Thursday, June 23, 2011

Fun with Antennas - Part 1

Having been licensed for a number years I like many have gone down the commercial route in both rigs and antennas, buying various base units from Kenwood’s, Icom’s to Yaesu’s and using different commercially made antenna’s having little or no patience to build my own.

A while back I took a break for a year or two and came back in to the hobby with a slightly different attitude, especially with regard to antenna’s and understanding how they work. Having sold all of my equipment I had to start all over again and in my search came across a local radio amateur who was selling a Yaesu Ft990 belonging to the late Frank Watts G5BM.

The legendary frank watts G5BM
Frank was a bit of a legend round these parts, a confirmed CW enthusiast I actually visited the legendary Frank years before when starting out on CW. I watched him do a few qso's and was amazed at his speed and light touch, he was a master of all types of CW keys. He was also kind enough to show me all his homebrew equipment including a fair few antennas he had made over the years. I always remember him saying, “You may own a nice rig but remember it is the antenna that does most of the work”.

Remembering our conversation all those years ago got me thinking that I should really start making my own antennas, partly because of cost and more importantly because I could learn another part of Amateur Radio. I figured the best way for me to learn was to start tinkering and having a go at building a simple antenna, that way I get the satisfaction of  knowing that when I hit the jackpot of a DX station I’d  know that I’d done a lot of the work to make it all happen!

Since having the break I had moved house and with a nice new garden to play in I could start afresh. The whole plot was nearly half an acre and the amount of the garden I had negotiated with the members of my family for radio work was approximately 90’x 50’ which gave me plenty of room for some reasonably sized antennas. At one end of the garden is a silver birch tree about 40’ high which could give me and ideal spot to hoist a dipole and at the other end I had managed to raise an old aluminium scaffold pole with an extension to give me a similar height of about 40’. If necessary I could also use the roof apex of the house which again was around 35’.

Whilst searching around in the shack I found I still had an old Carolina Windom 80, it was very long but with a bit of planning it would just squeeze it in the garden, however it would definitely look odd and out of place. So I did some research on the web and came up with the idea of reducing the size to make a Carolina Windom 40; 66’ in total, which would fit snugly down the length of the garden. After much measuring and re measuring I did the deed and cut the antenna to its new length 25’ short and 41’ long and reducing the size of the vertical element from 20’ to 10’. Borrowing an MFJ 259 I did some quick checks and trimmed each side to get a reasonable SWR reading of 2:1 for the whole of the 40m band, further checks showed acceptable SWR readings for 20m, 15m, and 10m and using my tuner I could happily use 30m 17m and 12m with no major problems. 80m could be tuned up with patience but since I rarely used that particular band I thought I could live with this problem. All in all the Carolina Windom 40 was a good antenna and produced great results but to be honest it still felt like I had cheated and was still using a commercially made antenna.

I have to be very careful when it comes to antennas, I happened to live in an area of outstanding natural beauty (the Cotswolds) so there is no way local residents are going to enjoy seeing a very high antenna or tower! What I needed was to build something that would happily fit in the garden be fairly discreet and be a true home made multi band system.
I trawled over the internet looking at various designs of multi band antennas, seeing what would be relatively easy to build and more importantly put out a good signal.

There’s no question that before the yagis and beams the old boys had some brilliant and intuitive ideas when it came to antenna design. I came across two easy designs; the classic random length dipoles fed with open wire feed line and the W3DZZ a simple a multi band trap antenna. The W3DZZ was cheap to build and a reasonable size to fit neatly in the garden. More importantly I could learn about traps, something in my early radio days I didn’t really understand and yet are actually quite simple to build, especially coaxial traps.

Taking the sensible route, I decided to start with the basics and chose the random length dipole with an open wire feeder which was even easier to build. I had some spare 14 gauge wire and trimmed to a half wavelength for 40m. Another rummage in the shack and found some 300 ohm ribbon cable. Within a short time I had completed the dipole and connected the feeder, now to connect to the rig; but there was a problem; my ATU would not accept the open wire feeder. Back to the web I searched frantically for an answer, how to transfer a 300 ohm feeder in to a 50 ohm cable for a connection? I quickly started learning about baluns; this is what is so great about the internet, by the end of the day and after some experimentation I had built my first 4:1 balun. I connected up my newly made balun and plugged the coax in to the back of the tuner and switched the rig on, hey presto I was up and running and within minutes was talking to a Frenchman who was giving me a good 5/9 report.

Pleased as I was, this antenna was definitely fine for local European traffic but was quite weak when it came to DX. Within days of realising this I immediately set about building the W3DZZ hoping that I might have some better luck.  Following instructions from various websites the coax traps were fairly easy to build although getting the coax to right length sometimes proved a little tricky. I used an MJF 259 to check that all was well they tuned up nicely, 1:1 right on the cw frequencies I required. For my first attempt the traps worked well on 7 and 3 MHz and I was getting some great contacts on these bands but disappointingly although titled a multi bander it was very quiet on the other bands compared to the Carolina Windom and the random dipole.

I was still certain that I could build an antenna which was better than the Windom and so once again I did some research on the internet and quite by chance came across the Mystery antenna. This very simple to build antenna used a mixture of coax and 14/16 gauge wire, it only took me a day to construct and after a quick tune and trim I soon had it hanging up in the Silver birch as an inverted vee.
First results were fairly good and unsurprisingly matched against the W3DZZ it was down on 3 and 7 MHz  by a couple of Db. But it worked extremely well on 14 MHz and as a multi bander it easily matched the Carolina Windom, at last I had built something that was near to matching a commercially made antenna.

Morse Code - Come Over to the Dark Side

It’s outdated, it isn't that easy to learn, it can be a real pain! 
But if you perceiver Morse code can be a real reward that I guarantee will give you hours of fun. It's the mode that can get through the static, the QRM, the QRN and other interference. Its the mode that will get you across the world with 5 watts of power, you'll never master it because your always learning it, but it's the mode that does become the most fun to use!

I think it took me about 6 months before I could say I was actually proficient at CW, which means I could understand and reply to a conversation of perhaps 12 words per minute. Like all learners I struggled, god knows how many pencils I broke in frustration, but I had an excellent teacher who had the patience of a saint and just told me to keep going, practise each night, don't give up. Each operator is different, some will pick it up easily, others will really struggle; it is after all learning another language. 

But once you have mastered CW it is a great form of communication and I find it fascinating, simply because I am having a conversation with someone in a completely different language that a lot of people don’t understand. It’s a bit like someone speaking Gaelic or Welsh, it’s actually a rare form of communication and one that should be treasured. Also in radio terms when other forms of communication are unable to get through Morse code can be a good last resort.

Some operators use paddle keys others use straight, some fast some slow and some can be mind bogglingly bad and others can make the code sound like a wonderful tune. The bad ones will make you shake your head in disbelief (the majority of the bad are simply because they are sending too fast)! But when when you hear someone sending good morse it is music to you ears and will make you smile!

The two keys I use most often are the Kent and the Czech paddle key

So to anyone learning the fine art of Morse Code I would simply say, practise and practise and more practise. Oh and practise, once you have a basic knowledge of about 5 words per minute get on the air and force yourself to do as many QSO's as you can every day, no matter what. Honestly it's the best way to speed up and nothing to worry about, there are CW experts out there who will reply to you and most importantly go at your speed.
You will make mistakes, it doesn't matter, it happens, so what? It's your hobby, enjoy it and just continue on.

Recently an old timer I know with 40 years CW experience said to me "when starting out, if you do 3 to 5 QSO's every day for a minimum of 1 month I guarantee you will be at around 12 wpm by the end that month and wandering what all the fuss was about"! Do you know I think he's right, (I didn't and it cost me 6 months of hard work!)
And one more thing.............Practise!

Further Fun with Antennas - Part 2

So now I had three antennas the W3DZZ, the Mystery and the Carolina all working reasonably well but unfortunately my garden had taken on the look of a large antenna farm with wires criss crossing all over the place and members of my family were none too pleased. I must admit looking at all these wires did make me think that there must be an easier way.

Back when I first started amateur radio the best antenna I ever owned was the Cobwebb, a five band omni directional dipole which at 8’ square could fit in a small sized garden with little trouble, a simple compact layout that worked extremely well. But I had made a promise not to buy another commercially made antenna and in any case the price of £300 was out of the question.

However the thought did cross my mind that now I had some experience I could possibly have a go or at least an attempt at building one and I reasoned that other hams must have tried and succeeded. 

Once more I trawled through the internet and found a number of hams who had successfully built their own Cobwebs. Reading up on their experiences and by coming across the detailed plans of the original Cobwebb I thought it was worth a go.

The next day after making the decision to build I promptly went down to Maplins to buy the necessary kit, I ended up spending approximately £45 mostly on speaker cable and the junction box together with the connection wires. 

Within 3 days I had completed the connection box and by a stroke of luck also found an Australian ham on “YouTube” who had recently completed the antenna, (any potential builders out there it's well worth a view). Through following his video and reading the design plans it all seemed to come together pretty smoothly. My only problem was finding fibreglass poles to support the speaker wire and in the end I popped down to my local hardware store and located some lightweight wooden poles and after a good soaking in wood treatment they seemed to be fine for the job.

Overall the Cobweb took me ten days to build but I was pleasantly surprised by the outcome. The antenna looked just like an original and seemed to weigh about the same. I mounted it on a 5ft pole to do some testing, fearing the worst that it would be a nightmare to trim, it was by all accounts one of the easiest parts of the job. The Cobweb is now mounted 35’ on my aluminium scaffold pole that has been moved so that it is attached against one of the walls to my house.

The finished product

The Windom and the W3DZZ have been taken down and stored away. The Mystery antenna is still up in my silver birch as an inverted vee and this covers the 80 and 40m bands when required. 

Since progressing with my CW I have also built a simple 30 meter inverted vee as I have found that neither the cobweb nor the Mystery covers that band particularly well but otherwise everything now seems to work fine. I  have now had good contacts from the US and Australia (atmospheric conditions permitting). 

The Cobweb is slightly above house height but no one has complained except for one neighbour who asked me what sort of TV reception did I get with that?
The next plan is to build myself a tilt over mast so that i don't try to break my back everytime I want to do adjustments, watch this space!

The Beginning

First licensed back in 1996 I‘ve always had a fascination with communications, I think it really kicked off back in the late 70s and early 80s when I was in the RAF, I managed to get in to the communications side of the RAF Regiment squadron I was serving in and it snowballed from there.

In 1979 I served for 6 months in Belize and one of my jobs was to set up comms with our main depot at RAF Bruggen back in Germany. This is where I first learnt about the art of atmospheric conditions, antenna designs and the intricacies of setting up a radio station. From then on I always had some kind of interest in radio first becoming a shortwave listener and then finally buckling down to take my Amateur radio exams. Once qualified (M0AUW) I managed to pass the 12 word a minute morse test and by the end of 96 had my first real amateur station up and running.

My main interests are building antennas and CW, with antennas it’s not so much theory or design, but getting my hands dirty. With CW it’s simply because at first I found it so much of a struggle to learn  but gradually rather like listening to a piece of music for the first time that you don’t really like, it slowly begins to grow on you and eventually you can’t get enough of it.

Some of my friends think that Amateur radio is a dark art full of strange people and others are actually fascinated by it, particularly with morse code, most believing it went out back in the 80s. However, it’s always a conversational opener especially when I have visitors; the first thing they notice as they arrive at my house is a whopping great antenna 40 feet up in the air!