Thanks guys The j11 ohms is the best I can get period. I was able to get j0 when the cap was outside of the steel enclosure with a better bandwidth. Maybe I should throw my $400 enclosure and find a fibergla$$ enclosure. But as others have indicated I should probably just live with it.
Do you think a smaller (physically) vacuum cap would have less interaction with the steel enclosure. The one I have is only 3" round and 6" long. The air variable I'm using is 13" long and 7" round at mesh Carl AG6X Sent from my iPhone > On Feb 21, 2014, at 7:11 PM, "ZR" <z...@jeremy.mv.com> wrote: > > The only benefit of getting it better would be a bit more 2:1 VSWR bandwidth > to keep the amp happy but even then there is sometimes a gotcha when tuning > an antenna. > > Carl > KM1H > > > > Subject: Re: Topband: Shunt feeding the Skyneedle - new developments > > > Well, you can do all that, Carl > > But if your series variable capacitor is not maxed out (fully meshed) if > you can increase the capacitance enough to get to j0, you would be at 45 > +j0 and on a 1.1:1 VSWR circle. No point int trying to do better than > that!! > Otherwise, just increase the series capacitance to bring that -j11 as > close to j0 as possible and take that! You'd be so near perfect that there > would be no real point in going further! > > Your time and efforts might be better spent working on your radial field! > > 73, > Charlie, K4OTV > > > -----Original Message----- > From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Carl > Braun > Sent: Friday, February 21, 2014 8:46 PM > To: Charlie Cunningham; 'Tom W8JI'; '160' > Subject: Re: Topband: Shunt feeding the Skyneedle - new developments > > Thanks to all who replied > > Tom W8JI, your comments on the metallic panel and the static bleed choke > make sense. I was so pleased with the FLAT SWR reading with the variable > cap outside the panel but I guess I can live with the slight SWR. (Thanks > Charlie K4OTV). I have a Nye Viking monster tuner but I hate to use it as > my Henry amp seems to load strangely when I have it inline so I think I'll > just live without it. > > Can I add some coax (coiled) to bring the X down on the -j11 reading? I did > this with the old Telrex and brought the X right down and out of the pic. > I'm sure Ill need much more than I would on 14MHz but I think I'd like to > try anyway. > > I'm still going to drop the tower down and add two more gamma wires to > create a cage and I still have the option of pulling the gamma wire(s) away > from the tower another 8-10 inches to add a few more ohms to the equation. > > I'm having fun with the experiment. > > Right now I'm hearing the beginnings of the SSB contest with N7GP, WD5COV, > W6YI with the big signals so far. XE is the only DX I've heard. > > Lots of stateside calling stateside > > Carl AG6X > > -----Original Message----- > From: Charlie Cunningham [mailto:charlie-cunning...@nc.rr.com] > Sent: Friday, February 21, 2014 5:21 PM > To: 'Tom W8JI'; Carl Braun; '160' > Subject: RE: Topband: Shunt feeding the Skyneedle - new developments > > Well, Carl > > I plotted your 45-j11 load on a Smith Chart (normalized to 50 ohms) and it's > very near the origin on a 1.3:1 VSWR circle. Since you have a relatively > short feedline of LMR-400, You should be able to just tune it out at the > transmitter end of the line, and the LMR-400 line will be operating at such > a very low SWR (around 1.3:1 that the excess loss from a 1.3:1 VSWR at 160 > is completely trivial and negligible! It may not be completely > "intellectually satisfying to have -j11 of reactance at the load, but it > should match easily and the antenna should work very well! Enjoy! > > Sounds like that Array solutions static bleed is not as high in impedance as > we might wish! A large resistance might give you more satisfactory results! > > GL! Enjoy! > > 73, > Charlie, K4OTV > > > > > > -----Original Message----- > From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Tom W8JI > Sent: Friday, February 21, 2014 8:02 PM > To: Carl Braun; '160' > Subject: Re: Topband: Shunt feeding the Skyneedle - new developments > > Since then I've moved the variable capacitor inside the panel and mounted it > > to a ¾" think Plexiglas sheet mounted to the back plane with nylon bolts and > > washers. There is a 1" air gap between the Plexiglas and the backplane. I > now have seen the 42+j0 ohms change to 45 - j11 ohms...that's the lowest > reactance I can tune the capacitor for. Not really sure if its +j11 ohms > or - j11 ohms but I assume if the reading was + j11 I could continue to tune > > it out with the capacitor but I cant. > > Does the capacitor not play well with a steel enclosure?>>>> > > Any enclosure will change things, especially a metallic enclosure. Just > readjust the cap. > > <<<<The other strange situation I'm experiencing is when I connect my Array > Solutions static bleed choke to the feed thru insulator at the outside of > the panel to ground the resonant frequency jumps to 2.014 MHz at 25 +j0 > ohms...remove it entirely and I'm back to my 45 - j11 ohms.>>> > > The choke is completely unnecessary with a shunt feed tower. It won't help a > > thing, so leave it out. > > 73 Tom > > _________________ > Topband Reflector Archives - http://www.contesting.com/_topband > > _________________ > Topband Reflector Archives - http://www.contesting.com/_topband > > _________________ > Topband Reflector Archives - http://www.contesting.com/_topband > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 2014.0.4335 / Virus Database: 3705/7115 - Release Date: 02/21/14 > > _________________ Topband Reflector Archives - http://www.contesting.com/_topband