It seems there have been many people who are plagued by AM broadcast station interference from station antennas within a few miles
of their QTH. We designed a little high pass filter using Elsie to have a low end cutoff frequency of approximately 2.0 MHz and pass all frequencies higher than that. We also had some PC boards made
in 2 styles. One to use standard, through hole components and another (same size) that uses SMD components. Both have been tested at W0EB's QTH which has 2 AM stations (one 1KW and 1 10KW within 2.5 miles
of his place that wipe out the receiver in any uBITX hooked to an antenna. Either style works nicely and completely removes the interference.
We're not going to kit these, but since they use commonly available components we'll provide the blank PC boards (your choice of SMD or Through-Hole) for roughly cost plus postage.
This will amount to $5 for one board and $7 for 2 post paid in the US. If you order 2, you can get 2 of the same or 1 of each. The construction manual contains parts lists for
both styles. We got the through hole parts from Tayda out of Thailand and the SMD's from Mouser in the US.
Below is a picture of the two filter boards completed.
uBITX Broadcast Band Filter Construction Manual.
(An old NANO was used to support them just for photo purposes).
Simple LT SPICE plot of the filter's bandwidth.
Page, & all images copyright (c) 2018, 2019, 2020. Last updated by W0EB - 11/26/2020 @ 14:30 UTC