Hi All, Saving --- and READING! --- past issues of old radio magazines can be certainly worth the space and effort...
To-day, in the October 1970 issue of HAM RADIO (pp. 44 - 46), I stumbled upon a short piece by W4NVK entitled, "The Simplest Audio Filter". And simple it is, indeed...! Following the parameters therein for a 380-Hz CW audio frequency, I connected an 88-mH torroid coil in series with a 2-ufd. capacitor in the speaker lead of my Drake R-4 receiver...the results are REALLY quite amazing, and surprisingly effective. There are parameters given for CW frequencies of 1200-Hz, down to 380-Hz, but my ear prefers the lower tones, so I stuck with those particular values. If you have a spare 88-mH toroid laying about, along with some extra capacitors, this is a GREAT, easy-to-add-on adjunct that will only enhance the CW performance of your vintage commercial rig, or homebrewed creation...and it's OH SO EASY! ~73~ Eddy VE3CUI - VE3XZ
