Re: [Elecraft] Data transmission on 30 meters with PX3 problem
On 9/2/2018 6:28 PM, Bill Frantz wrote: This is one of the clearest explanations I have seen of the issue. Thanks Erik. I guess you never saw mine, upon which Erik's is based. I first published this in 2005! 73, Jim K9YC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Data transmission on 30 meters with PX3 problem
Here is another good information source on baluns and specifically the type of material and how it performs under various conditions. http://www.karinya.net/g3txq/chokes/ As it is said "I have no dog in this fight". 73 Bob, K4TAX On 9/2/2018 8:28 PM, Bill Frantz wrote: This is one of the clearest explanations I have seen of the issue. Thanks Erik. 73 Bill AE6JV On 9/2/18 at 5:53 PM, ebasil...@cox.net (Erik Basilier) wrote: As Jim K9YC has pointed out in his writeup on baluns etc, there is a threshold effect when one applies a choke to reduce common mode current. The current is determined by driving voltage and total (complex) series impedance. The choke RF impedance will have a reactive as well as a resistive component, and so does the circuit before the choke is applied. The reactances may be of opposite signs and cancel out, in which case adding the choke may actually make it easier for the common mode current to flow. It is easy to think that one can add a marginal choke and look for a small improvement as a reliable indication that a good choke will be worth the investment or not. Wrong! Only then the choke tried has high enough impedance to dominate the circuit can one judge whether whether adding chokes helps. Also, adding the perfect choke near the antenna feed point is not likely completely to eliminate common mode RF current at the rig end of the cable. For common mode purposes, the perfect choke acts effectively to disconnect the outside of the coax from the antenna, but that metal is still there, close to the antenna, and it will be part of the antenna system as a parasitic antenna element, affect the radiation pattern, and carry substantial RF current. 73, Erik K7TV --- Bill Frantz| There's nothing so clear as | Periwinkle (408)356-8506 | a design you haven't written | 16345 Englewood Ave www.pwpconsult.com | down.- Dean Tribble | Los Gatos, CA 95032 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to rmcg...@blomand.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Data transmission on 30 meters with PX3 problem
This is one of the clearest explanations I have seen of the issue. Thanks Erik. 73 Bill AE6JV On 9/2/18 at 5:53 PM, ebasil...@cox.net (Erik Basilier) wrote: > As Jim K9YC has pointed out in his writeup on baluns etc, there is a > threshold effect when one applies a choke to reduce common mode current. The > current is determined by driving voltage and total (complex) series > impedance. The choke RF impedance will have a reactive as well as a > resistive component, and so does the circuit before the choke is applied. > The reactances may be of opposite signs and cancel out, in which case adding > the choke may actually make it easier for the common mode current to flow. > It is easy to think that one can add a marginal choke and look for a small > improvement as a reliable indication that a good choke will be worth the > investment or not. Wrong! Only then the choke tried has high enough > impedance to dominate the circuit can one judge whether whether adding > chokes helps. Also, adding the perfect choke near the antenna feed point is > not likely completely to eliminate common mode RF current at the rig end of > the cable. For common mode purposes, the perfect choke acts effectively to > disconnect the outside of the coax from the antenna, but that metal is still > there, close to the antenna, and it will be part of the antenna system as a > parasitic antenna element, affect the radiation pattern, and carry > substantial RF current. > 73, > Erik K7TV --- Bill Frantz| There's nothing so clear as | Periwinkle (408)356-8506 | a design you haven't written | 16345 Englewood Ave www.pwpconsult.com | down.- Dean Tribble | Los Gatos, CA 95032 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
[Elecraft] Data transmission on 30 meters with PX3 problem
As Jim K9YC has pointed out in his writeup on baluns etc, there is a threshold effect when one applies a choke to reduce common mode current. The current is determined by driving voltage and total (complex) series impedance. The choke RF impedance will have a reactive as well as a resistive component, and so does the circuit before the choke is applied. The reactances may be of opposite signs and cancel out, in which case adding the choke may actually make it easier for the common mode current to flow. It is easy to think that one can add a marginal choke and look for a small improvement as a reliable indication that a good choke will be worth the investment or not. Wrong! Only then the choke tried has high enough impedance to dominate the circuit can one judge whether whether adding chokes helps. Also, adding the perfect choke near the antenna feed point is not likely completely to eliminate common mode RF current at the rig end of the cable. For common mode purposes, the perfect choke acts effectively to disconnect the outside of the coax from the antenna, but that metal is still there, close to the antenna, and it will be part of the antenna system as a parasitic antenna element, affect the radiation pattern, and carry substantial RF current. 73, Erik K7TV __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Data transmission on 30 meters with PX3 problem
Back in my early days as a ham (1950s), I inadvertently discovered that the metal housing of a D104 microphone was very effective in performing such a touch test. Bob, N7XY On 9/2/18 7:19 AM, John Oppenheimer wrote: On 09/02/2018 07:56 AM, Don Wilhelm wrote: That W3EDP antenna is a strong suspect, as is any off-center fed antenna or end fed antenna. They can produce large amounts of RF in the shack. Hi Gwen, Don is correct. The W3EDP with a large choke Balun, as pictured, between the Unun and KX3 is an OCF Doublet with a resonant frequency of 11 MHz. It is rather difficult, if not impossible, to isolate a dipole end impedance using a choke Balun. The KX3, being at the high impedance point on 30 meters, will experience a rather high RF voltage. A way to determine if the rig is part of the antenna is to use what I call a "touch test." Observe SWR while transmitting, if touching the KX3 antenna BNC jack causes the SWR to change, then the KX3 is part of the antenna. At the extreme, the touch results with a RF burn. I have experience RF burn at 15 watts. John KN5L __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to n...@n7xy.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Data transmission on 30 meters with PX3 problem
On 9/2/2018 7:39 AM, Martin wrote: FT 140-43 cores will do. For higher power, use FT 240-43. #43 material is only good above about 10 MHz. 73, Jim K9YC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Data transmission on 30 meters with PX3 problem
You might want to add a common mode choke. Look here : http://www.dg0sa.de/balun1zu4kleinptfe.pdf It is in german, but the pictures show how easy it is to do. First, the choke is shown. The second core is the 4:1 transformer which you already have. FT 140-43 cores will do. For higher power, use FT 240-43. Connect : TRX->choke->Transformer->antenna. -- 73, Martin Ohne CW ist es nur CB... __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Data transmission on 30 meters with PX3 problem
On 09/02/2018 07:56 AM, Don Wilhelm wrote: > That W3EDP antenna is a strong suspect, as is any off-center fed antenna > or end fed antenna. They can produce large amounts of RF in the shack. Hi Gwen, Don is correct. The W3EDP with a large choke Balun, as pictured, between the Unun and KX3 is an OCF Doublet with a resonant frequency of 11 MHz. It is rather difficult, if not impossible, to isolate a dipole end impedance using a choke Balun. The KX3, being at the high impedance point on 30 meters, will experience a rather high RF voltage. A way to determine if the rig is part of the antenna is to use what I call a "touch test." Observe SWR while transmitting, if touching the KX3 antenna BNC jack causes the SWR to change, then the KX3 is part of the antenna. At the extreme, the touch results with a RF burn. I have experience RF burn at 15 watts. John KN5L __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Data transmission on 30 meters with PX3 problem
Gwen, First of all, a T200-2 is an iron core toroid, not ferrite, and is not likely to prevent much RF noise coupling. Any ferrite core will have an FTxxx diameter designation with two digits after the hyphen. That W3EDP antenna is a strong suspect, as is any off-center fed antenna or end fed antenna. They can produce large amounts of RF in the shack. Install a GOOD current mode choke near the antenna feedpoint. One of the best is a stack of 4 or 5 FT240-31 with the coax wound for 4 or 5 turns through the center. That should be placed close to the antenna end of the coax - exception, an end-fed antenna may need to use a part of the coax as a counterpoise (which is why a minimum length of coax is specified for them) - put the choke that minimum length away from the antenna. 73, Don W3FPR On 9/1/2018 11:00 PM, Gwen Patton wrote: This happens very rarely for me EXCEPT for 30 meters. Then it happens so much, it makes data modes (CW, RTTY, PSK) useless. I'm using a wired USB keyboard connected to the PX3. If I'm on 30 meters, and I use the ATU to match the antenna, transmitting any data mode causes extra, spurious characters to be added onto the end of the keyboard input buffer. In some circumstances, it starts appending additional messages stored in message slots mapped to function keys. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Data transmission on 30 meters with PX3 problem
Hi Gwen, Still sounds like RF getting in somewhere. That kind of antenna is guaranteed to bring common mode current into the shack. If you have a dummy load I would connect it directly to the output of the radio and see if the problem still occurs. 73, Gary K9GS Original message From: Gwen Patton Date: 9/1/18 10:00 PM (GMT-06:00) To: elecraft@mailman.qth.net Subject: [Elecraft] Data transmission on 30 meters with PX3 problem This happens very rarely for me EXCEPT for 30 meters. Then it happens so much, it makes data modes (CW, RTTY, PSK) useless. I'm using a wired USB keyboard connected to the PX3. If I'm on 30 meters, and I use the ATU to match the antenna, transmitting any data mode causes extra, spurious characters to be added onto the end of the keyboard input buffer. In some circumstances, it starts appending additional messages stored in message slots mapped to function keys. Usually it's just a few characters -- a couple of numbers, a few alphas -- that get transmitted at the end of my transmission. In less frequent cases, the transmission doesn't stop, as new characters are being shoved into the keyboard buffer faster than they can be transmitted. Pressing backspace to erase these characters works very seldom, though it can help, marginally. In very rare cases, it seems scan codes for function keys are getting shoved into the keyboard buffer, which appends those message slot contents to the end. I usually wind up hitting ESC to stop the transmission, because it's running wild. RF power isn't a determinant. I can run power down to less than a watt and it still happens. I tried wrapping a big ferrite toroid (T200-2) with the keyboard cable just before the PX3 keyboard port, but it doesn't appear to help. I've searched for solutions online and in both the PX3 and KX3 manuals. The antenna is a half-length "W3EDP Jr." end-fed antenna with an LDG RU-4:1 unun, run from my front porch to a tree, about 15' up at the porch end, and about 25' up at the far end. This is the antenna I'm using: https://thewakesileave.wordpress.com/2016/08/15/a-42-portable-multiband-hf-antenna-with-no-wire-on-the-ground-the-w3edp-jr/ Has anyone else had this problem, or can you suggest something I might set differently in a menu option? I've gone through about everything I can think of, including changing the position of the coax, the aforementioned choke on the keyboard cable, et. al., but can't figure out what's causing this. It acts like RF getting into the keyboard. I'll try a different keyboard while I wait for any suggestions, but other than that, I'm stuck. Being a member of 30MDG, I'd sort of like to be able to operate on 30! 73, Gwen NG3P -- -+-+-+-+- Jenny Everywhere's Infinite: Quark Time http://quarktime.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to garyk...@wi.rr.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
[Elecraft] Data transmission on 30 meters with PX3 problem
This happens very rarely for me EXCEPT for 30 meters. Then it happens so much, it makes data modes (CW, RTTY, PSK) useless. I'm using a wired USB keyboard connected to the PX3. If I'm on 30 meters, and I use the ATU to match the antenna, transmitting any data mode causes extra, spurious characters to be added onto the end of the keyboard input buffer. In some circumstances, it starts appending additional messages stored in message slots mapped to function keys. Usually it's just a few characters -- a couple of numbers, a few alphas -- that get transmitted at the end of my transmission. In less frequent cases, the transmission doesn't stop, as new characters are being shoved into the keyboard buffer faster than they can be transmitted. Pressing backspace to erase these characters works very seldom, though it can help, marginally. In very rare cases, it seems scan codes for function keys are getting shoved into the keyboard buffer, which appends those message slot contents to the end. I usually wind up hitting ESC to stop the transmission, because it's running wild. RF power isn't a determinant. I can run power down to less than a watt and it still happens. I tried wrapping a big ferrite toroid (T200-2) with the keyboard cable just before the PX3 keyboard port, but it doesn't appear to help. I've searched for solutions online and in both the PX3 and KX3 manuals. The antenna is a half-length "W3EDP Jr." end-fed antenna with an LDG RU-4:1 unun, run from my front porch to a tree, about 15' up at the porch end, and about 25' up at the far end. This is the antenna I'm using: https://thewakesileave.wordpress.com/2016/08/15/a-42-portable-multiband-hf-antenna-with-no-wire-on-the-ground-the-w3edp-jr/ Has anyone else had this problem, or can you suggest something I might set differently in a menu option? I've gone through about everything I can think of, including changing the position of the coax, the aforementioned choke on the keyboard cable, et. al., but can't figure out what's causing this. It acts like RF getting into the keyboard. I'll try a different keyboard while I wait for any suggestions, but other than that, I'm stuck. Being a member of 30MDG, I'd sort of like to be able to operate on 30! 73, Gwen NG3P -- -+-+-+-+- Jenny Everywhere's Infinite: Quark Time http://quarktime.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
