Uglies DON'T WORK WELL!!!! Use ferrite
Jim W6AIM . -------- Original message -------- From: Jan Ditzian <[email protected]> Date: 11/22/2015 4:33 PM (GMT-08:00) To: [email protected] Subject: Re: [Elecraft] RFI in audio chain 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<http://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]
