I've had quite a bit on lately finishing the Iceni and Anglian transverters by G4DDK but I managed to find some time to do a bit more to the 70cm PA.
Using the same setup as the last time I tested the harmonic output I got the following results.
2nd Harmonic was at -38dBc originally measured at -40dBc
and the
3rd Harmonic was at -68dBc originally measured at -53dBc
So not the big improvement I was hoping for and in fact 2dB worse for the second harmonic.
I tried running the unit with a lower drive giving an output of 50W and in fact the 2nd harmonic got worse as well as at various other lower drive levels.
I've yet to decide how to rectify that small problem I could use a small mini-kits LPF from Australia or the cheap way a 1/4 wave stub notch filter cut for the 2nd harmonic.
The other thing I've discovered is to not pick the PA up after running a CW test as the heatsink gets mighty hot. ;-)
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