The use of modern technologies also has a future in our amateur radio hobby. When some time ago I lost one arm of a really good broadband dipole on KV due to the administrative intervention of the municipal office, I had to solve our usual dilemma - what and where to stretch or build and how it will work.
While searching a lot of information sources, I came across a leaflet in my own ham-shack, which I accidentally picked up at a stand last year at a meeting in Holice. I almost couldn't believe my eyes when I saw a device on the flyer that should be able to adapt dipoles from 2 x 6 to 2 x 40 m to any KV band.
Device tagged SYMMETRICAL ANTENNA SYSTEM – REMOTE CONTROL UNIT – AG-3CU it promised unexpected possibilities in its description. After ordering from the relevant company, I was still thinking about some version of the dipole and ended up stretching a single-wire dipole 2 x 19.8 m. The center at about 15m on the ridge of the roof and the ends inverted at about 8m on the masts seemed quite acceptable to me.
I used balun FRITZEL 1:1 in the center of the antenna and 26m of coax to see what this configuration can do. Unfortunately, the result was not very convincing - it was at 3.5 MHz PSV 1.5 and on 10.1 MHz already PSV 2. It was even worse on the other bands.
After installing the device AG-3CU however, instead of the FRITZEL balun, things started to happen. The antenna in this configuration can be tuned to all bands from 1.8 to 28 MHz PSV 1.3 to 1.5.
Using the control unit located in the ham-shack, the antenna is tuned to the best PSV through a multi-core cable and this setting is stored in its memory. After switching the transceiver and the control unit to the appropriate band, according to the PSV of the meter, the output, remotely controlled butterfly capacitor, connected directly to the dipole conductors, is adjusted to a minimum PSV. By simply turning off the power, the output from the input balun is directly connected to the dipole. A nice detail is also the common grounding of both arms of the dipole through high-ohm resistors to the ground terminal.
This article is definitely not intended to be an advertisement for the product, also because its price is certainly not popular and is close to the price of the antenna Titan. It is also a bit annoying that the outdoor unit has a fixed control cable, while this cable is terminated with a multi-pole plug. Pulling it through different spaces for cables is therefore not easy.
However, a great attraction for the future is the possibility to build a directional antenna for all KV bands with arms made of fishing rods 2 x 6 m.
Jirka, OK1FTJ