caesar@ge-dab.UUCP (Robert J. Caesar Jr.) (10/09/86)
In order to eliminate the "objectionable noise" injected into some
channels by the cable company, Radio Electronics June issue suggests
building a high-Q notch filter.
"... An RF carrier can cause severe crosshatching. Keying
the carrier causes an annoying flicker, and the resultant
picture looks like a severe case of TVI caused by a CB or
an amateur station. In order to provide service to a
subscriber, a high-Q cavity notch filter can be made out
of a coffee can and several feet of 1/8 inch copper tubing.
Those materials can be used to construct a helical
resonator; tuning the resonator is merely a matter of
adjusting its cavity of a notch at the interfering
frequency...."
Has anyone out there ever built one of these. Any ideas on how it works?
Is the can common and the input/output taken off the tubing? How might
one adjust the cavity of this high-tech device?
--
Bob Caesar
General Electric SCSD caesar@static.dab.ge.com
PO Box 2500 Room 4336 (904) 258-3043
Daytona Beach, Florida 32015 ...!mcnc!ge-rtp!ge-dab!caesar