I have various antennas here. My two tilt-over masts have been in position for many years and overall they have given good service.
The key thing for me is safety - they need to be strongly mounted and easy to work on. No ladders. Ideally they should be extendable masts meaning that they do not need to be on the skyline for any longer than necessary, with the added benefit that I can lower them out the strong winds we get here. I need to be able to tilt them to work safely.
While my antennas need to have enough elements to serve their purpose, I also need them to be reasonable size. I do not want them to be eyesores, and if they are too big they will suffer in our winds. They cannot be too heavy and over-stress the rotator, nor need excessive bracing. Everything needs to be made of materials which can resist the salt-laden atmosphere created by the nearby North Sea. Above the rotators I use thick wall 50mm diameter aluminium poles to support the yagis, and this also limits the overall size of the antennas.
Finally, I need to strike a balance in relation to the OFCOM regulations for radio amateurs in the UK. To manage enough output power yet stick to the rules needs a bit of thought about mast location. That thinking required me to have two supports as my first one would have been in the wrong place for my current 144 and 432MHz set-up. The OFCOM guidance suggests that if there is an issue with meeting the rules then just raise the antenna - great advice but not practical here. Thus it turns out that my 2m/70cm antenna has to be in the location now occupied by my second mast.
Fortunately it is easy for me to meet the regulations on 70MHz and 1296MHz using my initial mast so it remains in use for those bands. My 50MHz antenna does not fit on the original mast so it goes on the later one. Thus: two extendable and tiltable mast supports. It would be great to have everything on one, but then four antennas on that would become a bit of a nightmare.
The current pattern was not planned but emerged over the years.
The Tennamast
My original 7.6m Tennamast arrived in 2008, 16 years ago at the time of writing. I quickly adapted it with worm gear winches. This means that both tilting and raising are very stable with no ratchets. I raise, lower and tilt the Tenna mast using a battery powered drill. Over the years all that has been needed is occasional greasing plus one set of lifting cables - more on the cable here.
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| Tennamast at GM4FVM with 36el 23cm and 5el 70MHz, 28MHz vertical alongside |
Unfortunately although this location is great for any antenna at 70MHz and above, the longer elements of a 50MHz antenna would get caught in a building when the mast is tilted over. I had not factored this in when locating the Tennamast. While a 50MHz HB9CV type antenna would just fit, it needs to be side on when tilted, and then the longer booms of the 4m and 23cm antennas would hit the building instead. I bodged about for a while and then decided that the only answer for 6m was to locate that antenna further along the house on the gable end of our kitchen extension.
The CUG mast
The first antenna on the gable end was in 2011. I was quick to locate my 6m HB9CV there. Initially I used ladders to reach a set of T and K brackets fixed to the wall. Access got difficult as time went on and I bought a cheap scaffolding tower to make life easier. Despite this there were two "incidents" when I ended up in an uncontrolled descent and plummeted to the ground. In the end it was clear that I needed another tilt-over mast on the extension gable end to ensure safe access.
My CUG mast arrived in 2016, 8 years ago at the time of writing. On it went my 5el 6m PowAbeam and my 2m/70cm antennas.
The 10m aluminium CUG mast was installed by Gary and featured hand cranked winches. It pretty quickly proved to be too weak for the job in hand. As I have mentioned here before, it can get very windy on the East Coast of Scotland. The aluminium mast was simply too light for the stresses it was put under and I knew immediately that this was not my greatest decision. The choice had been made on the basis that an aluminium mast was about 20% cheaper than the steel equivalent. The Tennamst was steel and caused no problem, but I failed to learn that lesson. Aluminium might be a risk but it would probably be OK, or so I thought. That decision might have been a good one if I lived in an inland valley, whereas being not far inland from tall sea cliffs it proved to be not so good. Not that the aluminium mast would fail or anything, it just whipped and twisted about in the gusty winds. Maybe I had underestimated the wind loading of my antennas too.
I have learned over the years that if I make a mistake it is best to accept that and fix it. I contacted Gary and he offered me a part-exchange to trade up to a steel mast, the one I now have...
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| The steel CUG mast at GM4FVM, with DUAL 2m/70cm and 5el DUAL yagis and 4m vertical alongside |
Changing over to the steel mast made a huge difference. The second mast is very stable in strong winds.
The steel mast came with a rotator cage, something which takes the strain off the rotator and reduces the possibility of rotator failure in strong winds. The inclusion of a rotator cage required me to purchase a Yaesu bearing which is fitted to the top of the cage, allowing the top pole to rotate.The winch is fairly noisy and I may have to come up with another winch solution similar to the one I used for the Tennamast.
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| Steel CUG mast at GM4FVM tilted over for some work on the preamplifiers |
The steel mast is a three section version, whereas the aluminium one was just two section. When delivered the upper steel section kept sticking in the raised position leaving the mast unable to be lowered. Luckily GM3PPE came to the rescue with his large set of files, and some rogue galvanisation was filed off the upper box section. The three section mast now works well, but it possibly adds some scope for inaccuracy with antenna azimuth settings due to the extra slack in the two joints. This hardly matters in most cases, but maybe on 70cm moonbounce it might cause some problems.
While I had a issue early on with two broken pulleys on the original CUG mast, the second one has not caused any other problems once the sticking top section was filed down. Just because steel is heavier than aluminium the process of winching the mast over is now a heavy job.
I transferred the antennas from the aluminium mast to the new steel one. At the time these were, a 9el 144MHz and 16el 432MHz DUAL yagi fed separately by two runs of coax, and the 5el 50MHz PowAbeam. After giving eight years good service I recently replaced the PowAbeam with a 5el 50MHz DUAL. I stayed with five elements in order to keep the visual impact low but also to stay with a rigid boom and good wind resistance. While the steel mast could certainly take longer and heavier antennas, I do not want to go beyond self supporting ones into the world of bracing.
Winches
The Tennamast came with 600lb aluminium winches with ratchets which I replaced with worm gear ones, 1200lb for lifting and 1500lb for tilting. You can read about this here and see photos of the winches. One benefit of using a battery powered drill for lifting and lowering is that as I have three batteries for the drill I am unlikely to get stuck with a flat battery.
The first CUG mast used hand cranked winches which can be hard work. When it came to specifying a successor I opted for an electric winch. It is powered by a 12V lawnmower battery stored in a weatherproof "Dri-box" alongside. The battery can be charged in situ using a weatherproof mains socket nearby, or if it is raining or snowing I can carry the Dri-box into the garage and charge it there. It has to be charged every month or so, depending on use.
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| Noisy Rhino lifting winch at GM4FVM, with hand winch for tilting seen behind |
The winch came with two remote controls and a wired rocker switch. The connections to the wired switch seemed a bit light for outdoor use so I took that off and simply use the remote controls. I only use them standing beside the winch, but even then the signal seems weak and sometimes is interrupted. The winch seems to handle the load easily.
I fitted a fuse to the battery and used Knightsbridge weatherproof connectors to allow the battery to be removed from the winch circuit and charged. I then fitted a second Knightsbridge connector to a dedicated "smart fast charger". The charger can be used outdoors but it is not weatherproof, hence the need to charge the battery in the garage at times. A basic charge to 90% capacity takes 20 minutes, but for a full charge from empty can take about 40 minutes.
The Dri-box is intended for mains wiring for things like outdoor lighting. Here it only has a 12V battery inside and it seems to have remained watertight. I used heavy outdoor cable to connect to the winch as the current carried for short periods is quite high.
In conclusion
I certainly never set out to have two masts. However I am satisfied with how the present system works. It is surprising how often the two rotators are pointing in different directions. The load on each is reduced and so is the visual impact. Very rarely are both masts raised at the same time. Most of the time both masts are lowered - I would say that one of them is raised in daylight once per week or less. I am not so concerned about antenna height, it is the ability to tilt them for safe work which is most important for me.
The whole set-up meets the OFCOM rules. The masts have been up here for 8 and 16 years respectively with only minimal maintenance being required. Any maintenance which is needed can be done safely from ground level. Overall I would say I am content with the way the masts perform and I would recommend either of them to anybody who was considering something similar.
73 Jim
GM4FVM
