RF into K3 via serial port?
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In my transition to Win7, I added a 2 port serial PCI card (NewEgg purchase -- Sunix 5037A) to my Dell PC. I was going to use one of these 2 ports to communicate with my K3 Utility terminal program. Very handy CW / RTTY application. Shortly after installation I made a nice contact on 30m RTTY and then moved to 80m RTTY. SURPRISE!! During TX the K3 hung in TX and only a couple of characters (if that) were ever transmitted. I was attempting to run about 70watts or so. Only by reducing power to a few watts would the RTTY transmission seemingly be successful.
The 80m antenna is resonate and very low SWR even without the KXPA100 tuner. (My K3/10 is for VHF/UHF/Microwave IF use mostly, hence the external PA/Tuner). So RF is getting back into the K3 .. odd ... nothing is "hot" in the shack at all. My workaround is to use the new serial ports for other hardware/applications and use the one serial port in the Dell Dimension 4700 for the K3 / terminal program. Things are happy that way. I may investigate and try a ferrite core on the serial cable. But I will need to get an "HF" core since all of mine are for higher freq use. I just thought this was really odd. My serial cable is "homebrew" minimum conductor cable and I don't recall if it is shielded or not. Anyone else had any similar experiences?? 73 Bill K0AWU ______________________________________________________________ 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: RF into K3 via serial port?
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Bill,
It is usually more effective to put the ferrite on the feedline. A good current choke at the antenna feedpoint, and perhaps another at the shack entry end. If the feedline runs away from the radiator at right angles and is not otherwise run in the field of the antenna, the one at the shack end is normally not needed. Of course, if the shack is in close proximity to the radiator, all bets are off because the shack is being bombarded with RF and ferrites on the various devices in the shack is the only choice. Yes, my perception is that many electronic devices (notably computer peripherals) are getting more and more susceptible to RF. 73, Don W3FPR On 4/5/2014 8:10 PM, Bill Davis wrote: > In my transition to Win7, I added a 2 port serial PCI card (NewEgg purchase -- Sunix 5037A) to my Dell PC. I was going to use one of these 2 ports to communicate with my K3 Utility terminal program. Very handy CW / RTTY application. Shortly after installation I made a nice contact on 30m RTTY and then moved to 80m RTTY. SURPRISE!! During TX the K3 hung in TX and only a couple of characters (if that) were ever transmitted. I was attempting to run about 70watts or so. Only by reducing power to a few watts would the RTTY transmission seemingly be successful. > > The 80m antenna is resonate and very low SWR even without the KXPA100 tuner. (My K3/10 is for VHF/UHF/Microwave IF use mostly, hence the external PA/Tuner). > > So RF is getting back into the K3 .. odd ... nothing is "hot" in the shack at all. My workaround is to use the new serial ports for other hardware/applications and use the one serial port in the Dell Dimension 4700 for the K3 / terminal program. Things are happy that way. > > I may investigate and try a ferrite core on the serial cable. But I will need to get an "HF" core since all of mine are for higher freq use. I just thought this was really odd. My serial cable is "homebrew" minimum conductor cable and I don't recall if it is shielded or not. > > > Anyone else had any similar experiences?? > > 73 Bill K0AWU > ______________________________________________________________ > 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: RF into K3 via serial port?
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What kind of cables are you using between the PC and the K3? If shielded, are you sure the shields are connected to the DE9 shell at both ends? The RF _could_ be getting into the conductors and causing problems in the computer/serial card and not actually the K3. The computer could then be asserting or negating the handshake lines, killing K3 transmission, or causing the software to send a stop data transmission to the K3. We have found the usually the RFI problems are outside of the K3.
Be sure to read the RFI info at K9YC’s site. It provides a lot of good details about the problems of RS-232 cabling and connections. Also, even though you may not detect “hot RF” in the shack, it just might be there. RF likes to ride on the outside of the coax going from the antenna to the radio, causing problems. Thus good choking is needed to eliminate the problems. Again, K9YC’s document has some really good info. http://www.audiosystemsgroup.com/K9YC/K9YC.htm 73! Jack B, W6FB On Apr 5, 2014, at 5:39 PM, Don Wilhelm <[hidden email]> wrote: > Bill, > > It is usually more effective to put the ferrite on the feedline. A good current choke at the antenna feedpoint, and perhaps another at the shack entry end. > If the feedline runs away from the radiator at right angles and is not otherwise run in the field of the antenna, the one at the shack end is normally not needed. > > Of course, if the shack is in close proximity to the radiator, all bets are off because the shack is being bombarded with RF and ferrites on the various devices in the shack is the only choice. > > Yes, my perception is that many electronic devices (notably computer peripherals) are getting more and more susceptible to RF. > > 73, > Don W3FPR > > On 4/5/2014 8:10 PM, Bill Davis wrote: >> In my transition to Win7, I added a 2 port serial PCI card (NewEgg purchase -- Sunix 5037A) to my Dell PC. I was going to use one of these 2 ports to communicate with my K3 Utility terminal program. Very handy CW / RTTY application. Shortly after installation I made a nice contact on 30m RTTY and then moved to 80m RTTY. SURPRISE!! During TX the K3 hung in TX and only a couple of characters (if that) were ever transmitted. I was attempting to run about 70watts or so. Only by reducing power to a few watts would the RTTY transmission seemingly be successful. >> >> The 80m antenna is resonate and very low SWR even without the KXPA100 tuner. (My K3/10 is for VHF/UHF/Microwave IF use mostly, hence the external PA/Tuner). >> >> So RF is getting back into the K3 .. odd ... nothing is "hot" in the shack at all. My workaround is to use the new serial ports for other hardware/applications and use the one serial port in the Dell Dimension 4700 for the K3 / terminal program. Things are happy that way. >> >> I may investigate and try a ferrite core on the serial cable. But I will need to get an "HF" core since all of mine are for higher freq use. I just thought this was really odd. My serial cable is "homebrew" minimum conductor cable and I don't recall if it is shielded or not. >> >> >> Anyone else had any similar experiences?? >> >> 73 Bill K0AWU >> ______________________________________________________________ >> 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] |
Re: RF into K3 via serial port?
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In reply to this post by Bill Davis
Hi Bill,
I've had RF problems with powered speakers and with USB. In my case, the antenna is more than 50 feet from the shack location. Some RF was getting into the speaker input or circuitry anyway. Since it also got into the USB, I also isolated the computer. The antenna is not resonant except on 80m, so there is some amount of RF on the feedline even though it's isolated using a BL-2 balun before a transition to 450 ohm ladder line. That transition point is about 12 feet from the shack. Using a few Laird Technologies toroid cores solved the problem. In case it matters, I used cores that are most effective at 5-10 MHz and large enough to put 4-5 turns on each core. This gives a few hundred ohms of isolation. The Laird cores I used were Laird part number LFB360230-300. You can buy these through Digikey using their part number 240-2287-ND. 73, matt W6NIA On Sat, 5 Apr 2014 17:10:01 -0700 (PDT), you wrote: > In my transition to Win7, I added a 2 port serial PCI card (NewEgg purchase -- Sunix 5037A) to my Dell PC. I was going to use one of these 2 ports to communicate with my K3 Utility terminal program. Very handy CW / RTTY application. Shortly after installation I made a nice contact on 30m RTTY and then moved to 80m RTTY. SURPRISE!! During TX the K3 hung in TX and only a couple of characters (if that) were ever transmitted. I was attempting to run about 70watts or so. Only by reducing power to a few watts would the RTTY transmission seemingly be successful. > > The 80m antenna is resonate and very low SWR even without the KXPA100 tuner. (My K3/10 is for VHF/UHF/Microwave IF use mostly, hence the external PA/Tuner). > > So RF is getting back into the K3 .. odd ... nothing is "hot" in the shack at all. My workaround is to use the new serial ports for other hardware/applications and use the one serial port in the Dell Dimension 4700 for the K3 / terminal program. Things are happy that way. > > I may investigate and try a ferrite core on the serial cable. But I will need to get an "HF" core since all of mine are for higher freq use. I just thought this was really odd. My serial cable is "homebrew" minimum conductor cable and I don't recall if it is shielded or not. > > > Anyone else had any similar experiences?? > >73 Bill K0AWU >______________________________________________________________ >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] -- "Give me six hours to chop down a tree and I will spend the first four sharpening the axe." -A. Lincoln ______________________________________________________________ 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 Jack Brindle-2
Ditto on the K9YC info.
I have an resonant 80m dipole strung right over the house at about 60'. I was getting RF on nearly everything in the shack. Two of the K9YC chokes wound 5 turns of RG-213 through a stack of 5 Mix 31 toroids, one at the feed and one at the entrance knocked it back by 90% with only the computer being left. The secret to getting it gone from the computer was the idea of using CAT5/6 twisted pair networking cable for all computer connections. Especially the serial ports I installed in my home brew computers. The rest of the house was relatively easy and as it turns out the LCD/LED TV's were the easiest. On 4/5/2014 7:57 PM, Jack Brindle wrote: > What kind of cables are you using between the PC and the K3? If shielded, are you sure the shields are connected to the DE9 shell at both ends? The RF _could_ be getting into the conductors and causing problems in the computer/serial card and not actually the K3. The computer could then be asserting or negating the handshake lines, killing K3 transmission, or causing the software to send a stop data transmission to the K3. We have found the usually the RFI problems are outside of the K3. > > Be sure to read the RFI info at K9YC’s site. It provides a lot of good details about the problems of RS-232 cabling and connections. Also, even though you may not detect “hot RF” in the shack, it just might be there. RF likes to ride on the outside of the coax going from the antenna to the radio, causing problems. Thus good choking is needed to eliminate the problems. Again, K9YC’s document has some really good info. > > http://www.audiosystemsgroup.com/K9YC/K9YC.htm > > 73! > > Jack B, W6FB -- R. Kevin Stover AC0H ARRL FISTS #11993 SKCC #215 NAQCC #3441 ______________________________________________________________ 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 Don Wilhelm-4
On 4/5/2014 5:39 PM, Don Wilhelm wrote:
> It is usually more effective to put the ferrite on the feedline. A choke on the feedline at the feedpoint is certainly a good idea, but I suspect the problem is the serial cable. I had exactly the same problem in Chicago 10 years ago, and found the cause -- the serial cable was parallel wires, not twisted pair. I solved it by building a serial cable using CAT5, as shown in the Power Point on Ham Interfacing on my website. The better address is k9yc.com/publish.htm 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 Bill Davis
Dear Bill,
I too have had (have) something of the same problem. For a long time I could transmit 20 W only on digital modes on 80 meters. If transmitting more power the K3 would lock in transmit mode and I would have to turn it off to stop it transmitting. Now I have bought a pair of Line In Line Out cables with very good shielding. I can now transmit at least 250 W without locking the K3 in transmit mode. My next problem is that when using Ham Radio deluxe (HRD) to control the K3 the HRD locks up so I have to close the program and start again if I want to do any changes in frequency, power or whatever. Other programs running on the computer at the same time do not lock up. So my guess is that it is my COM port that locks up. I may try using some better shielded cable for the COM port. I haven't had the time yet. Best regards OZ1CCM Kjeld -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Bill Davis Sent: 6. april 2014 02:10 To: Elecraft Mailer Subject: [Elecraft] RF into K3 via serial port? In my transition to Win7, I added a 2 port serial PCI card (NewEgg purchase -- Sunix 5037A) to my Dell PC. I was going to use one of these 2 ports to communicate with my K3 Utility terminal program. Very handy CW / RTTY application. Shortly after installation I made a nice contact on 30m RTTY and then moved to 80m RTTY. SURPRISE!! During TX the K3 hung in TX and only a couple of characters (if that) were ever transmitted. I was attempting to run about 70watts or so. Only by reducing power to a few watts would the RTTY transmission seemingly be successful. The 80m antenna is resonate and very low SWR even without the KXPA100 tuner. (My K3/10 is for VHF/UHF/Microwave IF use mostly, hence the external PA/Tuner). So RF is getting back into the K3 .. odd ... nothing is "hot" in the shack at all. My workaround is to use the new serial ports for other hardware/applications and use the one serial port in the Dell Dimension 4700 for the K3 / terminal program. Things are happy that way. I may investigate and try a ferrite core on the serial cable. But I will need to get an "HF" core since all of mine are for higher freq use. I just thought this was really odd. My serial cable is "homebrew" minimum conductor cable and I don't recall if it is shielded or not. Anyone else had any similar experiences?? 73 Bill K0AWU ______________________________________________________________ Elecraft mailing list Home: <http://mailman.qth.net/mailman/listinfo/elecraft> http://mailman.qth.net/mailman/listinfo/elecraft Help: <http://mailman.qth.net/mmfaq.htm> http://mailman.qth.net/mmfaq.htm Post: <mailto:[hidden email]> mailto:[hidden email] This list hosted by: <http://www.qsl.net> http://www.qsl.net Please help support this email list: <http://www.qsl.net/donate.html> http://www.qsl.net/donate.html Message delivered to <mailto:[hidden email]> [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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