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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>There have been discussions lately about plugs on Heathkit VTVM probes. Gary Clark is the Meter Master and his comments about the issue follow.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Vr,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Gary H. Harmon, Jr. - K5JWK - HAM Radio and ATARI Archaeologist<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>6003 Archwood<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>San Antonio, TX 78239-1504<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>(210) 657-1549 <home><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>(210) 884-6926 <cell and text><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>(210) 657-1549 <FAX with prior notification><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>gharmon@idworld.net<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>"Retirement = Every day is a Saturday except Sunday"<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>http://www.grissomroadcoc.org<o:p></o:p></span></p></div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'> Gary Clark [mailto:gc@sdlcforms.com] <br><b>Sent:</b> Thursday, May 26, 2016 9:45 AM<br><b>To:</b> Gary H. Harmon, Jr.<br><b>Subject:</b> Re: FW: [Heath] IM-18 Test Probe<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='font-size:14.0pt;font-family:"Arial","sans-serif"'>Gary,</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:14.0pt;font-family:"Arial","sans-serif"'>The combination probes that came with the Heathkit IM-11 and later VTVMs as well as EICO, PACO, RCA, B&K and others are no longer available. Nobody makes them any more. Furthermore, after some period of use they become unreliable, particularly causing problems on the lowest ohms range. The way VTVMs were designed previously, with three separate test leads was a far better arrangement.</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:14.0pt;font-family:"Arial","sans-serif"'>I refurbish and re-sell all different makes of VTVMs and I solve this problem with all of them the exact same way. I make a new test lead set and, if the VTVM has a microphone connector instead of a ¼ inch phone jack, I replace it with a phone jack.</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:14.0pt;font-family:"Arial","sans-serif"'>When I make the replacement test lead set I use high quality ¼ inch phone plugs I buy directly from China on ebay. (All the best stuff comes from China.) I use a standard mono phone plug and, even though the insulator spacing is much smaller than on those original Heathkit probes, I have never had a problem on the high voltage range. BUT, if you are worried about this, use a ¼ inch stereo phone plug and leave the ring part unconnected. This doubles the insulated spacing between the sleeve and the tip.</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:14.0pt;font-family:"Arial","sans-serif"'>In addition, unless the instrument in question has ac voltage ranges lower than 1.5 volts full scale there is no reason to use a shielded input cable. RCA sold a 4.5 inch VTVM for several decades that had three separate input leads and none of them used a shielded cable. You don’t need a shielded cable on the dc input anyway. Only the ac input can benefit from one, and then only on very low ac voltage ranges. </span><o:p></o:p></p><p class=MsoNormal><span style='font-size:14.0pt;font-family:"Arial","sans-serif"'>The way I make the replacement input lead set is shown in the drawing below.</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:14.0pt;font-family:"Arial","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt;font-family:"Arial","sans-serif"'>Regards,</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:14.0pt;font-family:"Arial","sans-serif"'>Gary Clark</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:14.0pt;font-family:"Arial","sans-serif"'>(The VTVM guy)</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:14.0pt;font-family:"Arial","sans-serif"'><img width=719 height=320 id="_x0000_i1025" src="cid:part1.163DD04D.25FC8CEE@sdlcforms.com"></span><o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><pre><o:p> </o:p></pre><pre>-----Original Message-----<o:p></o:p></pre><pre>From: Heath [<a href="mailto:heath-bounces@puck.nether.net">mailto:heath-bounces@puck.nether.net</a>] On Behalf Of Richard<o:p></o:p></pre><pre>Sent: Thursday, May 26, 2016 4:41 AM<o:p></o:p></pre><pre>To: <a href="mailto:Heath@puck.nether.net">Heath@puck.nether.net</a><o:p></o:p></pre><pre>Subject: [Heath] IM-18 Test Probe<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>The IM-18 test probe has a 1/4 inch phone plug as the interconnect with the<o:p></o:p></pre><pre>meter and the test probes. This plug has a wider insulator between the<o:p></o:p></pre><pre>center pin and ground on the plug in order to be able to handle the higher<o:p></o:p></pre><pre>voltage measurements. Has anyone found a reasonable replacement for this<o:p></o:p></pre><pre>plug? I have several meters without the test cable and I would like to make<o:p></o:p></pre><pre>some appropriate cables. The switchable DC / AC-Ohms probe can be replaced<o:p></o:p></pre><pre>with two separate probes, so that is not a problem.<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>Richard KC9UB<o:p></o:p></pre><pre>_______________________________________________<o:p></o:p></pre><pre>Heath mailing list<o:p></o:p></pre><pre><a href="mailto:Heath@puck.nether.net">Heath@puck.nether.net</a><o:p></o:p></pre><pre><a href="https://puck.nether.net/mailman/listinfo/heath">https://puck.nether.net/mailman/listinfo/heath</a><o:p></o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre></blockquote></div></body></html>