[HBR] El-Cheapo (and El-SIMPLO!) CW Filter

[john]

Eddy....where do you find the toroids!?

John K5MO


At 02:25 PM 7/20/2008, you wrote:
>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
>************************************
>Visit the HBR Receiver Web Site with over 100 pictures of receivers and
>construction notes...... via http://www.qsl.net/k5bcq/
>there is also a mirror (faster response)at http://k5bcq.edebris.com/
>
>
>Retrieve reflector archived data via 
>http://mailman.qth.net/mailman/listinfo/hbr