How to fix RF modulator noise?

December 20, 2004 7:41 PM

I'm running my DVD player thru an RF modulator (my TV's fairly old, without RCA inputs). The problem: visual noise in the form of faint diagonal lines. Sometimes, repositioning the modulator will improve things somewhat but I'm never happy with the picture quality. How an I fix this? It's driving me nuts.
posted by davebush to Technology (6 answers total)

Your modulator may have the ability to choose a channel (usually 3/4). Try a different one.

Also, try new cables, as short as possible.

In the end, however, the best thing to do is probably to replace the TV...
posted by kindall at 7:44 PM on December 20, 2004

Agreed with kindall except, um, the last part. After trying a different channel on the modulator and new cables, check for something in your house or nearby that might be causing interference. A strong signal coming from just about any source of RF interference -- from a vacuum cleaner to one of those screwy ionic breeze things to a particularly strong TV station in your neighborhood to a ham radio operator -- can cause the kind of interference you describe, and a new TV may not fix it.
posted by eschatfische at 7:52 PM on December 20, 2004

If the above answers don't work, have you considered a new modulator? Buy one from Radio Shack, and return it if it doesn't solve the problem.

Also, check the video RCA cable from the DVD player to the modulator. If it feels cheap, it is probably unshielded.

For reasons I won't get into, I advocate that everyone buy things from Radio Shack and return them...
posted by bh at 8:00 PM on December 20, 2004

Try a better quality cable -- if you're using standard cable TV cable, it's much more prone to interference than a higher grade cable, like satellite TV cable.

Also ensure all your grounds are hooked up together solidly. You might want to try attaching the sheild of the cable to something grounded, like an unpainted part of the screw holding the electrical plate on the wall. Since so little consumer electronics in North America are grounded, sometimes this causes problems.
posted by shepd at 8:03 PM on December 20, 2004

Back in the old days, the cable going to the RF mod would be looped several times through a small iron donut to reduce interference. Choke coil?
posted by Enron Hubbard at 4:11 AM on December 21, 2004

Enron speaks of ferrite cores/chokes.
posted by NortonDC at 4:30 AM on December 21, 2004