Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site unccvax.UUCP Path: utzoo!watmath!clyde!burl!ulysses!allegra!bellcore!decvax!mcnc!unccvax!dsi From: dsi@unccvax.UUCP (Dataspan Inc) Newsgroups: net.physics Subject: Re: Need help for a noise problem Message-ID: <151@unccvax.UUCP> Date: Wed, 6-Mar-85 12:18:43 EST Article-I.D.: unccvax.151 Posted: Wed Mar 6 12:18:43 1985 Date-Received: Sat, 9-Mar-85 10:45:07 EST References: <223@ihlpg.UUCP> Organization: UNC-Charlotte Lines: 34 Way back in the 70's (before EMI was a consideration) I encountered the same problem fouling every attempt to make a tape recording. I have also encountered this whilst working for a radio station. A good bet is 1) the thermostat in your clothes dryer. It is absolutely amazing how much RFI/EMI this thing will make just arcing away under a 30 amp 220 volt resistive load. Some dryers have two (or more) for the various heat settings, etc. If you decide to bypass this thing, be sure to use the appropriate UL recognised component as the voltages can be very high here. 2) Ditto for electric blankets (but these usually go schpritt-schpritt at a 1-5 hz rate). 3) The SCR used as a control element in the heater that evaporates the kerosene off your non-plain paper copies. Old Minolta copiers are terribly bad about generating the most OBNOXIOUS rfi you have ever seen. The field from this unit was so strong that it coupled into the audio chain of an AM station located at the other end of the building. 4) Is your noise only on low band VHF channels? Sometimes, a defective HT insulator can make your life miserable. This is extremely hard to find and sometimes requires going from pole to pole with an AM radio and giving said pole a good swift kick (The technique to be used is not unlike that in kicking out streetlights. Three steps back...) . A change in sound character or modulation indicates you might have found it. Find this best with an AM radio and turn off stuff one at a time in your house. It will probably show up as above problem....HOWEVER, if you have ALUMINUM WIRING, you might just have a more serious problem which should be brought to the attention of a qualified electrician. dya