I agree with Eddie, only rare cases need a filter, and in many cases, the noise will bet there after the filter is installed. Robert _____
From: BVARC [mailto:[email protected]] On Behalf Of Eddie Runner via BVARC Sent: Monday, April 27, 2015 11:06 AM To: 'Bill Crowell'; 'BRAZOS VALLEY AMATEUR RADIO CLUB'; 'TDXS List' Subject: Re: [BVARC] Stop your alternator from whining... I would advise everyone to NOT run out and waste your money on these filters.. We install two way and ham radio gear professionally several times a week and I don't think I have used a filter like this on a regular basis since the early 80s.. now days the radios if they are installed correctly have very few problems. Icoms, Kenwoods, Yaesus, Alincos.. they are well designed for the cars we have now and prorblems rarely occur. when they do, we generally find a problem with the installation, or an old worn out car battery or some other variable that's easily fixed.. Maybe, once in a great while.but generally, no. Eddie Runner (NU5K) From: BVARC [mailto:[email protected]] On Behalf Of Bill Crowell via BVARC Sent: Monday, April 27, 2015 8:37 AM To: BRAZOS VALLEY AMATEUR RADIO CLUB; TDXS List Subject: [BVARC] Stop your alternator from whining... All, I've just installed my new Icom 2730H in my BMW X5 SUV. Despite the fact that the battery is in the back on BMW and wiring direct (please see this month's issue of QST), I still have receive audio alternator whine. This has been an off and on issue with a number of vehicles over the years. Because of the audio frequencies that we're dealing with, we need an iron-core transformer to give us enough choking. Finding these in a package that can comfortably handle 20-40A for mobile operations is darned difficult. Back in NC, I knew a guy who used to service police cars. He told me about the Motorola filters. I've tracked down some on eBay where the seller has found a warehouse of them NIB! http://www.ebay.com/itm/301163766083 You'll need to replace the electrolytic capacitor as the one inside has likely dried out. Any value close will be fine. There are also diodes to help suppress the reverse kick from starting the engine. The connection MUST be as follows: (battery + terminal) -> (fuse) -> (motorola uber filter) -> radio. In the event that the filter clamps down, we want the fuse to blow to prevent a fire. *** I have been using this setup in my other vehicle for years and my radios love it. Show your radio some love. Give it clean DC and it will make you happy. Bill, N4HPG
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