RFI in audio chain
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1. I have printed out Joe's directions and placed them in the K3 file -
for future reference. 2. Is you K3's chassis connector OK - loose ground? 3. Have a proper ground from the K3 to your station ground? 4. You are using the same feedline to test the K3 as used to test the 730? If not - do so. Everything needs to be eliminated. You have now eliminated the problem from causes in your station layout and the antenna/feedline to the K3 - as the complete same using the 730 works fine. True? Then the problem is with the K3 or something attached to it. 5. Disconnect everything from it except power, antenna, and mic. Test it. All clear - the RF is coming in on something other than the mic (plugged into the K3). Problem still there? 6. At this point, try an alternate mic and see if it works. If it works good - the problem is the mic/mic wire/connector. If it does not and you still have RFI - walk away for a while and cool down. Just a few simple steps that would apply to any radio in a similar situation. Bill W2BLC K-Line ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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> You have now eliminated the problem from causes in your station > layout and the antenna/feedline to the K3 - as the complete same > using the 730 works fine. True? Not true ... the Icom uses an electret mic, not the dynamic Audio- Technica. If the microphone is wired correctly, the issue is in the antenna system and probably requires improved common mode decoupling. Air wound solenoidal chokes are not sufficient in the most intractable cases *like elevated verticals*. Replace the elevated vertical with a dummy load. If the RFI is eliminated, the problem is in the antenna system. 73, ... Joe, W4TV On 11/24/2015 7:00 AM, Bill wrote: > 1. I have printed out Joe's directions and placed them in the K3 file - > for future reference. > 2. Is you K3's chassis connector OK - loose ground? > 3. Have a proper ground from the K3 to your station ground? > 4. You are using the same feedline to test the K3 as used to test the > 730? If not - do so. Everything needs to be eliminated. > > You have now eliminated the problem from causes in your station layout > and the antenna/feedline to the K3 - as the complete same using the 730 > works fine. True? Then the problem is with the K3 or something attached > to it. > > 5. Disconnect everything from it except power, antenna, and mic. Test > it. All clear - the RF is coming in on something other than the mic > (plugged into the K3). Problem still there? > 6. At this point, try an alternate mic and see if it works. If it works > good - the problem is the mic/mic wire/connector. If it does not and you > still have RFI - walk away for a while and cool down. > > Just a few simple steps that would apply to any radio in a similar > situation. > > Bill W2BLC K-Line > > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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Gee whiz -- I go into the hospital for a week and thing go WAY off the
rails! Thanks to W4TV and W3FPR for intelligently moving the discussion back on track. Questions: EXACTLY what is the configuration the the "vertical antenna? Quarter-wave with radials or half wave without radials? How many radials? How long? Where is the antenna feedpoint with respect to the radio? What coax are you feeding it with? Are you SURE that the connectors at both ends are properly installed and gas-pliers tight at both ends? Is there a short, fat copper bond from chassis to chassis between every piece of gear in your shack? Is there short fat copper from there to all the other grounds in your home? Joe is exactly right -- ANY "balun" that isn't multiple turns of coax around a #43 or #31 ferrite core is USELESS at HF. Those "string of beads" "baluns" sold by various vendors are badly misguided copies of the W2DU design, which what a very good design that used a LOT of #73 beads. Joe is also exactly right -- the ONLY proper connection of a cable shield is to the SHIELDING ENCLOSURE of the equipment it feeds. The cable shield should ALSO be bonded to the shielding of the microphone. Some fundamentals: ANY antenna that "works" will put RF in the shack -- it does that by radiating RF. An antenna that lacks an effective common mode choke will ALSO put RF onto the feedline. Summary of suggestions/comments: Answer the questions I asked above. They are all important. Download and STUDY k9yc/com/RFI-Ham.pdf and http://k9yc.com/GroundingAndAudio.pdf Follow these instructions carefully. I suspect that the cause of Jan's problem is failure to properly connect cable shields, and/or to bond all the gear together. 73, Jim K9YC On Tue,11/24/2015 6:54 AM, Joe Subich, W4TV wrote: > Not true ... the Icom uses an electret mic, not the dynamic Audio- > Technica. If the microphone is wired correctly, the issue is in > the antenna system and probably requires improved common mode > decoupling. Air wound solenoidal chokes are not sufficient in > the most intractable cases *like elevated verticals*. > > Replace the elevated vertical with a dummy load. If the RFI is > eliminated, the problem is in the antenna system. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by Jan Ditzian
I will continue to try solutions, but they seem to be getting random.
I found my long 50-ohm coax run to the 80-meter vertical. It ends in a DX Engineering 1:1 balun with terminals. I have tried this before. I connected one of the terminals to the vertical and the other to the ground base. The result was an SWR a little lower than with the hardline, patched-together feedline, but RFI when I run power. I do not have a choke or balun on the proximal (shack) end. It is difficult to assess the radials, but I hope to get some more time tomorrow to do this. 73, Jan, KX2A ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by John Kramer
Ugly baluns are a P O O R choice. Don't waste ur time with one. Use a ferrite
choke with a min of 3k ohms resistive at freq of interest. Jim W6AIM . -------- Original message -------- From: John Kramer <[hidden email]> Date: 11/22/2015 3:38 PM (GMT-08:00) To: Jan Ditzian <[hidden email]> Cc: [hidden email] Subject: Re: [Elecraft] RFI in audio chain 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 <[hidden email]> 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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by Jan Ditzian
Uglies DON'T WORK WELL!!!!
Use ferrite Jim W6AIM . -------- Original message -------- From: Jan Ditzian <[hidden email]> Date: 11/22/2015 4:33 PM (GMT-08:00) To: [hidden email] 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 <[hidden email]> 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:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > > > > ----- > 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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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