Drax,
Interesting thought- the reactance part of complex impedance. SWR on this
antenna is between 1.4 and 2, but the reactance varies between 22 pF and 53
pF farads. I don’t recall any comparative norms on reactance- any ideas?
Jim
-----Original Message-----
From: Drax Felton
Sent: Thursday, February 17, 2011 12:41 PM
To: 'Jim Jannuzzo' ; [email protected]
Subject: RE: [Flexradio] ATU Behavior
My 5k tuner will do this too. It happens when the antenna's reactance gets
too high.
It'll match, but as the power level peaks it's no longer a good enough match
and makes wacky things happen.
On a perhaps related note, PSDR does not show that I have a tuner in about
1 out of 10 starts. A restart then shows the tuner.
Happens on mine all the time too.
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Jim Jannuzzo
Sent: Thursday, February 17, 2011 11:51 AM
To: [email protected]
Subject: [Flexradio] ATU Behavior
F5K, w/ ATU; PSDR 2.0.16, Fast 4 core, Win 7/64
I’m puzzled by the behavior of the ATU in my 5K. When set to AUTO and a 2.0
SWR threshold, I still sometimes get the red “High SWR” warning. Shouldn’t
the ATU then start to tune, instead of just sitting there doing nothing? It
doesn’t, and I have to manually start the tune process.
Antenna is a dipole that is resonant on 40M. 2.0 or less SWR bandpath
extends throughout the band, according to a trusty MFJ 259b. Reflected
power at full TX level is 7 watts or less according to F5K meter.
I have four DX Engineering 41 ferrites on my antenna coax as it enters the
radio. (I had extras, and simply “store” them here.) No symptoms of
RF-In-The-Shack.
On a perhaps related note, PSDR does not show that I have a tuner in about 1
out of 10 starts. A restart then shows the tuner.
Resetting the database, and routinely withdrawing all power to the radio
overnight, does not change either symptom.
Is it my ATU settings, my ATU hardware, or is there more work to be done on
the ATU code?
Jim KJ2P
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