In this video I get the transmitter on the air and test the output in the lab and hear the output using a PA based websdr.org endpoint.

Part 1 -    • ESP32 Based SDR Transmitter - Part 1 ...  
Part 2 -    • ESP32 Based SDR Transmitter - Part 2 ...  
Part 3 -    • ESP32 Based SDR Transmitter - Part 3 ...  

LPF board
https://github.com/thaaraak/lpf

RF Tools Filter designer
https://rf-tools.com/lc-filter/

The ltspice file I was using
https://github.com/thaaraak/ltspice/b...

0:00 Intro
0:59 Designing the filters using rf-tools
2:45 Looking at the lowpass filter in ltspice
4:29 Looking at filter input impedance
6:13 Looking at the filter on the spectrum analyzer
7:34 Looking at a 14 MHz bandpass filter in ltspice
9:07 14 MHz BPF on spectrum analyzer
9:51 A bit of a diversion into toroid winding and the effects...
13:28 Testing setup
15:10 Single tone on oscilloscope
16:05 Two tone test
16:57 Single tone on spectrum analyzer
18:28 Two tone on spectrum analyzer
20:04 Changed to 7 Mhz - confirming that LPF is removing harmonics
21:21 Finally transmitting. Results received by K3FEF websdr endpoint
22:39 Wrap up and next steps