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Message-ID: <527CEE11.8070509@iup.uni-heidelberg.de>
Date: Fri, 08 Nov 2013 14:58:41 +0100
From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= <Stefan.Schaefer@iup.uni-heidelberg.de>
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References: <7E7DFBB4D102A04DB5ADC88D66628A4A0FC908D5@ICTS-S-MBX2.luna.kuleuven.be>
In-Reply-To: <7E7DFBB4D102A04DB5ADC88D66628A4A0FC908D5@ICTS-S-MBX2.luna.kuleuven.be>
Subject: Re: LF: remote antenna tuning
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Hi Rik,

Thanks for sharing your experiences.
I also didnt expect that this effect is so noticable.
What do you plan to do now?
I am using a current transformer at the cold end of the loading coil and 
have a small analog meter to show the current (peak). And my antenna 
even needs a re-tuning when QSYing from CW to WSPR...
How do you match the coil to the cable? Directly, a tap or a ferrite 
transformer?

Am 08.11.2013 14:03, schrieb Rik Strobbe:
>
>  By the way: remote tuning can be done correctly by tuning for 
> best SWR instead of highest RF current at the TX output.
>
> 73, Rik  ON7YD - OR7T
>

I think the best is to accurately match the feedpoint impedance (at 
resonance Z=R+j0) of the antenna to 50 Ohm, by using a ferrite 
transformer. Then the variometer position of best SWR is the best 
working point for the PA (and the LPF). Highest RF current at TX output 
can quickly destroy the PA, especially class-E types :-)

73, Stefan/DK7FC


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Hi Rik, <br>
<br>
Thanks for sharing your experiences.<br>
I also didnt expect that this effect is so noticable.<br>
What do you plan to do now?<br>
I am using a current transformer at the cold end of the loading coil
and have a small analog meter to show the current (peak). And my
antenna even needs a re-tuning when QSYing from CW to WSPR...<br>
How do you match the coil to the cable? Directly, a tap or a ferrite
transformer?<br>
<br>
Am 08.11.2013 14:03, schrieb Rik Strobbe:
<blockquote
 cite="mid:7E7DFBB4D102A04DB5ADC88D66628A4A0FC908D5@ICTS-S-MBX2.luna.kuleuven.be"
 type="cite">
  <meta http-equiv="Content-Type"
 content="text/html; charset=ISO-8859-1">
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  <div
 style="direction: ltr; font-family: Tahoma; color: rgb(0, 0, 0); font-size: 10pt;"><br>
  <p>&nbsp;By&nbsp;the way:&nbsp;remote&nbsp;tuning&nbsp;can&nbsp;be&nbsp;done&nbsp;correctly&nbsp;by&nbsp;tuning&nbsp;for
best&nbsp;SWR&nbsp;instead of&nbsp;highest&nbsp;RF&nbsp;current at the&nbsp;TX output.</p>
  <p>&nbsp;</p>
  <p>73, Rik&nbsp;&nbsp;ON7YD - OR7T</p>
  </div>
</blockquote>
<br>
I think the best is to accurately match the feedpoint impedance (at
resonance Z=R+j0) of the antenna to 50 Ohm, by using a ferrite
transformer. Then the variometer position of best SWR is the best
working point for the PA (and the LPF). Highest RF current at TX output
can quickly destroy the PA, especially class-E types :-)<br>
<br>
73, Stefan/DK7FC<br>
<br>
</body>
</html>

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