Cutting and extending the loops did not work in my case. The SWR went up. I am useing a DB-224A on 147.225/147.825. The swr on TX is around 2.0:1. Despite this little problem, the repeater has great coverage.
----- Original Message ----- From: Repeater-Builder@yahoogroups.com <Repeater-Builder@yahoogroups.com> To: Repeater-Builder@yahoogroups.com <Repeater-Builder@yahoogroups.com> Sent: Sun Mar 22 19:35:39 2009 Subject: Re: [Repeater-Builder] Re: Decibel dipole array sweeps First, I have never played with a DB224. However, I have changed the length of a DB-212 to get it on 6-meters and it worked fine. I have heard that people have improved VSWR on the DB-224 by adding bolts through the ends of the loops to lengthen them. If that did indeed work, I would assume that cutting and extending the elements themselves would also work. The real problem may be with the harness - it may be causing the bottleneck. However, only being four elements, it shouldn't be too bad making up a new harness for that particular antenna. Chuck WB2EDV ----- Original Message ----- From: "NORM KNAPP" <nkn...@twowayradio.net <mailto:nknapp%40twowayradio.net> > To: <Repeater-Builder@yahoogroups.com <mailto:Repeater-Builder%40yahoogroups.com> > Sent: Sunday, March 22, 2009 8:26 PM Subject: Re: [Repeater-Builder] Re: Decibel dipole array sweeps >I tried adding length to the tubes on a DB-224A. I sacrificed some DB-420 >elements to do it. They fit perfectly. Inside the DB-224A. This was quite a >bit of work. The end results was not favorable. The SWR did not improve by >adding lenght. In fact it got worse. I don't know why. I have not tried >adding stubs to the ends yet. I also have not tried the adding a 50ohm >jumper between the top half and bottom half of the harness. > I had thought about putting spacers between the mast and the elements, but > haven't tried that yet. > Any comments? > Norm N5NPO > > ----- Original Message ----- > From: Repeater-Builder@yahoogroups.com > <mailto:Repeater-Builder%40yahoogroups.com> > <Repeater-Builder@yahoogroups.com <mailto:Repeater-Builder%40yahoogroups.com> > > > To: Repeater-Builder@yahoogroups.com > <mailto:Repeater-Builder%40yahoogroups.com> > <Repeater-Builder@yahoogroups.com <mailto:Repeater-Builder%40yahoogroups.com> > > > Sent: Sun Mar 22 18:10:31 2009 > Subject: Re: [Repeater-Builder] Re: Decibel dipole array sweeps > > I don't have any parameters. I was just suggesting this method > (lengthening > the entire element) as opposed to adding "stubs" to the ends of the > elements. Yes, the elements will be closer to each other either way, but > that may be a constraint of the phasing harness. If there was some slack, > the spacing could be increased as well. > > Chuck > WB2EDV > > ----- Original Message ----- > From: "Kris Kirby" <k...@catonic.us <mailto:kris%40catonic.us> > <mailto:kris%40catonic.us> > > To: <Repeater-Builder@yahoogroups.com > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > > Sent: Sunday, March 22, 2009 6:39 PM > Subject: Re: [Repeater-Builder] Re: Decibel dipole array sweeps > >> On Sun, 22 Mar 2009, Chuck Kelsey wrote: >>> A better method might be to actually cut each half of the element at >>> about the mid-point (not at the bend - at the straight section), then >>> slide some smaller tubing inside. Slide the element ends in and out >>> while testing and then use some stainless screws to attach things back >>> together at your new length. I suppose you could also measure the >>> length of the "extension" and cut that length from a piece of tubing >>> that is the same size as the original element. This would effectively >>> "hide" your repair and keep the element the same diameter for the >>> entire length. >> >> If you're adding pieces of metal to the ends of the antenna, you're >> effectively decreasing the spacing of the elements from each other. >> >> Give me some parameters and I'll run an analysis of it in the modeling >> program. >> >> -- >> Kris Kirby, KE4AHR >> Disinformation Analyst >> > > > > > > > ------------------------------------ > > > > Yahoo! Groups Links > > >
