From the ARRL Contest Update (which is a great source of technical news). This device might be of interest to AM DX’ers:
The Four States QRP Group has introduced the new BUZZ-KILL <http://www.4sqrp.com/buzzkill.php> kit for removing power-line buzz from an audio channel. The BUZZ-KILL is a comb filter - a notch at 60 Hz and every harmonic of 60 Hz. According to the website, "This is a compact, flexible design that can be used as a stand-alone outboard unit, or it can be easily integrated into an existing receiver (see manual for details). Its onboard audio amp is capable of driving a speaker or headphones. Gain is constant from 100 Hz to 5kHz, so it can be used with any CW, SSB or AM receiver." The circuit uses two analog delay lines to combine the signal with a time-shifted version of the signal, which creates a comb filter <https://en.wikipedia.org/wiki/Comb_filter>.(QRP-L mailing list) 73, Les Rayburn, N1LF 121 Mayfair Park Maylene, AL EM63nf Member WTFDA, IRCA, NRC. Former CPC Chairman for NRC & IRCA. Elad FDM-S2 SDR, AirSpy SDR2, Quantum Phaser, Wellbrook ALA1530 Loop, Wellbrook Flag, Clifton Labs Active Whip. _______________________________________________ IRCA mailing list [email protected] http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: [email protected]
