At 09:47 AM 1/30/06, you wrote:
> I have a 2 meter & 440 system running off of one
> > in a very similar layout to yours (antenna only a few feet above the
> > equipment); the 440 outperforms 2 meters as expected. No desense
> > on either band.
>
>Hmm..
>It may be that mine is broken then. Wouldn't surprise me a great deal.
>Something interesting is going on in the bottom section of that thing,
>because when we had no screws in the section couplers (previous
>administration) we had still no significant reflected power, but lots
>of popping and cracking, and worse sensitivity.
>
>
>I have another similar antenna here, that just came down from the local
>club's 440 machine, I may try it up there and see what happens.
>Coverage on either band isn't what I would have expected, in either
>direction, but measurements at the bottom of the feedline seem to
>indicate that it should be performing decently.
One thought that I'll toss into the mix... just as something to
look for when you make a site visit.
If you have a loss in the feedline, it affects both ways. You get less
power at the antenna base, and any reflected power gets attenuated
by the same amount. So you could be sending a certain amount of
power up the pipe, and most gets there, a bad antenna reflects a good
chunk of the power, but when you look up the pipe you see zero (or
very little)reflected because the reflected is attenuated by the bad
feedline.
So you may want to put a termaline on the top of the feedline as part
of your site tests.
BTW, I've seen bad heliax-to-antenna jumpers do the same thing, so
try the termaline after the jumper as well.
Mike WA6ILQ
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