W6PQL
The amplifier BLF188XR A is a push-pull design, using a dual-LDMOS device; by nature,
this type of amplifier does a good job of suppressing even harmonics,
but the odd harmonics are monsters,
so be sure to use a good low pass filter.
Just look at this spectrum analyzer display of the unfiltered output on 40 meters:
http://obrazki.elektroda.pl/9354175900_1435522049.gif
After passing through the LPF, the spectrum is much more reasonable, and in compliance with FCC regs.
http://obrazki.elektroda.pl/9254083500_1435522411.gif
The amplifier BLF188XR A is a push-pull design, using a dual-LDMOS device; by nature,
this type of amplifier does a good job of suppressing even harmonics,
but the odd harmonics are monsters,
so be sure to use a good low pass filter.
Just look at this spectrum analyzer display of the unfiltered output on 40 meters:
http://obrazki.elektroda.pl/9354175900_1435522049.gif
After passing through the LPF, the spectrum is much more reasonable, and in compliance with FCC regs.
http://obrazki.elektroda.pl/9254083500_1435522411.gif