My Pixie produces about 500 mW of output power when driven by a 13.8 volt supply. The total input power to the board is about 1.5 watts. As I’ve mentioned the Pixie only suppresses the 2nd harmonic by about 10 dB with it’s internal filter.
Pixie running at 13.8 volts, producing 500 mW output, with second harmonic down 9.5 dB from carrier
When I added the 5-pole filter that I described in my last post to the Pixie minus one turn on each coil, so 19 turns each (keeping the original filter in place), the output power was reduced to 250 mW, but the 2nd harmonic reduction was improved to -40.7 dBc; almost passing!
Pixie running at 13.8 volts, with 5-pole filter on output, producing 250 mW output, with second harmonic down 40.7 dB from carrier; just 2.3 dB above FCC limit
Recall that other Pixies I have tested have 2nd harmonic suppression of about 20 dB. That will probably allow the additional filter to meet FCC requirements.
I also removed another turn off of each inductor, but only observed a slight improvement in output power (it went up to 280 mW). The 2nd harmonic suppression was negatively impacted as well, now only 37.5 dB below the carrier.
