If your tree is too small you could consider extending it - I increased the height of a pine tree in my garden by 10 feet using a 17 foot length of timber which brought the total height to 60 feet and made it an excellent support for my full wave 80m loop - a great antenna.

 Mast or Tower ?
When, you might wonder, is a tower, i.e. a multi-leg structure, necessary and when will a mast, i.e. a single leg structure be sufficient. I am not an engineer so I can't give a theoretically qualifed response, but just from my own experience its suprising what can be acheived with a minimum of resources. I obtained a mast-base hinge; a device that has two sockets for a 2" pole set 90 deg apart and hinged to a flat base. A 20' scaffold tube went in each; one was the mast and the other the gin-pole. On top of the mast went the rotator, above this another pole to a rotating bearing. A 3el 20m beam on the top, a lot of guy ropes, and there you have it - a beam in the air for very little money. Its as fiddly as hell to erect and takes all morning to do it, but its cheap, strong, and it works. This is a rather extreme example, of course, and for someone requiring a single mast to support a wire antenna, life is a lot easier. Plan the job thoroughly, assemble sufficient helpers and you'll soon be on the air.

 Homemade Towers.
There are few resources available on the home construction of masts and towers, probably due to the worry of legal action in the case where someone who has followed your suggestions and since had an accident. Indeed, for legal reasons I must state that the ideas on this website are only meant AS ideas and should not be used as any form of construction guideline. But due to the cost of commercial towers, as well as the shipping charges, many amateurs have had to homebrew their own supports or enlist the services of a nearby engineering company. Here in Ireland, our own EI7BA, of homebrew quad fame, has some information about a simple tower design that he uses on his website, whilst over on the other side of the world, VK4VKD has a website describing his designs, and he even offers a video (PAL format) to help you along.

 Value for Money.
The best value for money, when it comes to towers, has got to be the guyed tower, made from tower sections as required. The disadvantages are the real-estate required for layout of the guys, the difficulties of getting an antenna up the tower and past the guys, and when stacking is on the agenda stopping the guys clashing with the beams lower down the tower. However, the cash required and the visual impact of a self supporting tower over, say, 80' may convince many to go the guyed-tower route.

The guidelines when considering any form of home construction must always be based on safety. There have been too many cases of amateurs falling to their deaths from towers, or for poorly construsted towers collapsing for this to be ignored. Anyone making a crank-up lattice tower for themselves would have to be very careful indeed,as there are many areas where disaster could strike, but a simpler guyed or tiltover tower made from suitably strong materials should not be outside the realms of possibility for the competent home mechanic. If in doubt, ask your local engineering company to come up with something - it could still be cheaper than shipping in a ready-made one.

Steel has got to be the material of choice, as its strong, long lasting if protected, cheap to purchase and easy to weld. Secondhand steel is readily available - just visit your local scrapyard and see what they have on offer. Aluminium masts and towers are very popular due to weight and corrosion-resistance; the big drawback here is the price. Many amateurs have made wooden supports - a look through the handbooks should bring forth some useful ideas. OK, so it might not last 100 years, but then neither will you. At least a wooden mast is something that most people could attempt with few specialised tools. Some people suggest other mast material, such as fibre-glass fishing poles or PVC pipe. All of these will do as long as the design is a sensible one - the key point for the budget contester is to use what is available readily and cheaply, and to always be on the lookout for other possibilities coming your way such as a discarded utility pole or a job-lot of scaffolding. Don't forget the military-surplus stores, which often have masts and mast-sections on offer.

 Guy Wire and Rope.
A variety of materials are available for guying your mast or tower, and the choice of which one to use, as well as the size of that material, must be made VERY carefully, as life and property could both be at risk.
For a temporary installation of a field-day mast, Polypropylene rope is one of the cheaper options, and can often be purchased for a reasonable sum at a Farmers Cooperative store or Discount Mart. However, as Dr. Barry L. Ornitz WA4VZQ points out, you should bear in mind that "..... as well as its tendency to stretch, Polypropylene rope has virtually no ultra-violet resistance, and in bright sun, you will begin to see degradation within months. It will generally fail within one to two years depending on load and local climatic conditions. For longevity, polyester (such as Dacron) rope should be used. Nylon is also suitable if you live in a area with little industrial activity, which produces acid smog. The best colors for UV resistance are bright white (loaded with titanium dioxide to reflect the light) or black (loaded with carbon black to absorb the ultraviolet)." There is more detail on this subject to be found in the 'HF Contesting>Tips and Techniques' section of this website.

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