Impedance matching - RSP1A
Posted: Sat Jan 19, 2019 3:44 am
What is everybody here doing for impedance matching between antenna and RSP1A? My antenna is nominally 300 ohms and I am using trial and error to find the optimal transformer. Feedline is 300 ohm twin lead. Antenna is a "horizontal loop" (actually in triangle shape) of 75 metre perimeter. Modelling by Phil (VK7JJ) shows these antennas are nominally 300 ohms for most of the SW spectrum.
Am making these transformers out of ferrite toroids and experimenting with the number of turns. Started with 11/27 turns (based on internet research) but have found that, with the particular ferrite material I have, 5/12 turns is giving a better signal to noise ratio.
Also, am wondering whether it would be worth making a 1:1 transformer, to be placed at the antenna for the further elimination of common-mode noise. Worth it?
Interested only in the SW spectrum.
Thanks.
Am making these transformers out of ferrite toroids and experimenting with the number of turns. Started with 11/27 turns (based on internet research) but have found that, with the particular ferrite material I have, 5/12 turns is giving a better signal to noise ratio.
Also, am wondering whether it would be worth making a 1:1 transformer, to be placed at the antenna for the further elimination of common-mode noise. Worth it?
Interested only in the SW spectrum.
Thanks.