[160m] Inverted L question

Thu, 30 Jan 2003 12:21:27 -0600

If you make the top longer, you will find that the "R" value will increase
to closer to 50 ohms.  The inductive reactance will be quite high.  However,
using a 500pF capacitor at the feedpoint will tune out the inductive
reactance quite nicely.

If you have a way to measure the feedpoint (MFJ, Autek, etc.) as you are
building it, make the top quite long and trim to the point where the
reactance is nill.  Without using this trick, you will have a very low
impedance to match (<10ohms?).  I've built a couple this way with great
success.  They key is being able to measure the feedpoint and having access
to a large 500pF doorknob type capacitor.

I built a system like you describe a few weeks ago with a friend.  Up 45'
and out 125' worked out to be about 45 +j0 using a 500pF cap, which actually
measured about 600pF at 160M.  We cut it about 20' longer and trimmed to
"dial-in" the feedpoint impedance.  The antenna tuned nicely at 1.840 and
was easily usable with an autotuner from 1.8 to 1.93 or so.

Good luck

Ford-N0FP
[email protected]

----- Original Message -----
From: "Lefczik, Larry D" <[email protected]>
To: <[email protected]>
Sent: Thursday, January 30, 2003 10:25 AM
Subject: [160m] Inverted L question

> I'm sure it's been discussed before, but I can't find anything in the
> archives.
>
> Hoping to put up a Ground-feed Inverted-L this weekend when the heat wave
> hits NJ (40 degrees).
>
> A few radials are in place and will be added next thaw.
>
> I was planning 129' total length with about 40' height and was hoping to
> feed directly with RG-8.  I have heard some are using 3/8 wave lengths.  I
> have the separation between the trees, about 125'.
> Is this a better antenna?  Is there any special treatment at the feedpoint
> or can a Antenna Tuner be used to match at the rig?
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