I don't like 'ugly baluns', especially for the lower bands. If you do use one, you should wind the coax as a single layer solenoid, not a "hank" of coax. Also, as someone else suggested, you need a large number of turns for it to be effective on 80 m.
Vic 4X6GP/K2VCO > On 23 Nov 2015, at 2:32 AM, Jan Ditzian <[email protected]> wrote: > > In response to the balun recommendation from several hams, I apologize for > forgetting to mention that the vertical has an "ugly balun" both at the > antenna and near where the feedline enters the house. > > Part of the reason I put the question to this group, after first thinking > that the amps group could help, was the fact that the IC-730 shows no RFI, > while the K3 shows extreme RFI. > > Thanks, > > Jan, KX2A > >> On 11/22/2015 6:36 PM, John Kramer wrote: >> Jan >> >> The easiest, quickest and cheapest method is to wind yourself an “ugly >> balun” in your coax cable line. >> It must be located OUTSIDE your shack to choke the common mode currents from >> entering the shack. >> Wind about 15 - 20 turns of your coax on a 6” PVC pipe. This will give you >> about 2500 ohms choking >> impedance. >> >> If there is still RFI getting in the shack, then purchase a commercial choke >> either from >> http://www.balundesigns.com/model-1115d-max-choking-1-1-balun-1-54-mhz-5kw/ >> this will provide about 10 - 12 000 ohms of choking impedance, or buy one >> from >> >> http://myantennas.com/wp/product/cmc-130-3k/ >> This one will give from 12 000 - 15 000 ohms of choking impedance. >> >> These common mode chokes merely get plugged inline in your coax cable. >> Always better to locate >> them outside the shack >> >> 73 >> John >> >> >> >> >> On 23 Nov 2015, at 1:02 AM, Jan Ditzian <[email protected]> wrote: >> >> I have a problem that appears to be changing, but I could use some help. >> The problem is RFI in the audio input (microphone input) when I use my >> vertical antenna on 40 meters. Here is a rundown of what has happened: >> >> I have a 67-foot elevated vertical that I can use on 80 and 40, and it works >> fine on CW. However, on SSB, both bands, there clearly is feedback; there >> is no feedback on the other bands where I use a C3 yagi. Initially, the >> feedback was so bad that the rig would go into oscillation, and I had to >> turn the amp to standby. >> >> I recently purchased the new KSYN3A and decided to install it. I replaced >> the K3 with my IC-730 backup, using the hand microphone that came with the >> 730. The 730 did not have any RFI. I finished the modification and >> returned the K3 as the operating rig. Now, the RFI on 40 seems to have >> diminished substantially or disappeared, but it still happens on 75/80. >> However, it seems to be much less there as well. I do not suspect that the >> KSYN3A had anything to do with this, but perhaps I tightened connections >> better when I returned the rig to service. I also redid some ground >> connections. >> >> The microphone for the K3 is an Audio-Technica that works well everywhere >> else. It has a long cord, though. I put a few toroids on the cord near the >> microphone connector and that has possibly reduced RFI a little, but it is >> still there. >> >> Is there a possibility that a bypass capacitor is bad, or has someone else >> had the problem and solved it externally to the K3? For instance, has anyone >> found that a long string of ferrite beads has cured this problem? >> >> Despite decades of operating, I am hardly a troubleshooting hotshot, and I >> would appreciate guidance. >> >> Thank you, >> >> Jan, KX2A >> >> >> ______________________________________________________________ >> 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 >> Message delivered to [email protected] >> >> >> >> ----- >> No virus found in this message. >> Checked by AVG - www.avg.com >> Version: 2016.0.7227 / Virus Database: 4460/11045 - Release Date: 11/22/15 > > ______________________________________________________________ > 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 > Message delivered to [email protected] ______________________________________________________________ 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 Message delivered to [email protected]
