When I listen on ANT1 and switching to ANT2 (not connected to anything) > I can hear pretty good signals on ANT1 on all bands! What is wrong?
regards, E72X, Jim Brown-10 wrote: > > On Wed, 24 Sep 2008 07:59:36 -0400, Monty Shultes wrote: > >>I have very high white noise in my K3 on 75 meters when connected to the >>serial port computer interface. Removing this connection greatly reduces the >>noise. If you use HRD, LP-BRIDGE, or any control software, you can also >>hear a pulsing noise related to polling the K3 over the serial port. I >>believe this can be lessened, but have not tried as yet. Here in Florida, >>USA, the level of thunder storms creates a naturally high noise level in the >>summer, but the effects described above are clearly noticeable. I use the >>Elecraft KUSB as serial interface. > > I suspect that either the computer or the K3 are dumping RF trash onto > your > serial cable, which, like any antenna, is radiating it, and your 75M > antenna is > picking it up. I suggest that you wind the serial cable around a toroid to > form > a common mode choke tuned to 75M. Fair-Rite #31 is the best material to > use, and > a 2.4-inch o.d., 1.4-inch i.d. toroid is a convenient size. Fair-Rite #43 > will > work, but you'll need more turns. This size is commonly called FT-240 in > the ham > world. > > See http://audiosystemsgroup.com/RFI-Ham.pdf for tutorial information > about how > and why this works, as well as measured data for chokes with 1 - 14 turns > around > #31 and #43 toroids. Ferrite beads clamped onto the cable will NOT fix > this > problem on the HF bands. They WILL help on 2M. :) > > 73, > > Jim Brown K9YC > > > _______________________________________________ > Elecraft mailing list > Post to: Elecraft@mailman.qth.net > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > > -- View this message in context: http://n2.nabble.com/AGC-behaviour-tp1114728p1116304.html Sent from the Elecraft mailing list archive at Nabble.com. _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
