Date: Thu, 06 Jul 2000 00:01:16 -0700
From: tignopsamnet
Subject: Re: Radio Interference


--------------2BE792938B005F7FFD3B6BFA Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Andrew Newton wrote: > Hi > > I'm new to this group so please tolerate if this has been answered before. I > have a 95 SAAB 900S 2.0 auto which came with a Sony radio / cassette. > Unfortunately this suffers from engine interference (and even when I depress > the brake pedal) whenever I listen to MW transmissions (FM is perfectly > clear). My dealer has trimmed the aerial but says he can do nothing more and > puts it down to poor signal performance in East Anglia (England) and the > location of the radio in the centre of the dashboard surrounded by all the > electrics. > > Any suggestions pls (UK drivers who are football fans will understand my > desire to correct this) > > Thanks in advance > Andrew > > P.S. In the UK why is there such a resistance to automatics (the one in my > car is very smooth) ; ) Apparently Sony did not install a decent noise blanker in the radio's circuitry. Short of doing this yourself - not an easy task if you have to ask about noise suppression - you can only try to reduce the impulses being picked up by the radio. First of all the FM will be perfectly clear as the noise pulses are Amplitude Modulation (AM), not Frequency Modulation. Amplitude Modulated modes (AM, SSB, CW (yeah, sure!), etc. will receive the impulse interference. Steps to reduce interference: 1) Ground the radio, the alternator ground lug, the battery ground lead and the motor solidly to the chassis of the car. Use heavy copper braid wherever possible. 2) Install a filter in the power lead to the radio. This should consist of a series (in line) choke (coil) and a shunting capacitor of approximately .25 microfarad. Choke values will have to be determined experimentally - just be sure the coil wire is heavy enough to carry the current you will be drawing. +12 Volts-------------------mmmmmmmmm-------------> radio (coil) | | | = capacitor | | ---- / / / chassis ground My best advice is to enlist the aid of a local Amateur Radio Operator who is experienced in mobil operation. I'll bet that he's solved noise problems far more severe than yours. Good luck, Tom, W2KVA --------------2BE792938B005F7FFD3B6BFA Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit <!doctype html public "-//w3c//dtd html 4.0 transitional//en"> <html>   <p>Andrew Newton wrote: <blockquote TYPE=CITE>Hi <p>I'm new to this group so please tolerate if this has been answered before. I <br>have a 95 SAAB 900S 2.0 auto which came with a Sony radio / cassette. <br>Unfortunately this suffers from engine interference (and even when I depress <br>the brake pedal) whenever I listen to MW transmissions (FM is perfectly <br>clear). My dealer has trimmed the aerial but says he can do nothing more and <br>puts it down to poor signal performance in East Anglia (England) and the <br>location of the radio in the centre of the dashboard surrounded by all the <br>electrics. <p>Any suggestions pls (UK drivers who are football fans will understand my <br>desire to correct this) <p>Thanks in advance <br>Andrew <p>P.S. In the UK why is there such a resistance to automatics (the one in my <br>car is very smooth)  ; )</blockquote> Apparently Sony did not install a decent noise blanker in the radio's circuitry.  Short of doing this yourself - not an easy task if you have to ask about noise suppression - you can only try to reduce the impulses being picked up by the radio. <p>First of all the FM will be perfectly clear as the noise pulses are Amplitude Modulation (AM), not Frequency Modulation.  Amplitude Modulated modes (AM, SSB, CW (yeah, sure!), etc. will receive the impulse interference. <p>Steps to reduce interference: <p>1)    Ground the radio, the alternator ground lug, the battery ground lead and the motor solidly to the chassis of the car.  Use heavy copper braid wherever possible. <p>2)    Install a filter in the power lead to the radio.  This should consist of a series (in line) choke (coil) and a shunting capacitor of approximately .25 microfarad.  Choke values will have to be determined experimentally - just be sure the coil wire is heavy enough to carry the current you will be drawing. <center> <p>+12 Volts-------------------mmmmmmmmm-------------> radio</center>                                                                    (coil)                   | <br>                                                                                              | <br>                                                                                              | <br>                                                                                             =  capacitor <br>                                                                                              | <br>                                                                                              | <br>                                                                                            ---- <br>                                                                                            / / /  chassis ground <p>My best advice is to enlist the aid of a local Amateur Radio Operator who is experienced in mobil operation.  I'll bet that he's solved noise problems far more severe than yours. <p>Good luck, <p>Tom, W2KVA</html> --------------2BE792938B005F7FFD3B6BFA--

Return to Main Index

The content on this site may not be republished without permission. Copyright © 1988-2019 - The Saab Network - saabnet.com.
For usage guidelines, see the Saabnet.com Mission and Purpose Page.
[Contact | Site Map | Saabnet.com on Facebook | Saabnet.com on Twitter | Shop Amazon via TSN | Site Donations]