Re: Antenna switcher and splitter
The two transformer ones work better. Transformer 1 is 10 turn autotransformer tapped at turn 7. This transforms 50 Ohms to 25 Ohms. (Or 75 to 37.5). The second transformer is 14 turns center tapped.toggle quoted message Show quoted text
The 25 (37.5) Ohm tap from the first transformer goes to the center tap. The two ports are the outer ends of the second transformer.
Place a 100 Ohm (for 50 Ohm system) or 150 for 75 Ohm system across these two outer ends. This provides the isolation between these two ports.
There is only one ground connection - to the cold side of the first transformer.
Isolation and high frequency response can be improved by cancelling out the self inductance of the transformers by placing a capacitor from the center taps to ground.
For BN-73-202 ferrite cores, I arrived at 330 pF for this capacitor experimentally. See
The splitter I described is like fig. 4.
On Oct 7, 2021, at 5:48 PM, LA2PJ - Egil <egil@...> wrote: