Thanks, Brian, this is all excellent advice and it's actually what I did. Yes, my antennas (4) are verticals with about 32 ground radials each, and yes, there is a grounded cable entry plate with lightning arresters in the feed-through connectors. I recommend the procedure to others. George
On 9/8/2010 16:12, Brian Lloyd wrote: > On Wed, Sep 8, 2010 at 11:11 AM, George Works <wor...@hughes.net > <mailto:wor...@hughes.net>> wrote: > > I also see drifting noise hills, but mine got a lot smaller when > I put > several ferrites on the feedline near the antenna and near the radio, > and also put them on other cables to the radio. I suspect that ground > loops, especially big ground loops between my shack and antennas, pick > up this sort of noise for some distance around. > > > Actually, if adding ferrite beads to the feedline knocked down the > noise, the noise is probably being picked up and transported to the > antenna on the outside of the shield. This is common-mode conducted > noise. The solution is to install common mode chokes on the feedline. > The usual places to install chokes are: > > 1. At the feedpoint to the antenna; > 2. at the output of the transmitter or power amplifier; > 3. on either side of the ground point where your feedline enters the > building where your shack is; (You do ground the shields of your > feedlines where they enter your shack, don't you?) > 4. every quarter wave along the feedline. > > Of course, identifying noise sources and killing them is a good thing > too. You should put common mode chokes on both mains and output power > wiring of any offending noise sources as well. > > -- > Brian Lloyd, WB6RQN/J79BPL > 3191 Western Dr. > Cameron Park, CA 95682 > br...@lloyd.com <mailto:br...@lloyd.com> > +1.767.617.1365 (Dominica) > +1.931.492.6776 (USA) > (+1.931.4.WB6RQN) > _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/
