The DX-88 is a very good vertical antenna by Hy-Gain, which covers the 80, 40, 30, 20, 17, 15, 12 and 10 meter bands. With an optional kit the DX-88 can also work on 160 meters. The antenna is self supporting and comes with stainless steel hardware making it quite robust in windy conditions. Like any other vertical antenna, the DX-88 performs best with a ground radial system.
When I got up this morning I turned on the FT-817 with the Miracle Whip mounted on its back. There were a lot of strong stations calling CQ TEST. I didn’t quite know what kind of contest it was but a quick check on the net revealed that it was nothing less than CQ WW DX 2005.
The MP-1 is a small, light-weight vertical antenna intended for portable use. The antenna consists of a base rod, a tuning coil and a telescopic whip. The coil is used for band change, while the telescopic whip can be used to fine tune the SWR on the desired frequency.
I took a long weekend from 28. Oct to 1. Nov. The plan was to drive from Paris to Denmark by car and take some of my stuff home as part of my moving back to DK. I left Les Mureaux on the 28. around 1000 local time and I actually arrived in JO45 after 14 hours. Not bad on a friday.
By studying the graphs in the User Manual I have come to the following parameters, which are supposed to be good enough for CW work. Note that 80 and 40 meters can not be tuned independently, which is why the centre frequency on 80 meters is set to 3.6 MHz.
The resonnance frequency of the ATX-1080 is adjusted by selecting the correct taps to connect (band change) and adjusting the telescope length for fine tuning on the given frequency. The radial length should have different lengths for each band as well. The original document describes which taps need to be connected and how long the telescope should be on each band, but says only that the radial length should be less than 1/4 lambda. Wimo, on the other hand, provides to pages of documentation in German, where they also give some start lengths for the radials. Also, a useful formula l [m] = 54 / f [MHz] is provided.
The ATX-1080 is a small multi band vertical antenna covering 80 – 6 meters, including the WARC bands. It is very similar to the MP-1, a major difference being that the coil is placed at the bottom. Also, the MP-1 has a continuous tuning on the coil while the ATX-1080 has fixed taps for the connections. I bought the antenna at the German Wimo who even supplies some extra documentation along with the original paper.
I felt I should give the FT-817 a fair chance, so I have put the DX-88 up again. Of course, I have new tuning parameters and it seemed, that some of the parameters were not like they should have been.
During my indoor tests of the ATX-1080 tonight I tried to switch to 80 meters.
I am trying again on 40 meters with the ATX indoors. It seems to make a big difference whether the radial is just thrown down on the floor or it is deployed to its full length. In the latter case SWR comes down to 1.1 or “1 bar” on the FT-817, which is somehow better than what I had outside, while in the first case I just couldn’t get the SWR below “4 bars”.