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[Towertalk] Co-ax Traps

To: <>
Subject: [Towertalk] Co-ax Traps
From: (Maurizio Panicara)
Date: Wed, 25 Sep 2002 19:33:06 +0200
> I must disagree.  It is essential!  The trap is a parallel-resonant,
> nearly lumped, LC circuit.  The C stems mainly from the capacitance
> between the center conductor and the shield/braid of the coax.

I do not understand your answer.
Do You mean that a parallel resonant circuit used as a trap is not
reversible ?
Why ?

> >Although easy to build, coax traps have more losses than conventional
> >and don't handle much power.
> It's not a bad way to construct a trap, as long as you seal the ends
> of the coax to keep water out.  A little water will do a lot of harm,
> by corroding the braid and thereby causing a lot of loss.
> The polyethylene dielectric of coax makes a good high-Q capacitor.
> The large-diameter braid of coax makes a low-resistance conductor,
> which makes for a high-Q inductor.

I must disagree, its a compromise.
No one would use other than vacuum, air or eventually mica as a dielectric
to keep high the Q of a capacitor for RF use.
Polyethylene is much worse.

Mauri I4JMY

> 73 de Chuck, W1HIS
> >----- Original Message -----
> >From: "Peter Larsen" <>
> >To: <>
> >Sent: Wednesday, September 25, 2002 5:50 AM
> >Subject: [Towertalk] Co-ax Traps
> >
> >
> >>  I am thinking of building a set of co-ax traps to make a 40/80/160
> >>  inverted V.
> >>  I noticed in the ARRL antenna hand book that the braid is the input
> >>  and the center conductor is the out put.
> >  > Is this important, and why?

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