> "NORM KNAPP" <nkn...@...> wrote: > Yes, I don't know why the db-201 has such ridiculously > long radials, but that is how they were designed. Go > figure. I would like to know why though if someone knows... > 73
As mentioned before, the radials on a conventional Ground Plane are about 5% longer as a general rule. The DB-201 is specified as available down to at least 35MHz and is often cut to fit at some customer locations. Decibel is probably not going to have that many different part numbers for the same radiator when trimming to desired length via a cutting charge is probably more practical for everyone. Just as a sidebar... I had a horrible time installing UHF DB-201 antennas in situations where any type of metal is nearby (IE inside San Francisco Skyscrapers). In fact I had to stop using them because in the close proximity of other metal object the UHF models are horrible PIM (Intermod) generators. I didn't seem to have any problems with the low and high band versions but I would recommend people not use the UHF Version unless it's mounted well free and clear of and nearby metal objects. It's just something about the UHF DB-201 design, size and application that's a very confirmed grunge generator. cheers, skipp > ----- Original Message ----- > From: [email protected] <[email protected]> > To: [email protected] <[email protected]> > Sent: Sat Feb 20 21:31:38 2010 > Subject: [Repeater-Builder] Re: DB-201 Measurements for 6 Meters? > > > > > > > "NORM KNAPP" <nknapp@> wrote: > > > > Make the vertical element 50.5" from tip of loop to flat > > plate where the radials rest.. The radials need to be 73" > > long... Works for me. > > 73 > > In the standard ground plane world... the radials should only > "need to be" about 5% longer than the vertical element. However, > longer than 5% is not going to be a huge problem as being less > than 5% would be. > s. > > > ----- Original Message ----- > > From: [email protected] > > <mailto:Repeater-Builder%40yahoogroups.com> > > <[email protected] > > <mailto:Repeater-Builder%40yahoogroups.com> > > > To: [email protected] > > <mailto:Repeater-Builder%40yahoogroups.com> > > <[email protected] > > <mailto:Repeater-Builder%40yahoogroups.com> > > > Sent: Sat Feb 20 16:20:07 2010 > > Subject: [Repeater-Builder] DB-201 Measurements for 6 Meters? > > > > > > > > Hi Folks, > > > > I looked at the cutting 'chart' here on r-b, but it didn't > > make much sense. > > > > The antennas that I have are at 47.2MHz, and resonate exactly > > at that frequency. > > > > I removed the loop, and the measurements are from Tip of curve > > to the end of each piece is 54" and 58". > > > > The cutting chart says 58.875 & 83.250. > > > > I'm missing something! > > > > Ideas? > > > > Thanks, > > > > Tim > > >
