Hamming Fun

Category: My Antennas

  • Mobile Antennas

    Antennas
    Antennas
    Recently had a nice chat with somebody about my experiences with mobile antennas and here is what I said in my e-mail:
    What radio are you using? I used to have a Yaesu FT-707 that I pulled out of the mothballs but the VFO wasn’t stable enough any more. Then I bought a second hand FT-747 which I’m extremely happy with and I will probably keep it for home use. Then recently I bought a Yaesu FT-857D from OM Sam Maree in Cape Town and I’m also happy with it except for a few niggling things. The FT-857D is an excellent mobile rig, and the combination of the FT-857D plus the FC-40 automatic tuner is a killer combo. You have NO idea how well they work together until you actually use them. Awesome stuff.

    The FC-40 tuner will tune just about any random length of wire to the transmitter and was built specifically for that purpose. When I go mobile I just use a kettie to shoot a thin piece of fishing line into a tree and I go. My wire length is usually 10 meters or so of thin copper wire. You should try that tuner out sometime.

    I also tried a vertical without traps but I get variable results, and I was going to try a vertical with traps next. My experience with home based stuff is that verticals are a last resort, except if you can get a good early model bandspanner or similar. The good verticals tend to be monobanders too, unless you put your hand deep into your pocket for a screwdriver. By which time I’ve lost interest.

    My best antenna, by sheer luck, and by far, turned out to be a G5RV. I eventually purchased a “G5RV Junior” from Sam (Radio Accessories in Woodmead) which has become my reference against which I check all my other experiments. I’ve done dipoles with and without traps, a “Terminated Folded Dipole” from Buxcomm, end-fed wires, the lot. Each has some advantage and some disadvantage. The disadvantage of the G5RV, in spite of its excellent usability, is that you have to use it with a tuner as the impedance varies a bit. I actually don’t mind this, as I bought a second-hand Yaesu FC-757 ATU which is semi-automatic but works very well. I have never felt that I lost a signal because of the tuner – but the purists will argue till dawn. You can actually make a lightweight inverted-V G5RV that works extremely well with simple wires, if you can find pink 300 ohm TV wire. If I can find a few meters I will pay with solid gold. It outperforms any dipole under similar conditions, and I think it has to do with the feedline matching.

    I also have an old Army wire antenna complete with traps and balun for 80/40/20 which makes an easy V for field days but I don’t seem to use it a lot nowadays. I don’t have the vertical pole though … pity!

    I must admit my biggest problem – for mobile use – has always been power. Dragging a 12v/20A supply around is just a pain in the back. By the time you’ve dragged your power supply out from the boot of your car to where you put your antenna, it becomes attractive to rather pull your car up to where the antenna is. In that case, even a well-tuned vertical monobander sounds good. I know I’m lazy … but the radio also gets bumps and scratches when you haul it in and out, so a somewhat fixed installation feeding directly from the car battery with short leads (less fading on high power signals) is a very good compromise.

    Well, thats my opinion for the day. Have fun whatever you do and please keep in touch – I would like to make a contact on the air sometime. Chat soon.

    73s

  • MFJ G5RV Junior

    G5RV Junior
    G5RV Junior
    As you might have gathered by now, I restarted my ham hobby after being absent for many years. The absence also meant that my antennas were either bent out of shape, or missing some critical parts.

    Panic stricken I rushed off to my local purveyor, Sam Ford ZS6___ of Radio Accesories in Woodmead waving my credit card at anything that looks like it could receive radio waves. After calming my nerves, Sam pointed out that he has a MFJ-1778M in stock. What? I asked. So he says: Single dipole, multi-band, no traps. OK, he has my attention.

    It turns out to be the best advice ever. The MFJ-1778M JUNIOR G5RV is supposed to tune up on 10-40MHz, can handle 1500 watts (OK, I only have 100 watt at the moment), and is just under 16 meters wide. Now thats impressive, and will fit my chimney mounting strategy. It took me a full hour to hoist this lovely piece of equipment onto my tower AND make a 15 meter RG58 cable, and before tea time on Saturday I keyed up the tuner.

    Initially I was very disappointed, it tuned up on 40m and 10m but not on 20m. Reception was very good, although remember I am in a noisy environment. Then the following weekend and after discussing with Sam again, I decided to lower the antenna and create more of a “Cloud Warmer”. Initially I came down a meter, but after some more experiments I ended up with a nearly horizontal antenna no more than 3 meters above ground level. It may be a cloud warmer but it tunes up instantly on any band between 40m and 10m (including the WARCs) and so far it has become my all-time favourite antenna. It is the standard against which I judge all my other experiments.

  • The Chimney

    The Chimney
    The Chimney
    You know, sometimes when you write a story, an inanimate object takes on a personality of its own and becomes an important part of the story. And in my story of my ham radios, the chimney is becoming an integral part of the story. It is holding up its side, pun intended.

    This house was built in the 1970’s when fireplaces were commonplace. The fireplace commanded a place of prominence in the lounge previously, but it hasn’t been used for 20 years. Until I spotted that it was holding up a sturdy 5 meter 50mm thick-walled antenna pipe with an old TV and FM antenna mounted onto it. The chimney was also in the middle (more or less) of the stand, and the furthest away from all the trees. It was also not very far from the spare bedroom which was going to do double duty as my shack.

    And so, with the addition of a 1m height extension (half a pool cleaning pipe) and a few pulleys, I had myself a perfect antenna tower. The ground slopes quite a lot, but at that point it is able to raise a wire antenna (inverted V) about 12 meters above ground level. It is not too hard to get to it, and the brick portion also holds my DSTV antenna and my weather station wind vane. All in all the best possible location I could wish for. I will add some diagrams and measurements later, but in the picture you can see the MFJ G5RV-Junior hanging happily from the top in inverted V format. This picture was taken from the river side looking south (and uphill), with my shack to the left of the lounge.

  • The Antenna Farm Is Growing

    Antennas From Chimney
    Antennas From Chimney
    Although the picture is very skew and not a good rendition of the antenna, I built myself a “test” version of the Balanced Termination Folded Dipole (BTFD) as shown on his website by Buck Rogers Sr K4ABT of BUXCOMM.

    Now before we carry on I need to acknowledge my friend and colleague Bruce Rodrigues who used to say: “There is nothing more permanent than a temporary fix”. This antenna might go in the same direction, I like what I hear.

    Firstly I wanted to find out for myself if the folded dipole, terminated in the middle with a 450 ohm resistor, would be more quiet and still receive low level signals. So I made a rough hand sketch of two side loops with 21 meters of wire each side. I didn’t have proper antenna wire so I used electric fence wire – lots of that around. It is a multi-strand wire, silvery-looking, and it is very stiff so it must be steel or something. I bought a 10mm dowel, cut it into 220mm pieces and drilled 2mm holes near the ends for he wire to pass through. I purchased a random 25 watt 470 ohm resistor (I have no idea if it has inductance or what) and with electric fence crimp collars wired up the works in less than an hour. I’ll post some photos later. The balun is a problem as I don’t have a 9:1 balun available, so I used my standard 4:1 balun and I’m expecting some degradation because of that. I strung it from the highest point on the chimney pole to a roof eave in a slightly E-W direction.

    The photo shows the middle area of the antenna with the resistor on top and the balun below.btfd

    Comparing it to my MFJ Junior G5RV on-air (below the BTFD in the picture) it was giving very similar signal reports, and it was about 2 S-points quieter. This is enough to do some more scientific measurements and make some refinements, like replacing the balun. Initial impressions were very favourable and I’ll keep you posted.

  • Huisbesoek: ZS6UT Ed Willers

    Ed Willers ZS6UT
    Ed Willers ZS6UT
    I had the privilege of visiting Ed Willers ZS6UT at him temporary QTH in Faerie Glen recently. It is always a privilege to meet one of your fellow hams in person, and Ed was no exception.

    The background is as follows: You will read about the noise (QRN QRM) at my QTH, and my attempts to reduce it to lesser levels. I’ve tried just about everything. I’ve been offered a “noise cancelling speaker” by OM Sam ZS6___ who runs Radio Accessories and is a good friend. I’ve put tons of ferrite beads on every wire in and around the shack. I’ve made good earths. Everything helps a little but, but nothing makes a huge improvement.

    Except the literature on Small Magnetic Loop Antennas keeps on popping up. Everybody seems to say that they are small (about the size of a bicycle wheel) but that – for their size – they perform quite well under noisy conditions. And in true ham fashion I start phoning around. Not too long and OM Hans Kappetijn ZS6KR gives me the number of Ed ZS6UT, who was keen to show me what he had done.

    So I popped in for a quick visit. Ed runs a very nice shack and while he is in a temporary QTH he hasn’t installed his magloop. Instead he depends on a multiband vertical and a 80m horizontal loop. He jokingly shows me how he used his fishing rod and a car spark plug to get some fishing line into a bluegum tree. I was surprised by how quiet the loop is in comparison to the vertical. He has a vacuum cap that he is going to use on his small magnetic loop as soon as he can put it up. Awesome item. After Ed’s advice I now know exactly what I should be looking for.

    Thanks for the hospitality Ed. We’re going to cook the bands with our loops.

  • A Nice Suburb But Not For Hams

    View from the gate
    View from the gate
    I live in a slightly older suburb in Johannesburg. I bought this property because the streets and houses are surrounded by trees and we are adjacent to a river where families walk their dogs in the afternoon. When you enter my property from the street you are greeted by green lush trees and shrubs.

    Oh, I forgot to mention one small unimportant detail: Being next to the river also means my property is at the lowest point in Johannesburg. No matter in which direction you start moving, the only way out, is UP. This is especially true for ham radio signals.

    That little dot in the middle of the photo is not a spot on your screen. It is the balun on my new antenna, a BFTD (balanced terminated folded dipole). I read about it on the Buxcomm website and tried it out. Seems ok, but more about it later.

    Sigh. Any clever suggestions, anyone?

  • On The Roof

    IMAG0194I picked up a nice sun tan on Saturday and it was unintentional.

    I just unpacked my radios after many years, I renewed my SARL membership, and I was ready to go! But … no antennas. So out of the house, survey the environment and check with the XYL about the limits of aesthetic encroachment she would tolerate. You will probably hear about this many times but I live in an old suburb, I’m surrounded by tall trees, I have an Eskom servitude on my back wall with tall power lines 40 meters away. Any signal will struggle to get in or out. Nevertheless, there is an old FM antenna bolted to the chimney and it is not being used any longer as we’re using a DSTV dish.

    In my excitement I forgot to watch the weather. It was a blistering hot day and on a freshly painted matt black tile roof Apollo the Sun-God did his best to cook me from both sides.

    Nevertheless, my faithful casual labourer Thulani stood it out with me and we pulled down the old TV antenna, extended the pole by 1m with a swimming pool pipe, and pulled up a wire antenna. This is temporary though and we will have to go back up again once Ra has depleted his wrath.

  • New Website

    Welcome to the new home of ZS6ALU, Leon Uys. I haven’t been on the air for a while. An acrimonious – read expensive – divorce took its toll. Hobbies took second and third place after my little one (you can read more about her here) for a long time, maybe 20 years. During that time I packed my radios away in bubble wrap, my desires became frosted memories, and I barely survived.

    The good news is that things are starting to stabilise on the home front. So, with some trepidation, I unpacked my FT-707 and cut a piece of wire for an antenna. On that same Saturday I got myself a suntan on the roof and a stretched muscle from tying cable ties. I claimed my corner of the world in the spare bedroom, next to the window, I wheeled in an old computer stand, laid down an extension cord for power, and checked for smoke. Hearing the crackle of static was euphoric.

    Eventually it is all coming together. This is posted in January 2013 and I will keep you updated as I start putting it all together.

    Watch this space for pictures and news.