Topband: 160 m inverted L

[Guy Olinger K2AV]

Hi Art,

Don't know  whether you are measuring L to FCP with nothing else connected
or measuring shack side of isolation transformer. You should be measuring
on shack side of transformer, with L and FCP connected.


A feed R of 1000 sounds way, way far off. A feed R of 40-50-60-70-80 would
be expected depending on the ground underneath and close dielectric
material. But R=1000 is way out of range.  You need to get that figured out
before you go any further.

I have also found that without telling me, some have been measuring in the
shack something like 50-100 feet of coax out to the transformer and L/FCP.
The impedance transformations of isolation transformer and quarter-wave-ish
coax run is like doing all your driving in reverse looking through the rear
view mirror. CAN be done, but you have to understand all the ugly, backward
and confusing aspects of pruning the far end of an antenna looking through
all that stuff.

Make sure on the transformer, with nothing connected to it, that the FCP/L
connections show a short between them, and the coax side SO239 shell to
center conductor shows a short, and that L to coax center conductor is an
open. It is possible that end of the bifilar winding can get flipped (very
rare on a commercial model, but does happen and very confusing until
rectified).

Your vert+horiz=160 is a little longer horizontal start point than typical.
1.68 MHz for outright resonance of wires of your dimensions by themselves
is not out of bounds.

The instructions for simple tuning of an L/FCP is to make vertical plus
horizontal 155-160 feet, and then remove a foot or 6 inches at a time from
the far end of horizontal, watching the nature of the change carefully each
time, until things get moderate at the coax side of the transformer. Do
**not** get in a hurry in this process. Record your sweep image with the
length at each check. Don't try to calculate the end from the change as if
it was linear, and make a giant leap. In experience, it is not generally
linear.

Will be happy to get with you over the phone if you think that would help.
Let me know and I'll pass along my cell number.

73, Guy K2AV

On Mon, Nov 7, 2016 at 4:05 PM, Art Heft <artandkaren at gmail.com> wrote:

> I finally got the inverted L up this afternoon.  Vertical dimension is 65'
> and the almost horizontal dimension is 95'.  I am using a very carefully
> built FCP and the commercial transformer.  My SARK 110 shows resonance at
> about 1.68 MHz but the resistive part is up around 1000 ohms.  Taken right
> at the antenna.  Doesn't seem right to me.  Any ideas?
> 73, Art K8CIT Hillman MI
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