[TowerTalk] Modeling antenna traps

[Timothy Holmes]

Ok, thanks for the clarification. Since its all I have, I'll probably give
it a try anyway.

Thanks TIM
W8TAH

On Mon, Jun 6, 2016, 1:59 PM Gary Schafer <garyschafer at largeriver.net>
wrote:

> I don't think that you will have much luck with the MFJ used as a grid dip
> meter. You will need a decent grid dip meter.
>
> 73
> Gary  K4FMX
>
> > -----Original Message-----
> > From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of
> > Timothy Holmes
> > Sent: Sunday, June 05, 2016 5:40 PM
> > To: jim at audiosystemsgroup.com; towertalk at contesting.com
> > Subject: Re: [TowerTalk] Modeling antenna traps
> >
> > Hi Jim
> >
> > I guess that goes to the crux of my question, how do I go about
> > measuring
> > those parameters, and, once I have done so, how do I then model them.
> > This
> > is turning into quite an interesting discussion.  I should mention that
> > I
> > have an MFJ antenna analyzer with the grid dip coils if that will help,
> > as
> > well as a multimeter
> >
> > TIM
> > W8TAH
> >
> > On Sun, Jun 5, 2016, 6:33 PM Jim Brown <jim at audiosystemsgroup.com>
> > wrote:
> >
> > > On Sun,6/5/2016 1:20 PM, Timothy Holmes wrote:
> > > > I would like to model them so that I can properly adjust them to see
> > if
> > > it
> > > > is even worth my time, and what the performance will roughly look
> > like
> > >
> > > To model the antenna, you will first need to measure the traps to find
> > > their complete equivalent circuit. A trap is fundamentally an inductor
> > > with series resistance in parallel with a capacitor with parallel
> > > resistance. Near resonance, they simplify to parallel R, L, and C, but
> > > above and below resonance, we need to know the R in series with L,
> > > because these values affect performance on bands below the resonance
> > of
> > > the trap. And, of course, both Rs vary with frequency, thanks to skin
> > > effect.
> > >
> > > 73, Jim K9YC
> > >
> > >
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