Re: Topband: INV L matching
On 5/14/2020 9:26 AM, Tom | SP5XO wrote: d, wideband match. Since short vertical inv L over reasonable ground should have roughly 20 OHm impedance that could work here as well. The matching network that will maximize bandwidth is an autotransformer wound on a 2.4 inch diameter ferrite core. For example, a transformer with a 3:2 turns ratio will transform 50 ohms to 22.2 ohms. I use a homebrew autotransformer on my 90 foot vertical which has around 25 ohms drive impedance. See Jerry Sevick's book on RF transformers for info on "un-uns". Rick N6RK _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: INV L matching
Hello OMs Topbbanders As I'm planning to put up inverted L antenna for next season i will face the matching vs bandwidth struggle I know there is a cure for short vertical section and low impedance (with reasonable radial system) and I already tested some extended horizontal section and matching capacitor in the feeedpoint However i was considering some other impedance matching methods and came across DK7ZB matching transformers. For example to get good match for 28Ohm yagi there is 1/4 wave 75Ohm parallel feedlines transformer used with good, wideband match. Since short vertical inv L over reasonable ground should have roughly 20 OHm impedance that could work here as well. Sure it is 2 x quarter wave 75 OHM coax (shortened by VF) but is there any wideband "gain" for such feeding method? It would be still easier than switching remotely some caps each 10kHz or something. Is there anybody who tried this one? Thanks Tom sp5xo _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
