Elsie

Here is the schematic for a standard 50Ω LPF for the 12-11-10m bands. PCB Render: Actual photo: NanoVNA results of the PCB build: Build Notes: These values come from RobG (https://hackaday.io/) Shunt C: 100pF Series L: 12T on T37-6 core, 11T on T50-6, making about 485nH Shunt C: 180pF Series L: 13T on T37-6 core, 12T on T50-6, making about 580nH Shunt C: 180pF Series L: 12T on T37-6 core, 11T on T50-6, making about 485nH Shunt C: 100pF Winding wire size: 27 SWG (is non-critical) Note: We needed to reduce 1T (from the values specified above) when using the T50-6 cores. As usual, use a DE-5000 LCR Meter (or better) to know the exact values. ...

Some weeks back, we published our designs for building reproducible TX-BPF filters easily. 10m TX-BPF: Results of the Dhiru's Manhattan build: Results of the PCB build: While many amateur radio operators focus solely on antenna optimization, the significant benefits of TX-BPF filters are often overlooked or under-discussed in the hobby! Even with HOA antenna restrictions, you can still optimize your station's performance through proper TX-BPF filtering. ...