Forty-9er BCI Filter
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All: I live close to a 50KW AM station and my Forty-9er does a great job of picking it up. I have an article coming out in CQ that is a broadcast interference filter for the AM band. That article, however, is designed around a BCI filter capable of handling over 100W and uses hand-wound toroids, which is overkill for the Forty-9er. Instead, I changed the inductors to axial lead chokes and ceramic capacitors. While it is not maximized in the theoretical sense, it uses a 5 pole Chebyshev design and has less than a 0.04 insertion loss, but knocks the slats out of the AM band. The photos show the values and plot for the filter. The inductors and capacitors can all be purchased from Tayda Electronics (http://www.taydaelectronics.com/) for about a dime each. Connect it between the BNC and antenna connector on the Forty-9er. Even with shipping, it's still reasonable. You can construct it on perf board. Let's know how it works for you. 73, Jack Purdum, W8TEE ? |
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There are photos of a BCI filter that should work with the Forty-9er posted on this site along with the values. It will be less expensive to make, since the CQ article is for 100W and uses hand-wound toroids. The parts are: 2 ? 1500pF ceramic caps 2 ? ? 560pF ? ? ? ? ? ?" 2 ? ? ?1.8uH inductor, axial lead 1 ? ? ?1.5uH ? ? ? ? ? ?" The inductors and capacitors can all be purchased from Tayda Electronics (http://www.taydaelectronics.com/) for about a dime each. Connect it between the BNC and antenna connector on the Forty-9er. The insertion loss is about 0.04dB, so you won't even know its there. Take a look at the photos. Jack, W8TEE From: "dfine01@... [SoftwareControlledHamRadio]" To: SoftwareControlledHamRadio@... Sent: Sunday, April 10, 2016 1:08 PM Subject: [SoftwareControlledHamRadio] Re: Forty-9er BCI Filter Jack,
Is there a schematic/parts list available for the BCI filter available yet, or are you waiting for the article to appear in CQ? (which month??)?? I just let my subscription expire and will have to renew or pick one up at the local parts house tomorrow if the is in the current month??? I am experiencing some minor BCI with the 49er. Dave |
jjpurdum