On 5/31/2013 12:35 PM, Jeff Ellis wrote:
Will adding a number of ferrite on the feed line help choke the RF? Will winding the feed line around a tube to make an air choke work? I guess that one is cheep enough I should just try it. Buying 10 or more ferrite to clamp to the line costs more;)
Wrong approach to chokes. Study http://k9yc.com/RFI-Ham.pdf and all the Power Point on Coax Chokes at http://k9yc.com/publish.htm
What about using a longer feed line? I really don't want to add a counterpoise and the instructions said it does not need one. I could use the 30' antenna wire it came with if that is going to help. I would not think so since its resonate on so many bands and tunable on the others.
I don't know what antenna you're talking about, but ALL end fed wires and nearly all verticals need some sort of counterpoise, regardless of what someone trying to sell you their antenna tells you to the contrary. It's simple physics. The fact that you don't have one is probably why you have "RF in the shack" -- the return current for that wire has nowhere else to go except back down into your rig.
Also, an antenna that ends in the shack will usually put a lot of RF in the shack if it's working well as antenna. That's its job -- it's INTENDED to radiate, and any antennas near it (your USB cable, other computer cables, audio cables to the computer, mic cables) will act as receiving antennas, and the received RF will be coupled into equipment by Pin One Problems (improper termination of cable shields). The solution is to choke those unintentional antennas. Again, see the RFI tutorial.
Another issue, if you're using a K2, is that the serial cable that was built from instructions (and the parts provided) used parallel conductors rather than twisted pair. That was a VERY poor design choice -- parallel conductors are very susceptible to RF and other noise, and twisted pair inherently rejects RFI and noise. That's why CAT5/6/7 cable is twisted pair.
73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
