At 1/24/2006 13:34, you wrote:
>Bob Dengler wrote:
> > At 1/19/2006 08:17 AM, you wrote:
> >> Ok guys I think I resolved the squeeling problem. I Got to the site
> >> this morning while guys were using the rptr and the problem was
> >> existing. When tuning the PA awhile back I noticed if you went to far
> >> one way it would oscillate (feedback, whatever) or go spurrious. Where
> >> I thought was the proper setting was just on the edge of this. I
> >> retuned the PA and all cleared up. Even cleaned up Rec'd audio just a
> >> bit.
> >> This has been happening more in the early mornings. May be the frost,
> >> dampness on the antenna created a slight impedence mismatch. Using a
> >
> > If slight antenna impedance changes are causing your PA to oscillate, your
> > PA needs servicing or replacement. At the very least you need an isolator
> > on the PA output so it "sees" 50 ohms across the band.
> >
> > Bob NO6B
>
>Correction:
>
>All good quality repeater installations should have an isolator on them
>to keep other RF from entering the PA from external sources and causing
>various problems.
Further correction:
All good quality repeater installations at shared communications facilities
("comm. sites") should have an isolator on them to keep other RF from
entering the PA from external sources and causing various problems.
>Ham repeaters should not be lower quality than commercial installations.
Like everything else in life, it depends on the requirements &
environment. It doesn't necessarily make sense to invest $20,000 in a
system placed in the middle of nowhere that only needs to cover 5 square miles.
>:-)
;)
>(All of our commercial 2-way and broadcast sites now have isolators
>listed as required equipment in the contracts these days anyway, so it's
>not an option for us to leave them off, anyway. Hams in rural areas
>with no other transmitters on the sites don't know how good they have it...)
One of my 3 440 systems is located at a comm. site. It has a dual isolator
& pass cavity on the TX. Although others at the site have chosen to do
otherwise, I'd never operate that system for one day without the isolator
in place. The other two sit alone at their respective sites; they do have
pass cavities in place but no isolators.
Bob NO6B
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