I think you have a bad connector somewhere - I will guess there is a pl259
going into that choke balun - you may have a poorly made connection to the coax
which shorts out at high power. I don't think Arcing to the tree would happen
especially that abruptly.
Sent from my iPad
On Nov 28, 2012, at 0:49, Ashton Lee <Ashton.R.Lee@hotmail.com> wrote:
> So I am trying to get set up better on 160 meters. I now have two antennas up
> (pretty well separated). One is an Alpha Delta DX A sloper hung in a tree
> with a grounding wire led to a ground rod and small radial field. The other
> is an inverted L on a good radial system of about 2000 feet in various
> lengths of about 50 feet each as fit the yard. Both are resonant at about
> 1.830 .
>
> The sloper loads fine all the way up to 1500 watts. The inverted L loads just
> fine to about 700 watts and then causes the Alpha amp to fault out. I think I
> am getting a sudden change in antenna impedance. The antenna is fed through a
> 5 KW rated choke balun. The feed line exits the base between radials. I've
> tried various feed line lengths, I've replaced every component in the system
> except for the antenna wire. The antenna does climb along the branches of a
> tall pine before L-ing outward at about 55 feet. I think the problem is worse
> at night time when things are cold (and perhaps more humid).
>
> What I see on the amp is output power suddenly seem to surge to 2500 watts,
> and reflected power jump from a few watts to over what the amp can read… then
> in a flash the amp faults out. This all happens with only about 20 watts of
> drive, so the amp can't actually be putting out 2500 watts unless something
> very strange has happened. As I noted, using the other antenna all is good.
>
> I need to get the inverted L working since it seems to have substantial
> receive gain vs the sloper, so I assume it will be equally better on transmit.
>
> All advice is welcome. Am I likely to be "arc-ing" to the tree branches?
> Could the wire be the problem? Do inverted L's have trouble with full power?
> The same wire worked fine for the last few years, but fed against a much
> lesser radial field and run through a less dense, lower tree.
>
> I'll be trying everything I can think of tomorrow afternoon, starting by
> trying to minimize contact with the tree branches. All suggestions welcome.
>
> 73
> KQ0C
> Ash
> _______________________________________________
> Topband reflector - topband@contesting.com
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