[TowerTalk] Narrow Band Filters

[Tom Rauch]

> A phasing unit like the MFJ will work and have plenty of
dynamic range,
> but it would require a bit of work to get it setup and
adjusted. It might be
> practical for a really serious Field Day effort, but my
guess is that you
> would need one guy who did nothing else but handle the
phasing unit
> design, installation, troublshooting, and adjustment. Our
Field Day usually
> doesn't have enough workforce to make that practical.

The MFJ unit has totally inadequate dynamic range for this
application, and it is the best of all the units I have
tested.

The idea of an HF filter for in-band rejection of different
modes is useless, unless very expensive. Even helical
resonators would have inadequate Q.

Even on 160 meters deep rejection at 40kHz requires very
good components. I had to use multiple Q~500 inductors in my
BPBR filters on 160.

73 Tom