Topband: Inverted L improvement question - Part 2

[Mike Waters]

Hello Grant,

Your advice is spot-on! Elevated radials MUST NOT be connected to ground.
Perhaps that's one of the reasons why Todd's inverted-L is working so
poorly.

Another important thing is to have a GOOD choke balun right at the
feedpoint. *We need to keep the current off of the feedline shield.*

 This is how I made my own inverted-L work, per the advice of many
Topbanders a whole lot smarter than me:
http://www.w0btu.com/160_meters.html (scroll down).
It describes the common-mode choke. There are photos there (click the
links).

73, Mike
www.w0btu.com

On Fri, Dec 28, 2018 at 6:49 PM Grant Saviers <grants2 at pacbell.net> wrote:

> Modeling I've done shows it a bad idea to have in ground and elevated
> radials connected together, but that is not clear from what you
> described.  Then with the elevated separate, moving the feedpoint up at
> least 8', to 12' is better and elevated radials run out at that height.
> I think it is a tossup if the "flying V" feed is used - ie gain some
> vertical wire length by feeding near ground and then angle the wires to
> the the elevated ones say at 45 degrees.  It doesn't hurt to have the
> buried radials below the elevated but doesn't help either according to
> NEC4.2 models I've tried.  The elevated ones shield the currents enough
> from the ground in the near field.
>
> Check out what N6LF has to say about elevated radials (if you haven't
> already)  antennasbyn6lf.com
>
> Then develop an swr curve with 5 watts from your rig.  Better than nothing.
>
> Borrow a different antenna analyzer to try or put a quality BCB filter
> on the input.  You need one anyway.  A two port VNA can calibrate out
> the filter.
>
> It is also hard to compare antennas unless the A/B testing is real time.
>   This week proves that on 160, one night nada to EU, Thur night was
> pretty good and I missed the killer opening on Wed according to PNW
> reports.
>
> Grant KZ1W
>
> On 12/28/2018 15:35 PM, Todd Goins wrote:
> > I originally started this thread and I want to once again thank everyone
> > who provided input and advise both privately and on the reflector.
> >
> > So the 100' tall vertical with the 30' horizontal loading wire works
> > **horribly**. I have about a week with it now every evening and it is
> much,
> > much poorer transmitting (and receiving, as expected I guess) than the
> 43'
> > vertical with the 90' horizontal.
> >
> > Since everyone was united in the opinion that I needed a dedicated
> > receiving antenna I put out a 200' BOG (pointing east) with the
> transformer
> > and terminating resistor from DXEngineering. The BOG is really quiet
> > (S1-S2) compared to the verticals and it hears "okay" but I wouldn't say
> it
> > was great by any means. The Stew Perry tomorrow will give me better
> chance
> > to evaluate it.
> >
> > Back to the 100' vertical. Since it wasn't working being tied into the
> > buried radial field I was using for the 43' (PSK Reported showed dreadful
> > performance) I decided to take a different approach and made it have an
> > elevated feed point at about 7' above ground and I ran three 130'
> elevated
> > (also around 6' to 7' high) counterpoise wires. This antenna works a
> little
> > better but still not nearly as good as the 43'.
> >
> > Several people asked me to make R/Z measurements of the antenna at the
> feed
> > point. I'd love to provide that info but my Comet CAA-500 MarkII antenna
> > analyzer is being totally killed on 160m by a 27.5KW AM broadcast station
> > that is about 2 miles from my QTH. It will not work. The analyzer has
> been
> > fine on 6-40m and sometimes works on 80m but 160 is no-go. So I can't get
> > the reactance and resistance values you all wanted.
> >
> > So, here is my question. The one easy modification I can make to the
> > antenna, now that I have elevated radials connected, is that I can
> elevate
> > the feed point. I can raise it to about any height necessary. Would this
> > make any difference? I would lengthen the horizontal wire by whatever
> > distance I raised the feed point, right? Any ideas or am I just chasing
> my
> > tail?
> >
> > Thanks for reading and any advise you can give.
> > 73,
> > Todd - NR7RR
>
>