Has anybody tried using a simple series L-C to notch out ONE offending AM broadcast station ? I'm talking about wiring from hot side of coax...to chassis / ground....like via a T connector etc.
On paper, it should work. Did some minor research, and one comment was that by using higher values of L would result in higher Q..and a deeper notch. Another comment stated to use some initial values, like what spits out on a L-C online calculator for practical values..... then multiply one value by the other...then take the square root of the result. Then you ended up with 2 x numerically equal values of L + C..... and supposedly the greatest notch depth. On software, I tried several values..from one extreme to the other, and they all resonate on the same freq. Also tried in software, using 2 x numerically same values..and it too, also resonates on the same freq. The rationale behind all of this is... in some cases, there is only one offending AM broadcast station. Typ HP filters offer little rejection towards the top end of the AM broadcast band..... like 1200-1710 khz. I would like to try it, but am still confused as to which combo (using practical values) will result in the deepest notch. It would have to be wide enough to remove the 20 khz wide AM signal. A fixed coil + variable cap, or padded variable cap could be used to fine tune the notch freq. Perhaps 2 or more LC filters could be used in parallel, to notch out 2 or more offending stations ? Jim VE7RF _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
