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 <gran...@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 > > _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector