Thanks Bob. No electronic battery chargers here. The only switching supply in my home is in my computer, and no, the computer is not causing the buzz. Your comments made me research some other possibilities - one being my alarm system with a liner circuit for charging the standby battery (using a simple three leg regulator). This seems to be causing most of the buzzing. But when the alarm system is powered down, there still remains some areas that have buzzing - although fewer occurrences now.
--- In Repeater-Builder@yahoogroups.com, "Bob M." <[EMAIL PROTECTED]> wrote: > > Not that this would be your problem, but I had a > strange signal floating around my house. It ran from > about 400 kHz to 4 MHz and maybe even a bit higher. > Signals were occuring every 101.2 kHz and were solid > carriers with 1-2 kHz of FM at a 60 Hz rate. I turned > every circuit breaker off one at a time and it never > went away. Then I pulled the main breaker - the > signals disappeared. > > The only thing that's not on its own breaker is the > generator transfer switch which is between the main > breaker and the distribution panel. Inside that box is > the electronics and a battery charger. I pulled the > wires going from the charger to the generator (40 ft > of #12 wire in plastic conduit) and the noise went > away. Turns out the 6 amp charger uses a switching > power supply that runs around 100 kHz. > > I tried two clip-on ferrites on the DC wires - no > appreciable help, maybe a couple dB. > > I have since bought another charger that uses a linear > power supply with an ordinary transformer and plan on > swapping them. > > Bob M. > ====== > --- 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 > > > > > > On Nov 21, 2005, at 5:43 PM, n60sb wrote: > > > > > > > I am using two Icom IC-2AT hand held radios as a > > low power "one way" > > > > repeater system. This system provides a full > > quieting signal into a > > > > local repeater whenever I use another HT around > > the house. The one > > > > way transmitter uses a yagi antenna in the attic > > and the frequency is > > > > set to a local repeater input frequency. The > > one way receiver uses a > > > > simple rubber duck antenna (high sensitivity is > > not an issue here) and > > > > listens to an offset frequency opposite that of > > the local repeater > > > > thus allowing me to listen to the local repeater > > directly on my HT. > > > > Everything works great with one exception. > > Whenever I stand in a few > > > > specific locations around the house, an > > irritating buzz is transmitted > > > > from the one way repeater. > > > > > > > > I did some additional testing and discovered > > that several other two > > > > meter receivers (various brands) in my home will > > receive a buzzing > > > > sound whenever I transmit from several specific > > locations within my > > > > home using various brands of hand held radios. > > The exact location > > > > where the HT produces the buzz varies with > > different receivers that > > > > are located in different places in my home. > > Incidently, it makes no > > > > difference if the output power of the HT is > > increased or decreased. > > > > > > > > This problem may be obvious to others, but my > > friends and I are unable > > > > to figure it out. If I knew what was causing > > this buzz, I may be able > > > > to resolve same. Any comments or help would be > > welcomed! > > > > > > > > 73! > > > > > __________________________________ > Yahoo! Mail - PC Magazine Editors' Choice 2005 > http://mail.yahoo.com > 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/
