On Thu, Feb 23, 2012 at 12:56 AM, mbramwel2001 <mark-yahoo@...> wrote:

> You can raise the VHF to 220 or lower UHF to 220mhz.
>
> Based on signal reports this weekend, I gave a better signal on UHF-low
instead of VHF-high.

Makes sense.

Given that the VHF TX chain has a VHF low pass filter and that the UHF
TX chain has a UHF low pass filter ... if you go to 220 MHz (please,
please, please capital M, capital H, small z) in VHF-high the LPF is
eating up your RF (and harmonics).
If you transmit on 220 MHz on UHF lowered then you're well below the
LPF cutoff which is probably somewhere at 500 MHz ... therefore your
even harmonic on 440 is passing untouched...

These effects of the LPF sum up with the RF PA characteristics, which
might be more efficient if run 440-to-220 rather than 150-to-220.

Greetings,
Paolo ZYW