Tom W8JI wrote:
>Let's not leap to conclusions! The answer is actually no. Most
>amplifiers will meet the regulations easily without a pi-L, and many
>pi-L's actually are insignificantly better on harmonics or no better at
There are some interesting measurements on G4AXX's website, at:
For that particular amplifier, the harmonic levels on various bands
ranged from -45dBc to undetectable. Mark found that the unexpectedly
good results were due to VHF parallel resonances in the shorted turns of
the tank coil, which sometimes - though purely by luck - could notch out
the harmonics. Scroll to the bottom of the web page for details.
(Also check out the rest of Mark's site, which is full of high-quality
Agreed that the harmonic levels into real-life antennas would be
different again, and even harder to predict... but the regulatory tests
into 50 ohms.
73 from Ian GM3SEK
Amps mailing list