That only applies to class A stations with protected skywave. Otherwise, something near 225 degrees is best.
Sent from my iPhone > On Jul 18, 2020, at 11:33, Fred Jensen <[email protected]> wrote: > > And the Texas Bug Catcher, Webster BandSpanner, SteppIR's, et al. All > represent changes to the antenna itself, which would also include changing > the height [e.g. cranking the tower up and down] and possibly cutting down > nearby trees or metal buildings [:=). Any change to the antenna itself or > its near-field environment will affect the feed point complex impedance. > This would include adding traps, inductors, and capacitors to the antenna. > > When you're done flutzing with the antenna itself, you are stuck with > whatever complex impedance you find at the feed point. AM broadcast > verticals are generally engineered for coverage near the edges of the market > area, meeting non-interference FS requirements, and minimizing > self-cancellation between the ground and sky wave. Something in the vicinity > of 195 degrees is generally optimal. They are not usually resonant and there > will be fixed matching network(s) at the base(s) ... AM broadcast stations > aren't known to QSY much. > > I'm not familiar with the TurboTuner however many mechanical antenna > adjusters operated by driving the phase angle between voltage and current to > zero, that is effectively bringing the antenna into resonance so the feedline > sees a resistive load. It's up to you to design the antenna so that resistive > load matches the characteristic impedance of the feedline OR put a matching > network between the feedline and the antenna feedpoint OR tolerate the SWR on > the line and put the matching network in the shack. Pick one. > > 73, > Fred ["Skip"] K6DGW > Sparks NV DM09dn > Washoe County > >> On 7/17/2020 9:44 PM, Rick NK7I wrote: >> Save one; the screwdriver antenna on my truck is tuned (coil adjusted) by >> the TurboTuner attached to my radio until a match is found. >> >> And an argument could be made that a SteppIR controller performs a similar >> function. >> >> The rest are matching circuits to compensate for the disparity of input to >> output. 😜 >> >> 73, >> Rick NK7I >> >> Email spiel Czech corruptions happen >> >>>> On Jul 17, 2020, at 7:00 PM, Fred Jensen <[email protected]> wrote: >>> >>> No antenna has, at any time, anywhere in any of our lifetimes, been >>> "tuned" by an "antenna tuner." So called antenna tuners are 2-port >>> impedance matching networks ... all of them ... and their ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
