Return-Path: Received: from webterminator28.CRYSTALTECH.COM ([208.194.87.93]) by ns1.olsusa.com (Post.Office MTA v3.5.3 release 223 ID# 0-64832U3500L350S0V35) with ESMTP id com for ; Tue, 29 Aug 2000 10:51:22 -0400 Received: from ispchannel [24.142.76.4] by webterminator28.CRYSTALTECH.COM with ESMTP (SMTPD32-6.00) id A0158B01D0; Tue, 29 Aug 2000 08:00:37 -0700 Message-ID: <004001c011c9$a81c4ea0$044c8e18@com.ispchannel.com> From: "Larry Graves" To: "GlaStar Net" , "Robert L. Nuckolls, III" Subject: RF interference and fuel gauges Date: Tue, 29 Aug 2000 07:58:55 -0700 X-Mailing-List: lancair.list@olsusa.com Reply-To: lancair.list@olsusa.com Mime-Version: 1.0 <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> >> Can anyone in the know explain the possible causes of the fuel gauge needles jumping whenever a comm radio is transmitting? None of the other instruments or avionics seem to be affected by this phenomenon. The needles jump up about 1/3 to 1/2 deflection, even when the radio transmitting is an independent handheld with no associated wiring in the aircraft. We understand that the gauges are reacting to RF energy radiated by the transmitting antennae, but we'd like to understand the possible mechanisms of this interference and how we can shield the fuel quantity indicator system to prevent the problem. Would it be as simple as placing a circular magnet (choke) around the gauge wires, or wrapping the fuel sender unit in a metallic foil? Shielded cables/wires? Best Regards, Larry Graves AirCrafters Builder Assistance Center 140 Aviation Way, Watsonville, CA 95076 Tel: 831-722-9141 Fax: 831-722-9142 www.AirCraftersLLC.com >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> LML website: http://www.olsusa.com/Users/Mkaye/maillist.html LML Builders' Bookstore: http://www.buildersbooks.com/lancair Please send your photos and drawings to marvkaye@olsusa.com. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>