le monde du bruit
April 8, 2007 6:58 PM Subscribe
RF Filter (literally):
I'm using my trusty Sony ICF-2010
shortwave radio (1990 vintage) with a brand-new Edirol R-09
digital recorder. Unfortunately, once I hook up the R-09, it spits up digital noise all over the bands.
posted by mykescipark to technology (6 answers total)
In this case, the predominant noise is like a kind of fast chuffing, a trilling, outboard motor-like sound. The sound changes its rhythmic qualities depending on whether the unit is in standby (the chuffing) or in record mode (noise bursts seemingly whenever "packets" of data are being written to the flash card). It gets softer or louder as one touches or handles the unit - at its loudest when the unit is being handled, as the body acts as a conductor. At its absolute quietest, it simply acts as a noise floor which obliterates quieter signals and makes a significant sonic fingerprint on all but the most powerful of broadcasters.
This also happened with my Sony TCD-D7 and my Sony MZR70 Mini-Disc recorder, and not just on this radio: my tank-like Kenwood R-5000 also suffered from the ill effects of these digital recorders. Whether they use moving parts and motors (DAT, MD) or flash cards (MP3), each creates a distinctive brand of hashy noise. What can one implement to stop this egregious leakage?
I've tried all of the following:
- standard, off-the-shelf in-line and snap-on RF chokes;
- making the line extraordinarily long (up to 50') and moving the recording device far away from the radio;
- using a third device (such as a mixing board, analog cassette deck, etc.) as a "middle man" to offset any direct line-in interference;
- using both devices with their respective "wall warts" and with batteries, in combinations;
- calling both Universal Radio and Grove for expert advice.
In all cases, the noise just plows on through. I'm a bit vexed that nobody in the shortwave universe has figured this out by now. I'm not terribly solder-savvy, but I'm willing to learn to find a permanently workable solution. Any bright ideas, hive mind? Specifics, if you can...