I inserted a 2m band pass filter and my swr went from flat to 1.7:1. While
I know that’s not very bad, I like to keep it at 1:1.
Chuck W5PR
On Mon, Apr 26, 2021 at 2:31 PM Pavel Perchine <pnihsrep@gmail.com> wrote:
> Joe,
>
>
> > 1- To have the filters provide the ultimate best rejection they can
> > provide the impedance must be as close to 50 ohms as possible.
> > Is this true? If it is, is there any published data showing how much is
> > lost on performance due to "X" SWR?
> >
>
> There is no relationship between the filter SWR and maximum filter
> attenuation but there is a tight connection between SWR and Insertion
> filter loss. You can have very good filter rejection and very bad filter
> SWR (return Loss) at the same time.
>
> >
> > 2- This one is even more important. They are rated 200 watt units. "At
> > 50 Ohms"
> > Now SWR that is NOT 50 Ohms Can make some pretty high voltages true?
> > And I am assuming these voltages are what gives each unit it's power
> > rating.
> >
> > With High SWR some filter parts inside will be under the stress and also
> the dissipation heat (with increased filter insertion loss) will go up too.
> Both factors can destroy the filter.
>
> I would keep an antenna SWR below 1:2.
> SWR =2 is not the best, it is 25 or 100 Ohms but some filters can handle it
> without any issue.
> With SWR going higher the chance to smoke your filters is very high and
> the tuner addition will help for sure.
>
> Pavel
> VA6AM
> https://va6am.com/
>
> Go too high and fry a cap.
> >
> > Now Our Station, (The only CW station) will be running a K3 with the
> > Roofing filters. My Partner in this station says,,,,,
> >
> > Picking up a K3 tomorrow.
> > We will be using it at field day. It has a 400 Hz roofing filter, 100
> > Watts, internal tuner, USB interface, upgraded synth and the nice IO
> board.
> > Should be on the air for SST Sunday night.
> > Jim
> >
> > Now I know we will be clean on Transmit, To an OCFD.
> > That 400Hz roofing filter, How much will that protect US, see we will be
> > surrounded by several IC-7300's
> >
> > Would like to use the Band Pass filters to help but not sure if they can
> > handle the not perfect SWR that a typical OCFD will give us.
> >
> > I assume if we had to we can add an external manual tuner, to make the
> > SWR flat then go to the filter and rig.
> > And the external manual tuner would also add in some band pass filtering
> > effect too.
> >
> > Joe WB9SBD
> >
> >
> >
> >
> >
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> >
>
>
> --
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