[AMRadio] Odd tuning on 160M

Brett Gazdzinski Brett.Gazdzinski at verizon.net
Sat Jul 18 18:28:50 EDT 2009

Yes, I would also try adding 10 feet of coax and see what happens.

What sort of antenna's are they, high power AM (anything over 100 watts) 
will heat most antenna's into slag, and even good ones warm up and can 
change swr.

That is one reason why I went to resonant dipoles without a tuner, fed with 


----- Original Message ----- 
From: "M. K. Hess" <mkhess at kias.org>
To: <amradio at mailman.qth.net>
Sent: Saturday, July 18, 2009 1:16 PM
Subject: [AMRadio] Odd tuning on 160M

> Hi Folks,
> Here's a question that may need to get filed under "dumb", or maybe not, 
> but
> here goes!
> I have a V-Beam, a Vertical, and a Dipole, all capable of 160M operation. 
> I
> use a K3 as my exciter, an Alpha 91B as an Amp, and
> a Palstar AT-Auto for the tuner. The following happens with any of these
> antennas, including my dummy load (Heath CanTenna)...
> I have the Alpha in Stby, and key up the K3 w/ 10w through the Palstar to
> "whatever" load.... If finds a 1:1 match and all is well.
> If I advance the K3 to 120W all remains well... Can Xmit all day and 
> night,
> without issue. NOW....
> I fire up the Alpha 91B, and begin to tune it.... after a couple of 
> seconds,
> the Palstar starts to "re-tune" the load. I wait until it settles, and
> start the Alpha load again, same thing... this happens a few times until
> finally the Palstar thinks it's got a match, AND the Alpha thinks it's
> happily loaded...
> Finally, I hear someone calling.... I call back... as I'm talking, the
> Palstar starts re-tuning again and the Alpha usually goes into Hi-SWR
> shutdown...
> I fiddle with them for a bit, and try the call again.... Sometimes it 
> stays
> stable, most times it goes haywire several times during the QSO...
> WTF is going on!?!?!?!
> I have grounding out the ying-yang, and no RF back to the station, I have
> heavy duty parts from the shack to the antennas.. (See my web 
> www.n3eaq.net
> for details)
> This mostly seems to happen on 160 and 80 and DEFINITELY on 1885 when I'm
> trying to do AM!
> Any ideas!?!?!?! All help is appreciated!
> Mike - N3EAQ
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