Reflections about a remote mediumwave listeners station

 

Almost a year has passed since I was able to put the theoretical description of raising the mast into practice. http://dxerscorner.tikishop.de/archives/170-Aldi-Supermarket-antenna-mast-how-useful-is-it.html

The conclusion: the flagpole segments of the discounter are excellently suited to erect a pole with a height of 10 m quickly. A little preparation time is necessary.

First, the discs for the guy lines were sawn and drilled. I chose sturdy round plastic covers with a diameter of about 15 cm as the material. The length of the guy lines could not be determined in advance. They were laid out so that they could be extended at any time. A total of three guy lines are attached to the mast. The plastic covers were attached to the somewhat narrower connecting pieces on the mast segment. The diameter of these connecting pieces fits exactly for commercially available hole saws. The base of a swivel office chair was used as the foundation for the mast. This also fitted perfectly and coincidentally exactly into the lower mast segment. For additional security, the lower section was weighted down with washed concrete slabs. The guy lines (UV-resistant, tear-proof material from DX-Wire) were attached to nearby fruit trees with ring insulators.

Mast structure: The mast top consists of a round black plastic element with a U-shaped feed-through. The antenna wire is fed through here first. I use 1,6 mm galvanised woven wire. This is on a large 1000 m roll, which has been attached to a small garden trolley so that it can be unrolled. The wire can be threaded through the top of the mast without any problems and can be pulled on even at great heights.

I started with 3 mast segments inserted into each other and gradually worked them upwards. At some point you reach a point where the mast is no longer secure without guy lines. Therefore, the guy lines were then lashed tight, the mast aligned plumb and then the lines loosened by about a metre to insert another segment.

After 8 m a critical point is reached. Here you have to make sure that there is hardly any wind, you also have to be able to lift the mast plumb upwards with your hands and have a helper place another segment at the base and connect it. This procedure is repeated until all mast segments have been inserted. Since the guy ropes are loosened by 1 metre at a time, the mast can practically never sway more than 1 metre and is protected from swaying by exactly this metre. This tolerance meter has never been used by me or by the mast.

Connecting to a new mast element takes no more than 1 minute. I used 2 flagpoles to get to a height of 10 metres. Practically, another metre would also be possible, but I did without. The higher you go, the more wobbly the top can become. At the end of the construction you have to be able to lift 9 m and hold it plumb. That was enough for me, and the experiment succeeded. If someone manages to work in the 11th metre, I would be pleased to hear from you.

This mast replaces the old mast of the DDA, which is only 4.50 m high. As this antenna shape still requires a second mast top - it has a height of 9 m at the moment - I will also replace this mast with a higher one when the opportunity arises. At the moment, however, the flagpoles of the discounter are not available.

The new K9AY with extended circumference has a height of 9.50 m, the single wire a total length of 26 m, which corresponds to a limb of 8 m or 5 m. No problem was the erection of the mast. Most of the work fell as wires had to be entangled and the almost ailing tree crown was felled. A first hearing test showed that it is not worse than v1.0. The freestanding position without disturbing tree crowns, better copper lines, improved grounding and other dimensions provided a more rounded sound picture. Better separation accuracy and better forward / reverse ratio are the decisive factors in my assessment.

The masthead of the tree on which the two antenna wires of the K9AY crossed broke at one of the last storms. The reconstruction is now done with stable material and even better antenna wires. The felled tree will also serve as a "scaffold". It is sheathed over a length of 4 m with a 75 mm HT pipe (plastic water pipe) and is thereby brought to a total height of 9,50 m. It replaces the original height of 7.50 m. This results in other lengths, namely longer wire lengths.

The 1mm green coated garden wire is connected to a classic beverage antenna matching set with 50 Ohms from / lowbandsystems.com /. It is a directional antenna which should be good on NA stations. First tests shows it's good working - also in the opposit direction East Africa - and some dB improvement compared to the K9AY switched into a NW-direction.

Welcome back to the blog!

Up from now there will be regular writing intervals again on the built-up of my remote garden station.

I used the HAM Radio Friedrichshafen to complete some gear which was missing. At the moment a couple of items wait for use in the station. A few changes in the antenna construction have been set due to mount problems.