I have already eliminated the compact flourescent lamps as well as many wall warts and other various power supplies. Today, I discovered a large contributor of this anomalous buzz was from my alarm system charging circuit. The buzz was re-radiated around the house by the sensor wiring at various doors and windows. Sadly, the buzz still remains in a few areas within the home. At least I am gaining ground. Thank you and the others for all the helpful comments. I was inspired to investigate new areas.
--- In [email protected], Mike Morris <[EMAIL PROTECTED]> wrote: > > Got any compact florescent lights in the building? Many of those > run at other then 60 Hz. > > And I've seen a charger for a digital camera that was a full-wave > rectifier from the power line, and a single-chip switching supply > that charged the battery. It ran in the kilohertz range but had > trash from through the AM broadcast band with a very distorted > ac hum at about 500hz. > > At 10:26 AM 11/24/05, you wrote: > > >Good to know information! However, I have done extensive testing with > >two different hand held radios. The buzz will occur when both radios > >are operated with their own batteries and no external connections. > >For what it's worth, the buzz is not 60Hz. My guess would be around > >200Hz. > > > >Thanks. > > > >--- In [email protected], "Laryn Lohman" <[EMAIL PROTECTED]> > >wrote: > > > > > > My Yaesu handheld will often buzz when receiving the local repeater > > > when the charger is plugged into the side of the radio. I know what > > > you are thinking-- those cheap wall chargers are not filtered very > > > well, that's why I'm hearing buzz. That may be true, but the buzz I > > > am hearing is not from skimpy filtering of the DC feeding the radio. > > > I believe it is caused by the rectifier diodes in the charger, which > > > will cause a form of intermod to be produced, which basically > > > modulates RF at a 60 or 120 cycle rate. The level of buzz will vary > > > greatly as I move around the radio, touch the radio, etc. Certain > > > positions will produce intolerable buzz, others none at all. > > > > > > I know, the charger does not directly handle any RF. But it is > > > inevitably a part of your antenna system whether receive or transmit, > > > especially when using a duck on a radio. Therefore, RF on the wire to > > > the charger, and the AC side too, ends up in the rectifier diodes, and > > > is <modulated>. I've notices this phenomenon on other radios too, not > > > just my Yaesu, just as you have. > > > > > > I think you are experiencing the same thing that I do here. I haven't > > > <benched> the theory presented here to prove it right or wrong, but it > > > might be useful to try some small RF bypass caps on each diode in your > > > power supply(s)... Or, ferrite chokes on the wire from the charger. > > > > > > Laryn K8TVZ > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
