Re: BCI Filter Kits K9DP vs N4ELS : Summary
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Thanks for all of the investigation Chuck. I think that some of these filters have evolved through personal experience and some designs did not manifest until the experimenter solved his problem of interference. That said, depending on the strength of the local AM radio stations the strength of the filter needed may vary greatly. I do not have any of the Chinese SDR radios, but they might not need as much BCI filtering as my simple Tuna/Sprite receiver might, just my personal speculation. I also have not tested my Penntek TR-35 yet either as I have been down with this virus that makes my jaw and teeth feel like someone is pulling them apart with vice grips. However, if we can quit having large hail and tornadoes here in the Midwest, I want to throw out a wire for a quick POTA activation before we have to leave this state park on Monday while heading for Colorado.
Davey - KU9L
On Wednesday, April 19, 2023 at 03:01:36 PM EDT, Chuck Carpenter <w5usj@...> wrote:
As indicated by the data in the previous message the QRPme N4ELS BCI LPF is MUCH better for attenuating BCI received via your antenna than the K9DP filter. A suggestion:? Build the filter in a shielded enclosure and use best quality RF connectors, e.g., SMAs and BNCs. Also use coax, not audio cable. The BNCs used with the K9DP are good, snug fit and didn't rattle causing noise.
Proper grounding ensures that RF noise is conducted away to the ground instead
of being conducted from radiation. Shielding, filtering, and grounding are the immediate
answers to the question of how to stop radio frequency interference in electronic circuits.
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David Knapp