russes@argus.DEC (Bob Russes * IND-3/C10 * 262-8365) (06/10/85)
*** HELP! *** I need advice in selecting a 1200-bps modem. I need a modem which is able to withstand the RFI interference from a 50,000 watt AM broadcast station which is located approximately 1-2 miles from my home. I currently have a Digital DF03 modem for use at home. However, given the amount of RFI interference at my location, it is effectively useless. Any suggestions would be **greatly** appreciated!! Should you need any other information, please ask! Bob Usenet: decwrl!dec-rhea!dec-argus!russes USPS: Bob Russes Telephone: (617)-467-8365 Digital Equipment Corporation 67 Forest Street -- IND-3/C10 Marlboro, MA 01752-9116
brian@sdcsvax.UUCP (Brian Kantor) (06/11/85)
Before you buy a new modem to get away from the broadcast interference, try a few of these tricks (they've worked ok in the past!): Wrap the modem in aluminum foil, and ground the foil. If your modem runs at all warm, you'll need some ventilation holes, but keep them small - use a toothpick to make little holes in the foil. Drop in at your local ham radio store or at radio shack, and get a couple of ferrite cores (they look like doughnuts) about an inch in diameter. Wind your phone line, power cord, and data cable each thru one of these (so you need three of the cores). It wouldn't be a bad idea to do this for your terminal cords and cables too. The cores act as filters and should block a lot of the RF that is probably travelling up the wires into the modem. Should cost about $1 apiece or so. If you're using a long extension cord to power your stuff, you might want to put cores and/or wrap it with foil too. See if the previous stuff helps first. If this doesn't work, you can add bypass capacitors inside the modem. This is potentially hazardous, as well as ruining the warranty, so get someone who is a hardware guru to help you. Sure its going to look funny sitting in its shiny foil wrapper, with doughnuts in the wires - but if you save the cost of a new modem, who cares how funny it looks? Brian Kantor UC San Diego decvax\ brian@ucsd.arpa akgua >--- sdcsvax --- brian ucbvax/ Kantor@Nosc