Audio Hum in TX Data Mode
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I put up a new 6m antenna mainly for EME and I was so looking forward to using my K3S. The RX is great, I run it in parallel with 2 other receivers and it works very well on EME. However try as I might I cannot get rid of some quite bad hum on the TX Audio. I am using USB and before you ask yes I have got a low impedance ground from the PC to the K3S although removing it makes absolutely no difference. What did make a difference was moving the radio away from sources of magnetic fields such as monitors. However I cannot get rid of it completely. It also increases or at least changes when I put my hands on the radio.
I have a few other radios located nearby and close to a monitor, pc or PSU and they do not suffer from this at all. Is this a common problem, is it a bad ground in the audio path internally or magnetic coupling into an audio transformer? It is completely impractical for me to move my radios 10 feet from any magnetic fields. Short of wrapping the radio in mu metal I really do not seem to be able to fix this. Any ideas? I have read and understood and followed Jim K9YC's advice and this works perfectly for my other 3 radios. I am really at a loss. 73 Conrad PA5Y ______________________________________________________________ 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 can buy an audio isolator cable on line to remove the ground loop issues. Just search the topic for devices. I believe I used Amazon.
Bill 920-421-1172 ________________________________ From: [hidden email] <[hidden email]> on behalf of Conrad PA5Y <[hidden email]> Sent: Friday, September 27, 2019 4:26:55 PM To: [hidden email] <[hidden email]> Subject: [Elecraft] Audio Hum in TX Data Mode I put up a new 6m antenna mainly for EME and I was so looking forward to using my K3S. The RX is great, I run it in parallel with 2 other receivers and it works very well on EME. However try as I might I cannot get rid of some quite bad hum on the TX Audio. I am using USB and before you ask yes I have got a low impedance ground from the PC to the K3S although removing it makes absolutely no difference. What did make a difference was moving the radio away from sources of magnetic fields such as monitors. However I cannot get rid of it completely. It also increases or at least changes when I put my hands on the radio. I have a few other radios located nearby and close to a monitor, pc or PSU and they do not suffer from this at all. Is this a common problem, is it a bad ground in the audio path internally or magnetic coupling into an audio transformer? It is completely impractical for me to move my radios 10 feet from any magnetic fields. Short of wrapping the radio in mu metal I really do not seem to be able to fix this. Any ideas? I have read and understood and followed Jim K9YC's advice and this works perfectly for my other 3 radios. I am really at a loss. 73 Conrad PA5Y ______________________________________________________________ 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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Do you hear the human SSB also?
> On Sep 27, 2019, at 8:20 PM, Bill Johnson <[hidden email]> wrote: > You can buy an audio isolator cable on line to remove the ground loop issues. Just search the topic for devices. I believe I used Amazon. Bill 920-421-1172 ________________________________ From: [hidden email] <[hidden email]> on behalf of Conrad PA5Y <[hidden email]> Sent: Friday, September 27, 2019 4:26:55 PM To: [hidden email] <[hidden email]> Subject: [Elecraft] Audio Hum in TX Data Mode I put up a new 6m antenna mainly for EME and I was so looking forward to using my K3S. The RX is great, I run it in parallel with 2 other receivers and it works very well on EME. However try as I might I cannot get rid of some quite bad hum on the TX Audio. I am using USB and before you ask yes I have got a low impedance ground from the PC to the K3S although removing it makes absolutely no difference. What did make a difference was moving the radio away from sources of magnetic fields such as monitors. However I cannot get rid of it completely. It also increases or at least changes when I put my hands on the radio. I have a few other radios located nearby and close to a monitor, pc or PSU and they do not suffer from this at all. Is this a common problem, is it a bad ground in the audio path internally or magnetic coupling into an audio transformer? It is completely impractical for me to move my radios 10 feet from any magnetic fields. Short of wrapping the radio in mu metal I really do not seem to be able to fix this. Any ideas? I have read and understood and followed Jim K9YC's advice and this works perfectly for my other 3 radios. I am really at a loss. 73 Conrad PA5Y ______________________________________________________________ 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 Conrad PA5Y
Conrad,
Can you turn off the other devices around your rig to see if any of them are creating the problem? I had a small portable electric heater that created hum in my K3S when plugged into the same outlet. Running the heater on an extension cord to an outlet across the room fixed the problem. Have you measured the AC ripple on the output of your DC power supply when you are key down? ____________ 73, Jim - N4ST -----Original Message----- From: [hidden email] <[hidden email]> On Behalf Of Conrad PA5Y Sent: Friday, September 27, 2019 17:27 To: [hidden email] Subject: [Elecraft] Audio Hum in TX Data Mode I put up a new 6m antenna mainly for EME and I was so looking forward to using my K3S. The RX is great, I run it in parallel with 2 other receivers and it works very well on EME. However try as I might I cannot get rid of some quite bad hum on the TX Audio. I am using USB and before you ask yes I have got a low impedance ground from the PC to the K3S although removing it makes absolutely no difference. What did make a difference was moving the radio away from sources of magnetic fields such as monitors. However I cannot get rid of it completely. It also increases or at least changes when I put my hands on the radio. I have a few other radios located nearby and close to a monitor, pc or PSU and they do not suffer from this at all. Is this a common problem, is it a bad ground in the audio path internally or magnetic coupling into an audio transformer? It is completely impractical for me to move my radios 10 feet from any magnetic fields. Short of wrapping the radio in mu metal I really do not seem to be able to fix this. Any ideas? I have read and understood and followed Jim K9YC's advice and this works perfectly for my other 3 radios. I am really at a loss. 73 Conrad PA5Y ______________________________________________________________ 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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That is a great idea unless you have my station... I have 4 computers, and tons of other stuff. Tried to isolate the issue and decided on the opto isolator as the simplest and time saving fix.
73, Bill K9YEQ https://wrj-tech.com/ -----Original Message----- From: [hidden email] <[hidden email]> On Behalf Of Jim - N4ST Sent: Friday, September 27, 2019 7:43 PM To: 'Conrad PA5Y' <[hidden email]>; [hidden email] Subject: Re: [Elecraft] Audio Hum in TX Data Mode Conrad, Can you turn off the other devices around your rig to see if any of them are creating the problem? I had a small portable electric heater that created hum in my K3S when plugged into the same outlet. Running the heater on an extension cord to an outlet across the room fixed the problem. Have you measured the AC ripple on the output of your DC power supply when you are key down? ____________ 73, Jim - N4ST -----Original Message----- From: [hidden email] <[hidden email]> On Behalf Of Conrad PA5Y Sent: Friday, September 27, 2019 17:27 To: [hidden email] Subject: [Elecraft] Audio Hum in TX Data Mode I put up a new 6m antenna mainly for EME and I was so looking forward to using my K3S. The RX is great, I run it in parallel with 2 other receivers and it works very well on EME. However try as I might I cannot get rid of some quite bad hum on the TX Audio. I am using USB and before you ask yes I have got a low impedance ground from the PC to the K3S although removing it makes absolutely no difference. What did make a difference was moving the radio away from sources of magnetic fields such as monitors. However I cannot get rid of it completely. It also increases or at least changes when I put my hands on the radio. I have a few other radios located nearby and close to a monitor, pc or PSU and they do not suffer from this at all. Is this a common problem, is it a bad ground in the audio path internally or magnetic coupling into an audio transformer? It is completely impractical for me to move my radios 10 feet from any magnetic fields. Short of wrapping the radio in mu metal I really do not seem to be able to fix this. Any ideas? I have read and understood and followed Jim K9YC's advice and this works perfectly for my other 3 radios. I am really at a loss. 73 Conrad PA5Y ______________________________________________________________ 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 Conrad PA5Y
On 9/27/2019 2:26 PM, Conrad PA5Y wrote:
> What did make a difference was moving the radio away from sources of magnetic fields such as monitors. First, an important clarification -- is it HUM (pure 50 Hz) or BUZZ (harmonics of 50 Hz)? You description sounds like hum. The important thing is that the causes are different. Hum is, indeed, magnetic coupling of the 50 Hz field to some loop in the audio wiring. Magnetic coupling is proportional to the area of the loop. Suggestions. First, get power for all interconnected equipment from outlets that share the same protective earth. Second, bond chassis-chassis of every piece of equipment in the audio interconnection path. Third, try to figure out what the loop is that is doing the coupling and reduce its area. In some recording studios where a strong magnetic field exists, the solution is to run shielded twisted pair audio wiring in close proximity to power wiring. Also try to find or eliminate the source of the magnetic field. In North America, neutral must be bonded to earth at one, and ONLY one point, usually where it enters a building. A second bond between neutral and the same protective earth can create a magnetic field. Is it possible that there is a second bond somewhere in your system, perhaps associated with power to your EME setup? The I/O board for the original K3 uses un-shielded audio transformers that are a sitting duck for magnetic fields. My neighbor K6XX is an engineer at Elecraft. When he was testing an early K3 prototype, he set it up almost on top of his 1.5 kW power amp. When he tried to run RTTY, The AF circuitry was set into regeneration by the 60 Hz field! The solution I suggested was a steep high pass filter for AFSK-A, and that solved it. Many years ago, a Chicago FM station whose engineers I knew well moved their studios from a location downtown to another location that is common to a TV studio with whom they had a relationship. When they first moved in, a strong magnetic field was coupling into the mic input transformers of their music mixing desks. The cause was an error in mains wiring -- the neutral for the distribution panel for the FM studio was exchanged with the neutral for a distribution panel feeding lighting in a different part of the building. 73, Jim K9YC ______________________________________________________________ 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 Conrad PA5Y
Good morning Conrad,
do you have the possibility to check the signal on an SDR or spectrum analyzer with sufficient resolution. That might be helpful to determine the origin of the noise and hence countermeasures. 73/Roger, DL5RBW -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Conrad PA5Y Sent: Friday, September 27, 2019 11:27 PM To: [hidden email] Subject: [Elecraft] Audio Hum in TX Data Mode I put up a new 6m antenna mainly for EME and I was so looking forward to using my K3S. The RX is great, I run it in parallel with 2 other receivers and it works very well on EME. However try as I might I cannot get rid of some quite bad hum on the TX Audio. I am using USB and before you ask yes I have got a low impedance ground from the PC to the K3S although removing it makes absolutely no difference. What did make a difference was moving the radio away from sources of magnetic fields such as monitors. However I cannot get rid of it completely. It also increases or at least changes when I put my hands on the radio. I have a few other radios located nearby and close to a monitor, pc or PSU and they do not suffer from this at all. Is this a common problem, is it a bad ground in the audio path internally or magnetic coupling into an audio transformer? It is completely impractical for me to move my radios 10 feet from any magnetic fields. Short of wrapping the radio in mu metal I really do not seem to be able to fix this. Any ideas? I have read and understood and followed Jim K9YC's advice and this works perfectly for my other 3 radios. I am really at a loss. 73 Conrad PA5Y ______________________________________________________________ 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] |
Re: Audio Hum in TX Data Mode
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Conrad,
I had the same problem a few years ago when I placed my Alpha 9500 on the left side of my K3S. After much perturbation, I finally figured what the issue was. The power supply for the Alpha 9500 is on the right side of the Amp, and the isolation transformers for the line in and line out are on the left side of the K3 (K3S). When in such proximity, the magnetic fields interact, and induce hum when using line in on the Elecraft radios. My solution ended up being easy. The transformer in my Alpha was an old type, and I was able to switch it out with the new model with (I think) is a toroidal core, and that solved the problem. Dick, K8ZTT I put up a new 6m antenna mainly for EME and I was so looking forward to using my K3S. The RX is great, I run it in parallel with 2 other receivers and it works very well on EME. However try as I might I cannot get rid of some quite bad hum on the TX Audio. I am using USB and before you ask yes I have got a low impedance ground from the PC to the K3S although removing it makes absolutely no difference. What did make a difference was moving the radio away from sources of magnetic fields such as monitors. However I cannot get rid of it completely. It also increases or at least changes when I put my hands on the radio. I have a few other radios located nearby and close to a monitor, pc or PSU and they do not suffer from this at all. Is this a common problem, is it a bad ground in the audio path internally or magnetic coupling into an audio transformer? It is completely impractical for me to move my radios 10 feet from any magnetic fields. Short of wrapping the radio in mu metal I really do not seem to be able to fix this. Any ideas? I have read and understood and followed Jim K9YC's advice and this works perfectly for my other 3 radios. I am really at a loss. 73 Conrad PA5Y ______________________________________________________________ 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 Jim Miller
Their isolators built in the K3 on the LineIn/LineOut lines.
And there is no “tx DATA” mode. The “tx” is indicates which VFO is used for transmit with an arrow above (A) or below (B). Sent from my iPhone ...nr4c. bill > On Sep 27, 2019, at 8:25 PM, Jim Miller <[hidden email]> wrote: > > Do you hear the human SSB also? > > >> On Sep 27, 2019, at 8:20 PM, Bill Johnson <[hidden email]> wrote: >> > > You can buy an audio isolator cable on line to remove the ground loop issues. Just search the topic for devices. I believe I used Amazon. > > Bill > 920-421-1172 > > ________________________________ > From: [hidden email] <[hidden email]> on behalf of Conrad PA5Y <[hidden email]> > Sent: Friday, September 27, 2019 4:26:55 PM > To: [hidden email] <[hidden email]> > Subject: [Elecraft] Audio Hum in TX Data Mode > > I put up a new 6m antenna mainly for EME and I was so looking forward to using my K3S. The RX is great, I run it in parallel with 2 other receivers and it works very well on EME. However try as I might I cannot get rid of some quite bad hum on the TX Audio. I am using USB and before you ask yes I have got a low impedance ground from the PC to the K3S although removing it makes absolutely no difference. What did make a difference was moving the radio away from sources of magnetic fields such as monitors. However I cannot get rid of it completely. It also increases or at least changes when I put my hands on the radio. > > I have a few other radios located nearby and close to a monitor, pc or PSU and they do not suffer from this at all. Is this a common problem, is it a bad ground in the audio path internally or magnetic coupling into an audio transformer? > > It is completely impractical for me to move my radios 10 feet from any magnetic fields. Short of wrapping the radio in mu metal I really do not seem to be able to fix this. > > Any ideas? I have read and understood and followed Jim K9YC's advice and this works perfectly for my other 3 radios. I am really at a loss. > > 73 > > Conrad PA5Y > ______________________________________________________________ > 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] ______________________________________________________________ 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 Elecraft mailing list
I had a similar issue with a TenTec power supply next to a TenTec transceiver. The solution was to move the power supply.
Chuck Jack Hawley KE9UW Sent from my iPhone, cjack > On Sep 28, 2019, at 12:35 PM, RIchard Williams via Elecraft <[hidden email]> wrote: > > Conrad, > I had the same problem a few years ago when I placed my Alpha 9500 on the left side of my K3S. After much perturbation, I finally figured what the issue was. The power supply for the Alpha 9500 is on the right side of the Amp, and the isolation transformers for the line in and line out are on the left side of the K3 (K3S). When in such proximity, the magnetic fields interact, and induce hum when using line in on the Elecraft radios. My solution ended up being easy. The transformer in my Alpha was an old type, and I was able to switch it out with the new model with (I think) is a toroidal core, and that solved the problem. > Dick, K8ZTT > > > > > > > > > > I put up a new 6m antenna mainly for EME and I was so looking forward to > using my K3S. The RX is great, I run it in parallel with 2 other receivers > and it works very well on EME. However try as I might I cannot get rid of > some quite bad hum on the TX Audio. I am using USB and before you ask yes I > have got a low impedance ground from the PC to the K3S although removing it > makes absolutely no difference. What did make a difference was moving the > radio away from sources of magnetic fields such as monitors. However I > cannot get rid of it completely. It also increases or at least changes when > I put my hands on the radio. > > I have a few other radios located nearby and close to a monitor, pc or PSU > and they do not suffer from this at all. Is this a common problem, is it a > bad ground in the audio path internally or magnetic coupling into an audio > transformer? > > It is completely impractical for me to move my radios 10 feet from any > magnetic fields. Short of wrapping the radio in mu metal I really do not > seem to be able to fix this. > > Any ideas? I have read and understood and followed Jim K9YC's advice and > this works perfectly for my other 3 radios. I am really at a loss. > > 73 > > Conrad PA5Y > ______________________________________________________________ > 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] 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]
Chuck, KE9UW
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