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--></style></head><body lang="EN-US" link="#0563C1" vlink="#954F72"><div class="WordSection1"><p class="MsoNormal">As we are considering building a 2000 mile permanent Appalachian Network for APRS Hikers in the woods, the idea of frequency comes up. Here are the driving thoughts, but are they correct?</p><p class="MsoNormal"> </p><p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><span style="mso-list:Ignore">1)<span style="font:7.0pt "Times New Roman""> </span></span>VHF works better through trees,</p><p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><span style="mso-list:Ignore">2)<span style="font:7.0pt "Times New Roman""> </span></span>144.39 works to an IGATE sometimes but is way too crowded for reliability</p><p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><span style="mso-list:Ignore">3)<span style="font:7.0pt "Times New Roman""> </span></span>Some IGates are not two way. 144.39 is just not good performance</p><p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><span style="mso-list:Ignore">4)<span style="font:7.0pt "Times New Roman""> </span></span>But VHF from a rubber duck antenna is poor</p><p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><span style="mso-list:Ignore">5)<span style="font:7.0pt "Times New Roman""> </span></span>But full size 2m antennas on a hikers HT is a disaster in the woods</p><p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><span style="mso-list:Ignore">6)<span style="font:7.0pt "Times New Roman""> </span></span>So is UHF the better trade? A rubber duck works “better” at UHF than VHF</p><p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><span style="mso-list:Ignore">7)<span style="font:7.0pt "Times New Roman""> </span></span>UHF is easier to fit into existing APRS digi sites</p><p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><span style="mso-list:Ignore">8)<span style="font:7.0pt "Times New Roman""> </span></span>My measurements show a 7 dB performance hit at 9600, so we will start at 1200</p><p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><span style="mso-list:Ignore">9)<span style="font:7.0pt "Times New Roman""> </span></span>But the goal will be to operate at 9600 for better long haul reliability and capacity.</p><p class="MsoNormal"> </p><p class="MsoNormal">See the plan: <a href="http://aprs.org/ec9600net.html">http://aprs.org/ec9600net.html</a></p><p class="MsoNormal"> </p><p class="MsoNormal">SO today, I did a quick test to compare an HT rubber duck to a calibrated spectrum analyzer to see if the 9 dB greater path loss at UHF was in fact improved by the poorer effectiveness of the rubber duck at VHF. My test was inconclusive and limited by reflections.</p><p class="MsoNormal"> </p><p class="MsoNormal">At first the UHF signal was in fact 9 dB worse than the VHF implying the path loss was correct, but also implying the rubber duck was as good at VHF as it was at UHF (that cannot be!). So we repeated the test and found we could get UHF performance anywhere form -9, -7, -2 and even +3 dB compared to the VHF. I ran out of time. Need to do more testing. Also a human hand was not holding the HT. I was using 3 element beams on the SpecA to reduce reflections…</p><p class="MsoNormal"> </p><p class="MsoNormal">So before I waste any more time, does anyone have a reference to the actual on-air quantifiable performance of the rubber duck on the two bands and not just a “it works” comparison?</p><p class="MsoNormal"> </p><p class="MsoNormal">DONATIONS: Also, when we come up with the design, we will also be asking for DONATIONS to support the network and in particular, we would love to find someone that has a stack of 16 UHF commercial grade radios we could get for the purpose cheaply. We will be doing 9600 baud eventually and want to have a consistent interface…</p><p class="MsoNormal"> </p><p class="MsoNormal">Bob, WB4APR</p><p class="MsoNormal"> </p></div></body></html>