Diamond W-8010 5-band antenna
Many radio amateurs do not have the space to implement full-size antennas. Compromises are needed in a smaller space. It is possible to implement a 10/15m turn signal, but since the bands are mostly closed and the allocated frequency segments did not appeal to me, I was looking for an antenna mainly for the lower bands.
Jirka OK5IM offers mulitband KV vertical with a radiator height of 13m. The problem with vertical antennas is the radial system. I didn't want to dig up the garden and the raised radios would have to be very close to the telephone wires and they wouldn't fit in the garden at all. Nevertheless, this antenna can be very interesting, see. http://ok5im.com
Setting up shortened antennas requires experience, time and measurement technique. Measuring the distance between the skylight and the tree showed only a distance of 21 m. What about this space? A single-band inverted L antenna was offered, which, however, would require burying several radials. Out of "laziness" I started looking for a horizontal antenna on the Internet. Surprisingly, there are not many constructions. During one such search I found an antenna Diamond W-8010, which is sold in Slovakia by AWAS, see. http://www.awas.sk . And it was decided.
The antenna is designed for five bands: 10m, 15m, 20m, 40m a 80m. It uses two emitters with traps with a common power supply through a balun. Its length is approx. 19m, weight 2.5 kg. The load capacity is 1.2 kW. It is necessary to have two points at the required height, at least 20m apart, and another two points lower on the inclined radiator.
The upper emitter is for bands 80m, 40m a 15m, lower, skewed for 20m and 10m bands. Tuning is done at the working height from the shortest band to the longest by shortening the wire stubs at the traps. The advantage is, that the tuning of individual bands is not affected in this way.
The antenna is supplied in a thick double-gelite box, which contains everything you need. Is possible, that you will need more nylon cord (for hanging the antenna) and a few more zip ties. The problem was the manual, which was only in Japanese. Fortunately, an English version of the manual is available online.
After pulling the antenna to the working height, fine-tuning is necessary. In the manual, you will find how big a frequency change will be caused by shortening the stump by 1 cm on the given band. The team, that all stubs are full length after antenna installation, the antenna will resonate below the bands. In my case, there was a resonant frequency on 10m 27,45 MHz and other bands were very low.
Bandwidth for PSV up to 1,5 is: na 10m 500kHz, na 15m 400kHz, na 20m 100kHz, on 40m 60kHz and 80m 24kHz (according to the manual). Apparently, the loss of the coaxial cable is the bandwidth of 80m to 45kHz (according to PSV metro MFJ and TCVR). However, it is possible, that the bandwidth is also influenced by the environment in which the antenna is installed.
Tuning requires patience and having a thoughtful way of lowering and raising the antenna. I had to hang the pulley on the tree (birch tree) mountaineer, because climbing a birch tree without branches is nothing for radio amateurs, HI. Tuning took about three hours of pure time, since after shortening the radiator it was necessary to pull the antenna back, go to the station, measure PSV and start the antenna again. As I tuned the antenna to SSB segments, at 80m it was not enough to shorten the stump, it was necessary to move the end insulator by 15 cm, to make the antenna shorter.
The most important thing is of course, whether the antenna is working or not. And this is the area, where the Diamond W-8010 shines. Nevertheless, that I was primarily concerned about the 80m band, the antenna works well at short and DX distances. She won the OM Activity contest, Plzeňský poháe and a few EU DX on 80m. Unfortunately, Nevertheless, that I heard several JA stations, I didn't have a chance to call them. He listens well on higher bands, however, class N segments are empty, so I haven't been able to properly test it on DX yet. It's gratifying, that I didn't register TVI with me either, not even with the neighbors (power 100W). The antenna is almost invisible to passers-by.
The negative plasticity of the antenna is, that it is sensitive to rain and snow, which cause a shift in the resonance frequency (approx. 1 – 1,5% downwards).
Diamond W-8010 was a pleasant surprise, the antenna works very well and helped solve the difficult issue of fitting the antenna into a small space.
