I have finished the beverage antenna preamplifier. The 9:1 transformer is based on the W8JI’s recommodations. It is wound on the tree binocular ferrite cores BN73-202. I was wondering how the SWR is. When terminated with 450 ohms there is no significiant return power, when terminated with 470 ohms the SWR rise to 1:1,1. Perfect!

The schematic diagram of preamplifier looks very simple – two LC circuits and MMIC. There is much more to do with adjusting bandpass filter and fiting the circuit in the shielted box and all in the waterproof box.

The circuit was later improved with a LED diode which is indicating if the current is flowing to the box or not. Output plug is standard PL.

Tags: preamplifier | beverage | antenna | ferrite cores | transformer | W8JI | schematic diagram

Topband with its wavelenght 160m is not very easy band. Dimensons of antennas are extensive. For MW9W contest crew I have prepared simple but effective antenna for 160m – the Inverted L antenna. It’s based on the material DK5WL „Invisible“ DX Antenna for the Low Bands.

The Inverted L antenna is simple quaterwave antenna with a shape of inverted L letter. Most transmitted energy is vertically polarized. That’s an advantage for DX contacts.

Jirka OK5IM is selling fibreglass poles with total height 12,5m. I bought two and prove the antenna in the IARU HF Championship with impressive result. Try it too!

Tags: antenna | topband | Inverted L antenna