[Elecraft] LDG antenna tuner with 132 foot balanced dipole similar to a G5RV antenna

2012-10-26 Thread Ron Midwin
I recently bought an LDG AT600 Pro Automatic Tuner. I seem to be able to get a low VSWR on 80 & 40 meters, but on 20, 15, & 10 meters the best it will do is ~ 1.8:1. My "G5RV" (It's really a Van Gordon 80 meter all bander fed with 450 ladder line, 33 feet long, and then transitions to coax thru a

Re: [Elecraft] LDG antenna tuner with 132 foot balanced dipole similar to a G5RV antenna

2012-10-26 Thread hawley, charles j jr
t] on behalf of Ron Midwin [ronmidwin...@gmail.com] Sent: Friday, October 26, 2012 7:42 AM To: elecraft@mailman.qth.net Subject: [Elecraft] LDG antenna tuner with 132 foot balanced dipole similar to a G5RV antenna I recently bought an LDG AT600 Pro Automatic Tuner. I seem to be able to get

Re: [Elecraft] LDG antenna tuner with 132 foot balanced dipole similar to a G5RV antenna

2012-10-26 Thread Rick Stealey
Why not just help the tuner out a little? Put some inductance in series with the center conductor and see if it likes that better. If that doesn't work put some C in series and adjust it. Or some C across the line. Or some L across the line. Or some L in series and C across the line. You g

Re: [Elecraft] LDG antenna tuner with 132 foot balanced dipole similar to a G5RV antenna

2012-10-26 Thread David Bunte
Ron - This is not an area where I have much experience, but with 450 ohm ladder line I would have thought you would use something other than a 1:1 balun. A few years ago I experimented briefly with an 80 meter dipole, fed with 450 ohm ladder line. I tried it with a 1:1 balun and with a 4:1 balun

Re: [Elecraft] LDG antenna tuner with 132 foot balanced dipole similar to a G5RV antenna

2012-10-26 Thread Barry LaZar
Ron, The antenna you have is basically a good one. The problem you get into is that it's really an 80 meter dipole being used on all bands. This has been a popular configuration for many years. The issue is NOT SWR. The issue is transmission line loss in a high SWR situation. To avoid high

Re: [Elecraft] LDG antenna tuner with 132 foot balanced dipole similar to a G5RV antenna

2012-10-26 Thread N5GE
All, There's a trick I learned from an antenna engineer acquaintance recently for tuning 450 ohm feedline's with a 1:1 balun with 50 ohm coax feeding the TX. Here it is: 1. Assemble three RG11 coax lengths. One coax 6 feet 7 inches long, one coax 6 feet long and one coax 9 feet long. From thes

Re: [Elecraft] LDG antenna tuner with 132 foot balanced dipole similar to a G5RV antenna

2012-10-26 Thread Bob Stephens
What is the significance of using RG11 75 ohm coax vs 50 ohm? Sorry if this is a dumb question. Bob AF9W On Oct 26, 2012, at 10:39 AM, N5GE wrote: > All, > > There's a trick I learned from an antenna engineer acquaintance > recently for tuning 450 ohm feedline's with a 1:1 balun with 50 ohm

Re: [Elecraft] LDG antenna tuner with 132 foot balanced dipole similar to a G5RV antenna

2012-10-26 Thread W Paul Mills
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Impedance matching. See May be more than you wanted to know, but is easy to follow Smith Chart Tutorials. And does explain why you might want to do this. On 10/26/2012 01:23 PM, Bob Stephens

Re: [Elecraft] LDG antenna tuner with 132 foot balanced dipole similar to a G5RV antenna

2012-10-26 Thread Jim Wiley
All other things being equal, 75-ohm cable has less loss per foot than 50-ohm cable. This assumes that the cables being compared have the same diameter, length, operating frequency, etc. This is the primary reason that cable TV systems, telco inside-plant cabling, and other similar applicatio

Re: [Elecraft] LDG antenna tuner with 132 foot balanced dipole similar to a G5RV antenna

2012-10-26 Thread Jim Wiley
Sorry, meant to say 75-ohm, not 70-ohm in my previous post. - Jim, KL7CC On 10/26/2012 10:23 AM, Bob Stephens wrote: > What is the significance of using RG11 75 ohm coax vs 50 ohm? Sorry if this > is a dumb question. > > Bob AF9W > > > On Oct 26, 2012, at 10:39 AM, N5GE wrote: > >> All, >> >>

Re: [Elecraft] LDG antenna tuner with 132 foot balanced dipole similar to a G5RV antenna

2012-10-26 Thread Barry LaZar
The significance of the 75 Ohm line is a matching section that introduces a reciprocal impedance that brings the SWR to 1:1, or nearly so. However, this approach does not address the balanced to unbalanced issue. And, this is generally a one band match. A 1:1 choke type balun will still be need

Re: [Elecraft] LDG antenna tuner with 132 foot balanced dipole similar to a G5RV antenna

2012-10-26 Thread Don Wilhelm
David, I have seen several responses that suggest changes to your antenna setup, but not one that I can "warm up to". The choice of a 1:1 balun vs. a 4:1 balun depends on the feedpoint impedance and has nothing to do with the fact that the characteristic impedance of the ladder line is 450 ohm