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    <font size="-1"><font face="Courier New, Courier, monospace">Hi
        Helmut,<br>
        <br>
        Thanks for the information.  I'll review my existing bias
        switching arrangement and figure out a way to interrupt on high
        SWR.  I was concerned if there was a problem with still
        supplying RF to the AMP in this mode and certainly don't want to
        get into issues with hot-switching relays in the RF input
        circuit.<br>
        <br>
        I'm already using the PTT out pin and also using the open
        collectors for band selection on the associated LPF.<br>
        <br>
        Pete<br>
      </font></font><br>
    <div class="moz-cite-prefix">On 1/3/2017 7:21 AM, Helmut wrote:<br>
    </div>
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        <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"
            lang="EN-US">Pete, SWR protection is always a good idea to
            extend life time
            of your amp, hi. As drive reduction doesn’t solve a mismatch
            problem of
            the antenna, it’s better and safer to stop your amp by
            interrupting the
            amp’s bias. An analogue ALC is not provided on any HPSDR
            exciter board,
            because PowerSDR prevents any form of override of the
            board’s RF signal.<o:p></o:p></span></p>
        <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"
            lang="EN-US"><o:p> </o:p></span></p>
        <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"
            lang="EN-US">Pin1 (PTT-input) switches the Penelope to TX
            mode, when
            grounded. At pin 13 (PTT out) you’ll have access to the
            drain of a buffer
            FET to control  e.g. an external relay for accessories like
            amps, XVTRs etc. Please
            see schematics.<o:p></o:p></span></p>
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style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"
            lang="EN-US"><o:p> </o:p></span></p>
        <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">73,
            Helmut, DC6NY<o:p></o:p></span></p>
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            <p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext">Von:</span></b><span
                style="font-size:10.0pt;font-family:
"Tahoma","sans-serif";color:windowtext"> Hpsdr
                [<a class="moz-txt-link-freetext" href="mailto:hpsdr-bounces@lists.openhpsdr.org">mailto:hpsdr-bounces@lists.openhpsdr.org</a>] <b>Im
                  Auftrag von </b>n3evl<br>
                <b>Gesendet:</b> Dienstag, 3. </span><span
                style="font-size:10.0pt;
font-family:"Tahoma","sans-serif";color:windowtext"
                lang="EN-US">Januar 2017 00:18<br>
                <b>An:</b> HPSDR<br>
                <b>Betreff:</b> [hpsdr] External disable of Penelope RF
                output?<o:p></o:p></span></p>
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        <p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
        <p class="MsoNormal" style="margin-bottom:12.0pt"><span
            style="font-size:10.0pt;font-family:"Courier New""
            lang="EN-US">I'm contemplating some kind
            of high swr detection circuit in an external homebrew amp. 
            I've seen
            some designs that detect hi swr and block RF from the
            driving rig by using the
            ALC line.  Since Penelope does not have an ALC line, is
            there some way an
            external device can tell Penelope to cease generating RF? 
            <br>
            <br>
            I see Penelope has pin 1 on the DB25 connector labeled as
            "PTT Input -
            active when connected to ground" - but I'm not sure if this
            is relevant to
            this issue or how this pin is used.<br>
            <br>
          </span><span style="font-size:10.0pt;font-family:"Courier
            New"">Thanks,<br>
            <br>
            Pete, N3EVL<br>
            <br>
          </span><o:p></o:p></p>
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