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
job is to match the impedance on one port to another impedance on the second port, period. Nothing gets
"tuned." They come in a variety of flavors ... a pair of push-pull 807's with a resonant tank and
a link feed to the antenna on open wire line is one. Everything that happens on the feed line [regardless of
it's construction] is the sole result of the complex impedance at the antenna feed point and the
characteristic impedance of the feedline. No magic.
73,
Fred ["Skip"] K6DGW
"Captain Obvious"
Sparks NV DM09dn
Washoe County
On 7/17/2020 5:14 PM, Ken Roberson via Elecraft wrote:
Kurt,
We are not tuning the antenna , we are matching the antenna to the coax at the
base of the antenna.
73 Ken K5DNL
On Friday, July 17, 2020, 7:10:32 PM CDT, Kurt Pawlikowski
<[email protected]> wrote:
Ken: In some respects, a "matching device" at the base of the antenna is a
tuner! {'-) It accomplishes the same function... {'-) k WB9FMC
On 7/17/2020 6:34 PM, Ken Roberson via Elecraft wrote:
Antenna tuners
I never use an antenna tuner , on the MF and LF bands realmen use a scopematch
at the
Output of the Power Amp and a matching device at the base ofthe vertical
antenna – HI Hi.
73 Ken K5DNL
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