Return-Path: Received: from lanfear.nidlink.com ([216.18.128.7]) by truman.olsusa.com (Post.Office MTA v3.5.1 release 219 ID# 0-52269U2500L250S0V35) with ESMTP id com for ; Thu, 28 Oct 1999 10:16:11 -0400 Received: from enaila.nidlink.com (root@enaila.nidlink.com [216.18.128.8]) by lanfear.nidlink.com (8.9.0/8.9.0) with ESMTP id HAA03100 for ; Thu, 28 Oct 1999 07:20:24 -0700 (PDT) Received: from regandesigns.com (tnt132-117.nidlink.com [216.18.132.117]) by enaila.nidlink.com (8.9.0/8.9.0) with ESMTP id HAA14495 for ; Thu, 28 Oct 1999 07:20:22 -0700 (PDT) Message-ID: <38185B54.40EBFC66@regandesigns.com> Date: Thu, 28 Oct 1999 07:19:00 -0700 From: Brent Regan To: Lancair List Subject: Re: RADIO INTERFERENCE X-Mailing-List: lancair.list@olsusa.com Mime-Version: 1.0 <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> >> The part about the noise being low at sea level and very high at altitude makes me think it is related to the ignition system. As you climb the thinner air provides less of a dielectric in the distributor portion of the magneto. This increases the ionization of the air inside causing more EMI a la Marconi. I suspect that your P lead is improperly grounded. P lead wire should be shielded MIL-C-27500 (I used 18 gage for durability, ACS PN 11-14418) with the shield connected to the magneto case and the magneto switch ONLY. If you are using shielded wire that is grounded only at the source then the P lead will radiate LOTS of EMI. I would: 1) Verify P lead wiring 2) Try another radio (radio may be shifting frequency with altitude) 3) Land at high altitude airport and turn everything off except radio and Tx. Noise? My .02 Regards Brent Regan >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> LML website: http://www.olsusa.com/Users/Mkaye/maillist.html