Re: [Elecraft] OCF antennas-Now way off Topic
Yes, I was a freshman in 1959 and while I never met Don Knuth, I heard plenty of stories about him. He was given free reign of the new computer center. 73, Don W3FPR On 3/11/2012 1:52 AM, Pete Michaelis - N8TR wrote: Don, When I started work at NASA's Lewis Research Center in the early 60's we often went to seminars at Case. Local legend had it that in one of Dr Green's classes he presented a research problem that he himself was working on and told the class that anyone solving it would be awarded a master's degree along with his BS. Donald E Knuth (author of the famous The Art of Computer Programming series of books) was in the class and solved the problem ( and got his BS MS in 1960). Did that happen while you were there? I know that this is way off topic but I have always been curious if that actually occurred. 73 Pete - N8TR At 08:40 PM 3/10/2012, Don Wilhelm wrote: __ 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
Re: [Elecraft] OCF antennas
Ian, I am with you on this. jmho that starting with whatever you can put up and for whatever reason that is all you can do at the time. If a new person doesn't get on the air fast he will soon lose interest. He is interested NOW, get him up and running and not next month or even next week if possible, NOW. I have also seen people with the location and resources who were excited and able to build an optimal station as their first station and do it all at once. Wrong thing to do. He built it, could talk anywhere and mostly anytime and within a year he was totally bored with it and never used it again and not long after sold it all. Coming up through all the pains of not having it all at once and learning what is better and why, trying to determine what will fit within the restrictions they are saddled with and taking the next step, making that better and then moving on is a great way to grow in knowledge and experience in building antennas. Another way to gain experience is to assist in the antenna parties in the area. In the beginning, waiting is wrong. Just DO it, operate, and ask questions, read, participate, join a club, BE where other hams are, LISTEN, learn, grow, modify, add, ask for help, try other antennas. as I said, jmho, 73, de Jim KG0KP - Original Message - From: Ian Kahn - Ham km4ik@gmail.com To: elecraft@mailman.qth.net Sent: Saturday, March 10, 2012 4:14 PM Subject: Re: [Elecraft] OCF antennas Dave, I wish to disagree with you on this point. Yes, this is a knowledge-based hobby. However, I learned enough to pass my exams and got a wire in the trees so I could get on the air. I've spent my time since then learning. You have the rest of your life to study and learn. We have no clue how long this sunspot cycle and good propagation conditions will last. Just my two cents' worth. I'll shut up now. --Ian Ian Kahn, KM4IK Roswell, GA km4ik@gmail.com K3 #281, P3 #688 On 3/10/2012 2:18 AM, David Gilbert wrote: Ham radio being a knowledge-based hobby, some people prefer to understand what they're doing. Apparently others don't seem to care. Dave AB7E On 3/9/2012 9:49 PM, Hisashi T Fujinaka wrote: So let me say one thing I know about antennas: PUT SOMETHING UP AND GET ON THE AIR. You can get perfect up, and you can get OK up. You an argue about what works better and what works worse. But when the bands are open, you might be able to work DX with a cantenna under your desk. (I've heard stories.) I used an untuned dipole with a LDG tuner to work my first (and only) DXCC back in the last sunspot cycle. So what I'm saying is put something up FIRST and then start the arguing, I mean, discussion. (But then again there are all sorts of aspects to the hobby and if you're here to argue you can if you want.) __ 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 __ 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 __ 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
Re: [Elecraft] OCF antennas
For those of you who enjoy discussing antennae there is a reflector to antennae here: anten...@mailman.qth.net. This reflector needs more traffic just like the antenna traffic on this net during the last week. Give it a try. 73, Tom Amateur Radio Operator N5GE ARRL Lifetime Member QCWA Lifetime Member On Sat, 10 Mar 2012 23:17:06 -0600, Jim Miller KG0KP jimmil...@stl-online.net wrote: Ian, I am with you on this. jmho that starting with whatever you can put up and for whatever reason that is all you can do at the time. If a new person doesn't get on the air fast he will soon lose interest. He is interested NOW, get him up and running and not next month or even next week if possible, NOW. [snip] __ 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
Re: [Elecraft] OCF antennas
To round off this part of the discussion I'll add that what Guy relates in terms of wet window line is to some extent also true when using insulated wire (rather than window line) with spacers approximately every 18 inches. I'm using #14 THNN in my feeders with Ladder Snap spacers and the wet settings on the tuner, while not drastically different, are different enough to warrant some retuning on some bands. 73, Gary W2CS -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft- boun...@mailman.qth.net] On Behalf Of Guy Olinger K2AV Sent: Sunday, March 11, 2012 12:49 AM To: j...@audiosystemsgroup.com Cc: elecraft@mailman.qth.net Subject: Re: [Elecraft] OCF antennas I have a 425 foot run of window line, specifically Wireman #554 down to my 160 antenna base. The detuning that is referred to is really a change in the dielectric: from PE to PE+water. That changes the loss (change = .5 dB at 1.830), but more particularly the velocity factor, which changes the electrical length and MOVES nodes and nulls. Here are the particulars from the line loss calculator in VK1OD's excellent collection of calculators at http://vk1od.net/calc/tl/tllc.php . Transmission Line Wireman 554 Code W554 Data source Wireman / N7WS Frequency 1.830 MHz Length 425.000 ft Results Zo 360.01-j1.74 Ω Velocity Factor, VF -2 0.928, 1.161 Length 306.76 °, 0.852 λ, 129.540 m Line Loss (matched) 0.251 dB Transmission Line Wireman 554 wet Code W554w Data source N7WS Frequency 1.830 MHz Length 425.000 ft Results Zo 344.94+j3.02 Ω Velocity Factor, VF -2 0.887, 1.271 Length 320.94 °, 0.892 λ, 129.540 m Line Loss (matched) 0.780 dB 73, Guy. On Sun, Mar 11, 2012 at 12:16 AM, Jim Brown j...@audiosystemsgroup.comwrote: On 3/10/2012 9:05 PM, Gary Ferdinand wrote: The OWL does not suffer from the dreaded detuning in the rain nearly to the extent of ladder line. Right. And while there is some change in the impedance, the primary effect is dielectric loss due to moisture on the solid portions of the window frame. 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 __ 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
Re: [Elecraft] OCF antennas-Now way off Topic
On Sun, Mar 11, 2012 at 12:52 AM, Pete Michaelis - N8TR pete.n...@gmail.com wrote: ...legend had it that in one of Dr Green's classes he presented a research problem that he himself was working on and told the class that anyone solving it would be awarded a master's degree... == for a similar story about one of the most important innovations in all of computer science, Google on Huffman coding history. Tony KT0NY -- http://www.isb.edu/faculty/facultydir.aspx?ddlFaculty=352 __ 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
Re: [Elecraft] OCF antennas
What I object to is the tone of your reply. I certainly said if you want to argue this to death, you can because that's an aspect of our hobby. You're saying I'm wrong, and I'm just trying to advocate for the guy who wants to get on the air FIRST, with something GOOD ENOUGH, and tinker LATER. Also, remember there are lot of variables that aren't taken into account and even if your antenna is better than mine, I might get out better because of my location. You can't know everything. So, geez, I've been trying to tone down my replies to you because you sound like you're mad all the time and that annoys me as well. I'm just advocating for more people to get on the air so I can work them. On Sun, 11 Mar 2012, David Gilbert wrote: That's not the point. There are those who enjoy ham radio for what they learn from it, and from optimizing their stations. There are others who simply enjoy operating and don't really care much what is behind it. Either are perfectly valid (this is a hobby, after all), but you're the one who seems to think that the latter has some level of esteem that the former does not. It doesn't. Some people like to build high performance cars but never drive them ... others couldn't care less what's under the hood and just want to race. Nobody is telling you to put your mic down and rigorously analyze your antennas ... don't tell the rest of us to quit trying to learn from each other on this forum so we can spend more time telling somebody what our weather is like. Dave AB7E On 3/10/2012 6:10 PM, Hisashi T Fujinaka wrote: I went to MIT. I can analyze the crap out of this if I feel like it. Or I can work DX and ragchew. Like I said, you use the hobby for what you want and I'm a proponent of the proverb that says, Perfect is the enemy of the good. On Sat, 10 Mar 2012, David Gilbert wrote: Ham radio being a knowledge-based hobby, some people prefer to understand what they're doing. Apparently others don't seem to care. Dave AB7E On 3/9/2012 9:49 PM, Hisashi T Fujinaka wrote: So let me say one thing I know about antennas: PUT SOMETHING UP AND GET ON THE AIR. You can get perfect up, and you can get OK up. You an argue about what works better and what works worse. But when the bands are open, you might be able to work DX with a cantenna under your desk. (I've heard stories.) I used an untuned dipole with a LDG tuner to work my first (and only) DXCC back in the last sunspot cycle. So what I'm saying is put something up FIRST and then start the arguing, I mean, discussion. (But then again there are all sorts of aspects to the hobby and if you're here to argue you can if you want.) __ 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 -- Hisashi T Fujinaka - ht...@twofifty.com BSEE(6/86) + BSChem(3/95) + BAEnglish(8/95) + MSCS(8/03) + $2.50 = latte __ 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
Re: [Elecraft] OCF antennas
Jim ... read your last paragraph. That's exactly what several of us were doing here when Hisashi wrote his first post on the topic. Dave AB7E On 3/10/2012 10:17 PM, Jim Miller KG0KP wrote: Ian, I am with you on this. jmho that starting with whatever you can put up and for whatever reason that is all you can do at the time. If a new person doesn't get on the air fast he will soon lose interest. He is interested NOW, get him up and running and not next month or even next week if possible, NOW. I have also seen people with the location and resources who were excited and able to build an optimal station as their first station and do it all at once. Wrong thing to do. He built it, could talk anywhere and mostly anytime and within a year he was totally bored with it and never used it again and not long after sold it all. Coming up through all the pains of not having it all at once and learning what is better and why, trying to determine what will fit within the restrictions they are saddled with and taking the next step, making that better and then moving on is a great way to grow in knowledge and experience in building antennas. Another way to gain experience is to assist in the antenna parties in the area. In the beginning, waiting is wrong. Just DO it, operate, and ask questions, read, participate, join a club, BE where other hams are, LISTEN, learn, grow, modify, add, ask for help, try other antennas. as I said, jmho, 73, de Jim KG0KP - Original Message - From: Ian Kahn - Hamkm4ik@gmail.com To:elecraft@mailman.qth.net Sent: Saturday, March 10, 2012 4:14 PM Subject: Re: [Elecraft] OCF antennas Dave, I wish to disagree with you on this point. Yes, this is a knowledge-based hobby. However, I learned enough to pass my exams and got a wire in the trees so I could get on the air. I've spent my time since then learning. You have the rest of your life to study and learn. We have no clue how long this sunspot cycle and good propagation conditions will last. Just my two cents' worth. I'll shut up now. --Ian Ian Kahn, KM4IK Roswell, GA km4ik@gmail.com K3 #281, P3 #688 On 3/10/2012 2:18 AM, David Gilbert wrote: Ham radio being a knowledge-based hobby, some people prefer to understand what they're doing. Apparently others don't seem to care. Dave AB7E On 3/9/2012 9:49 PM, Hisashi T Fujinaka wrote: So let me say one thing I know about antennas: PUT SOMETHING UP AND GET ON THE AIR. You can get perfect up, and you can get OK up. You an argue about what works better and what works worse. But when the bands are open, you might be able to work DX with a cantenna under your desk. (I've heard stories.) I used an untuned dipole with a LDG tuner to work my first (and only) DXCC back in the last sunspot cycle. So what I'm saying is put something up FIRST and then start the arguing, I mean, discussion. (But then again there are all sorts of aspects to the hobby and if you're here to argue you can if you want.) __ 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
Re: [Elecraft] OCF antennas [END of thread]
Guys, Must be a slow DX day.. Looks like we have beaten another topic into submission. When folks start getting grumpy, or the thread gets an over abundance of postings (both true here) its time to let it rest. Lot's of good info in this one, but let's remember that this -is- a hobby. We are all here to share our enjoyment of it with each other. It is -never- acceptable to make personal snipes at other postings made here. 73, Eric List Modulator www.elecraft.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
Re: [Elecraft] OCF antennas
2012/3/11 Gary Ferdinand alapa...@taconic.net To round off this part of the discussion I'll add that what Guy relates in terms of wet window line is to some extent also true when using insulated wire (rather than window line) with spacers approximately every 18 inches. I'm using #14 THNN in my feeders with Ladder Snap spacers and the wet settings on the tuner, while not drastically different, are different enough to warrant some retuning on some bands. 73, Gary W2CS Quite true. Enough so that using that using 14 or 12 THHN for a folded counterpoise experiences serious detuning in the rain, because it gets hanging drops all over it due to surface tension. For that and other reasons, we tell people to use bare wire only in an FCP. The FCP seems more sensitive than THHN and spreaders to the drops. 73, Guy. __ 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
Re: [Elecraft] OCF antennas [END of thread]
On Sun, Mar 11, 2012 at 1:41 PM, Eric Swartz WA6HHQ - Elecraft e...@elecraft.com wrote: Guys, Must be a slow DX day... That, actually is really true, with all the solar doings of the last week or so. Really blotto propagation on average. Kind of like the full moon. Folks start getting strange, DX withdrawal symptoms. :) 73, Guy __ 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
Re: [Elecraft] OCF antennas
On 3/9/2012 5:48 PM, Guy Olinger K2AV wrote: OCF antennas, under miscellaneous names, have been working fine, just fine, just about as long as radio. Working fine depends on your definition of the big picture, and your ability to diagnose problems. The problem with OCF antennas is COMMON MODE FEEDLINE CURRENT, which causes the feedline to receive noise, make the shack hot with RF, and radiate RF to the TV and stereoand computer in our living room (and our neighbor's living room). Fifty years ago, there was relatively little man made noise to be picked up on the feedline of our antennas, the equipment in our living room did not have Pin One Problems that turned all of the wiring into receiving and transmitting antennas, and the equipment in our neighbors' living room was not full of noise generators (other than their TV set's horizontal flyback system). Equally important, we had not LEARNED about common mode current on feedlines, and its contribution to these problems. We lived in blissful ignorance. We called CQ, we got responses, we had fun, but we also had TVI! And when the electronics world changed, introducing Pin One Problems, digital equipment, and switching power supplies to create noise, COMMON MODE CURRENT on feedlines started biting us in the behind, WHETHER WE KNEW IT OR NOT. As Guy and I have both noted, we can get away with unbalanced antennas if we choke them to death, but we're going to fry chokes if we run power unless we use MULTIPLE chokes. And choking them to death means multiple turns around ferrite cores (multiple cores and multiple chokes for high power). A FAR better solution, if we can do it, is resonant antennas for each band, well choked. If you're limited on space that can be done with fan dipoles or traps or loading coils. And there is NO MAGIC to parallel wire feedline -- there can be just as much common mode current on parallel wire line as on coax if the antenna itself is unbalanced. Balance is determined by the entire circuit -- the antenna, the feedline, and the transmitter (including the tuner), not ONLY the feedline. That's why I object to the words balanced feedline -- they are are pure fiction. 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
Re: [Elecraft] OCF antennas
I have very fond memories of my Carolina Windom 80 strung between two 50' Sycamore trees. I won my section of the 1999 Nov Sweepstakes and the 2000 ARRL Int.DX contest with that antenna an MFJ 949E tuner and 100W from my hand-me-down TS-520. Not bad for an antenna that can't work. -- R. Kevin Stover AC0H __ 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
Re: [Elecraft] OCF antennas
*Kevin, I worked the world in 1999 on an IC-706MKIIG, an SS750 Henry amplifier and a Gary Stookey built GS3 screwdriver antenna mounted on my Kenworth 18 wheeler in the US..but they don't work either eh? Oh well...I Can Only Monitor must mean something after all..TIC 73 Gary The nice man in the white coat coat is calling me...again * On 10 March 2012 22:14, Kevin kevin.sto...@mediacombb.net wrote: I have very fond memories of my Carolina Windom 80 strung between two 50' Sycamore trees. I won my section of the 1999 Nov Sweepstakes and the 2000 ARRL Int.DX contest with that antenna an MFJ 949E tuner and 100W from my hand-me-down TS-520. Not bad for an antenna that can't work. -- R. Kevin Stover AC0H __ 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 -- Gary VK4FD - Motorhome Mobile Elecraft Equipment K3 #679, KPA-500 #018 Living the dream!!! __ 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
Re: [Elecraft] OCF antennas
This thread has a count of 15. I thought I would squeeze one more in before the end of thread is called. Last year I performed some simple OCF Dipole investigations. My quest is to make a 15/20 trapped OCF dipole to place in an asymmetrical location in my attic. My rather incomplete notes can be found here: http://www.kn5l.net/ocfda/OCFDA.pdf My general finding for a OCF Dipole antenna are: EZNEC models, with accurate AGL parameters (including the Vee shape), are highly predictive within my ability to measure antenna parameters, Autek Model VA1 and KAT2 SWR meter. Best I can tell, a dual core 4:1 Balun does shunt coax shield currents. My observation is based on the EZNEC modeling versus actual measurements and noting that changing the feed-line length did not alter the measured antenna parameters. The off center ratio is highly dependent on antenna height for a relatively low antenna. So much so, that a single set of values will probably not be suitable for an application. If one wants to put up an optimal OCF Dipole, then you may want to use a modeling program or be prepared to perform a bunch of at location measurement and cuts to find the optimal values. A OCF Dipole does seem to work. I worked T32C using my K2/10 and the 15 meter OCF Dipole investigation antenna in my back yard. 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
Re: [Elecraft] OCF antennas
That's the most expensive latte I've ever seen. :-P 73, Mike NF4L On 3/9/2012 11:49 PM, Hisashi T Fujinaka wrote: So let me say one thing I know about antennas: PUT SOMETHING UP AND GET ON THE AIR. You can get perfect up, and you can get OK up. You an argue about what works better and what works worse. But when the bands are open, you might be able to work DX with a cantenna under your desk. (I've heard stories.) I used an untuned dipole with a LDG tuner to work my first (and only) DXCC back in the last sunspot cycle. So what I'm saying is put something up FIRST and then start the arguing, I mean, discussion. (But then again there are all sorts of aspects to the hobby and if you're here to argue you can if you want.) __ 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
Re: [Elecraft] OCF antennas
Probably the most elegant solution is to actually change the physical length of the element(s). Mike, KK5F, does that with jumpers on his portable dipole, and SteppIR does it by spooling up the un-wanted portion of the element. There was a design in QST that used air pressure to operate relays that accomplished the same thing. Maybe, this could also be done with relays powered by the signal. 73, Rick K7MW A FAR better solution, if we can do it, is resonant antennas for each band, well choked. If you're limited on space that can be done with fan dipoles or traps or loading coils. 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
Re: [Elecraft] OCF antennas
I'd put it this way: Some folks just want to get on the air and operate. Others take greater joy in knowing they can get the most out of what is available. There's room for a variety of operators. EVERY station is a collection of compromises. There is no perfect station or even a perfect portion. Antennas are part of that compromise, since available space, height and ground conditions, (no) tree etc. can vary greatly within a very short distance. The only 'perfect' antenna is the isotropic, which is hard to build. :o) An example of compromise is the commonly used portable rubber duck (AKA the semi-radiating dummy load). One can be more/less efficient, but it works and nothing is perfect. Keeping that in mind, most do the best they can with what they have. Both ends of the operator spectrum (soggy noodle antenna - every Pico watt out) make folks happy, so who's to complain? Some like QRP, some QRO, DX or not, ragchew or not, some are more technically minded and so on. While I tend to think it's wise to know WHY you're doing something and understanding what compromises you're accepting, I understand those that just want to get on the air and have fun. If you can afford heating the room (or hardware) with reasonable safety and you're having fun, have at it. Rick WA6NHC -Original Message- From: David Gilbert Ham radio being a knowledge-based hobby, some people prefer to understand what they're doing. Apparently others don't seem to care. Dave AB7E __ 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
Re: [Elecraft] OCF antennas
Well, I don't think you can blame OCF for TVI/RFI. You can blame radiating RF for TVI/RFI. Some of the best improvements in RF antennary were accompanied by increases in TVI/RFI, and that would include cleaning all that common mode current off the feedline so it only radiated off the driven element down toward the horizon like it should be. BTDT. Back in the day of 21 mc TV IF's, just sneezing on fifteen meters would cause TVI. If one only uses antennas that you don't have to think about, what fun would that be? Part of the draw of ham radio is making metal stuff work like an antenna, in spite of itself. 73, Guy PS, who doesn't know what mc is? On Sat, Mar 10, 2012 at 3:27 AM, Jim Brown j...@audiosystemsgroup.comwrote: On 3/9/2012 5:48 PM, Guy Olinger K2AV wrote: OCF antennas, under miscellaneous names, have been working fine, just fine, just about as long as radio. Working fine depends on your definition of the big picture, and your ability to diagnose problems. The problem with OCF antennas is COMMON MODE FEEDLINE CURRENT, which causes the feedline to receive noise, make the shack hot with RF, and radiate RF to the TV and stereoand computer in our living room (and our neighbor's living room). Fifty years ago, there was relatively little man made noise to be picked up on the feedline of our antennas, the equipment in our living room did not have Pin One Problems that turned all of the wiring into receiving and transmitting antennas, and the equipment in our neighbors' living room was not full of noise generators (other than their TV set's horizontal flyback system). Equally important, we had not LEARNED about common mode current on feedlines, and its contribution to these problems. We lived in blissful ignorance. We called CQ, we got responses, we had fun, but we also had TVI! And when the electronics world changed, introducing Pin One Problems, digital equipment, and switching power supplies to create noise, COMMON MODE CURRENT on feedlines started biting us in the behind, WHETHER WE KNEW IT OR NOT. As Guy and I have both noted, we can get away with unbalanced antennas if we choke them to death, but we're going to fry chokes if we run power unless we use MULTIPLE chokes. And choking them to death means multiple turns around ferrite cores (multiple cores and multiple chokes for high power). A FAR better solution, if we can do it, is resonant antennas for each band, well choked. If you're limited on space that can be done with fan dipoles or traps or loading coils. And there is NO MAGIC to parallel wire feedline -- there can be just as much common mode current on parallel wire line as on coax if the antenna itself is unbalanced. Balance is determined by the entire circuit -- the antenna, the feedline, and the transmitter (including the tuner), not ONLY the feedline. That's why I object to the words balanced feedline -- they are are pure fiction. 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 __ 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
Re: [Elecraft] OCF antennas
Dave, I wish to disagree with you on this point. Yes, this is a knowledge-based hobby. However, I learned enough to pass my exams and got a wire in the trees so I could get on the air. I've spent my time since then learning. You have the rest of your life to study and learn. We have no clue how long this sunspot cycle and good propagation conditions will last. Just my two cents' worth. I'll shut up now. --Ian Ian Kahn, KM4IK Roswell, GA km4ik@gmail.com K3 #281, P3 #688 On 3/10/2012 2:18 AM, David Gilbert wrote: Ham radio being a knowledge-based hobby, some people prefer to understand what they're doing. Apparently others don't seem to care. Dave AB7E On 3/9/2012 9:49 PM, Hisashi T Fujinaka wrote: So let me say one thing I know about antennas: PUT SOMETHING UP AND GET ON THE AIR. You can get perfect up, and you can get OK up. You an argue about what works better and what works worse. But when the bands are open, you might be able to work DX with a cantenna under your desk. (I've heard stories.) I used an untuned dipole with a LDG tuner to work my first (and only) DXCC back in the last sunspot cycle. So what I'm saying is put something up FIRST and then start the arguing, I mean, discussion. (But then again there are all sorts of aspects to the hobby and if you're here to argue you can if you want.) __ 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 __ 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
Re: [Elecraft] OCF antennas
I went to MIT. I can analyze the crap out of this if I feel like it. Or I can work DX and ragchew. Like I said, you use the hobby for what you want and I'm a proponent of the proverb that says, Perfect is the enemy of the good. On Sat, 10 Mar 2012, David Gilbert wrote: Ham radio being a knowledge-based hobby, some people prefer to understand what they're doing. Apparently others don't seem to care. Dave AB7E On 3/9/2012 9:49 PM, Hisashi T Fujinaka wrote: So let me say one thing I know about antennas: PUT SOMETHING UP AND GET ON THE AIR. You can get perfect up, and you can get OK up. You an argue about what works better and what works worse. But when the bands are open, you might be able to work DX with a cantenna under your desk. (I've heard stories.) I used an untuned dipole with a LDG tuner to work my first (and only) DXCC back in the last sunspot cycle. So what I'm saying is put something up FIRST and then start the arguing, I mean, discussion. (But then again there are all sorts of aspects to the hobby and if you're here to argue you can if you want.) __ 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 -- Hisashi T Fujinaka - ht...@twofifty.com BSEE(6/86) + BSChem(3/95) + BAEnglish(8/95) + MSCS(8/03) + $2.50 = latte __ 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
Re: [Elecraft] OCF antennas
On Sat, 10 Mar 2012, Jim Brown wrote: And there is NO MAGIC to parallel wire feedline I think the advantage (not magic) is that you get less loss in ladder line than you do through the dielectric of coax. -- Hisashi T Fujinaka - ht...@twofifty.com BSEE(6/86) + BSChem(3/95) + BAEnglish(8/95) + MSCS(8/03) + $2.50 = latte __ 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
Re: [Elecraft] OCF antennas (OT)
That reminds me of a couple of sayings: Good enough is perfect. There comes a time in any project when you need to shoot the engineers and start production. Bob N7XY On Mar 10, 2012, at 5:10 PM, Hisashi T Fujinaka wrote: I went to MIT. I can analyze the crap out of this if I feel like it. Or I can work DX and ragchew. Like I said, you use the hobby for what you want and I'm a proponent of the proverb that says, Perfect is the enemy of the good. On Sat, 10 Mar 2012, David Gilbert wrote: Ham radio being a knowledge-based hobby, some people prefer to understand what they're doing. Apparently others don't seem to care. Dave AB7E On 3/9/2012 9:49 PM, Hisashi T Fujinaka wrote: So let me say one thing I know about antennas: PUT SOMETHING UP AND GET ON THE AIR. You can get perfect up, and you can get OK up. You an argue about what works better and what works worse. But when the bands are open, you might be able to work DX with a cantenna under your desk. (I've heard stories.) I used an untuned dipole with a LDG tuner to work my first (and only) DXCC back in the last sunspot cycle. So what I'm saying is put something up FIRST and then start the arguing, I mean, discussion. (But then again there are all sorts of aspects to the hobby and if you're here to argue you can if you want.) __ 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 -- Hisashi T Fujinaka - ht...@twofifty.com BSEE(6/86) + BSChem(3/95) + BAEnglish(8/95) + MSCS(8/03) + $2.50 = latte __ 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 _ N7XY DX Cluster Node - telnet to n7xy.net, port 7300 __ 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
Re: [Elecraft] OCF antennas
And I went to CIT (Case Institute of Technology) - way back when - which was back in the '60s a rival for MIT in the forefront of engineering cutting edge technology. After suffering through Geunter's Green Book which was an attempt of an author promoting and refining his book advancing his math theories surrounding set theory, I think I got a decent math foundation. That was back in 1959, so conditions have changed and the focus has morphed to a software related analysis, I remain well entrenched in the hardware approach. While I can believe the software solution, I cannot devise a hardware parallel, and that is my problem. I have become a user of software solutions which include SDR. 73. Don W3FPR On 3/10/2012 8:10 PM, Hisashi T Fujinaka wrote: I went to MIT. I can analyze the crap out of this if I feel like it. Or I can work DX and ragchew. Like I said, you use the hobby for what you want and I'm a proponent of the proverb that says, Perfect is the enemy of the good. On Sat, 10 Mar 2012, David Gilbert wrote: Ham radio being a knowledge-based hobby, some people prefer to understand what they're doing. Apparently others don't seem to care. Dave AB7E On 3/9/2012 9:49 PM, Hisashi T Fujinaka wrote: So let me say one thing I know about antennas: PUT SOMETHING UP AND GET ON THE AIR. You can get perfect up, and you can get OK up. You an argue about what works better and what works worse. But when the bands are open, you might be able to work DX with a cantenna under your desk. (I've heard stories.) I used an untuned dipole with a LDG tuner to work my first (and only) DXCC back in the last sunspot cycle. So what I'm saying is put something up FIRST and then start the arguing, I mean, discussion. (But then again there are all sorts of aspects to the hobby and if you're here to argue you can if you want.) __ 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 __ 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
Re: [Elecraft] OCF antennas
Great humor, Hisashi Isn't it just so? So many years, so much experience, but the operations matter so much more. With my KX3 I am hauling out all my old self-made antennas, including a super flex multiband dipole in a 35 mm camera film can. Love to play. 73, Bill K9YEQ -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Hisashi T Fujinaka Sent: Saturday, March 10, 2012 7:10 PM To: David Gilbert Cc: elecraft@mailman.qth.net Subject: Re: [Elecraft] OCF antennas I went to MIT. I can analyze the crap out of this if I feel like it. Or I can work DX and ragchew. Like I said, you use the hobby for what you want and I'm a proponent of the proverb that says, Perfect is the enemy of the good. On Sat, 10 Mar 2012, David Gilbert wrote: Ham radio being a knowledge-based hobby, some people prefer to understand what they're doing. Apparently others don't seem to care. Dave AB7E On 3/9/2012 9:49 PM, Hisashi T Fujinaka wrote: So let me say one thing I know about antennas: PUT SOMETHING UP AND GET ON THE AIR. You can get perfect up, and you can get OK up. You an argue about what works better and what works worse. But when the bands are open, you might be able to work DX with a cantenna under your desk. (I've heard stories.) I used an untuned dipole with a LDG tuner to work my first (and only) DXCC back in the last sunspot cycle. So what I'm saying is put something up FIRST and then start the arguing, I mean, discussion. (But then again there are all sorts of aspects to the hobby and if you're here to argue you can if you want.) __ 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 -- Hisashi T Fujinaka - ht...@twofifty.com BSEE(6/86) + BSChem(3/95) + BAEnglish(8/95) + MSCS(8/03) + $2.50 = latte __ 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 __ 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
Re: [Elecraft] OCF antennas
Don, This explains much about your excellent approach to issues. I started in EE and changed to Economics in the 60's. I love electronics but the theories and dedication to such intricacies bored me to death. I love to play with radios, learn what I actually need and leave the rest to those who do best at the theory and studies. Building stuff is my love, including PC's with the software. 73, Bill K9YEQ -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Don Wilhelm Sent: Saturday, March 10, 2012 7:40 PM To: Hisashi T Fujinaka Cc: elecraft@mailman.qth.net Subject: Re: [Elecraft] OCF antennas And I went to CIT (Case Institute of Technology) - way back when - which was back in the '60s a rival for MIT in the forefront of engineering cutting edge technology. After suffering through Geunter's Green Book which was an attempt of an author promoting and refining his book advancing his math theories surrounding set theory, I think I got a decent math foundation. That was back in 1959, so conditions have changed and the focus has morphed to a software related analysis, I remain well entrenched in the hardware approach. While I can believe the software solution, I cannot devise a hardware parallel, and that is my problem. I have become a user of software solutions which include SDR. 73. Don W3FPR On 3/10/2012 8:10 PM, Hisashi T Fujinaka wrote: I went to MIT. I can analyze the crap out of this if I feel like it. Or I can work DX and ragchew. Like I said, you use the hobby for what you want and I'm a proponent of the proverb that says, Perfect is the enemy of the good. On Sat, 10 Mar 2012, David Gilbert wrote: Ham radio being a knowledge-based hobby, some people prefer to understand what they're doing. Apparently others don't seem to care. Dave AB7E On 3/9/2012 9:49 PM, Hisashi T Fujinaka wrote: So let me say one thing I know about antennas: PUT SOMETHING UP AND GET ON THE AIR. You can get perfect up, and you can get OK up. You an argue about what works better and what works worse. But when the bands are open, you might be able to work DX with a cantenna under your desk. (I've heard stories.) I used an untuned dipole with a LDG tuner to work my first (and only) DXCC back in the last sunspot cycle. So what I'm saying is put something up FIRST and then start the arguing, I mean, discussion. (But then again there are all sorts of aspects to the hobby and if you're here to argue you can if you want.) __ 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 __ 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 __ 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
Re: [Elecraft] OCF antennas
On 3/10/2012 5:14 PM, Hisashi T Fujinaka wrote: I think the advantage (not magic) is that you get less loss in ladder line than you do through the dielectric of coax. FALSE! For all practical purposes, there is NO dielectric loss in coax below about 500 MHz, where it just BEGINS to show up. Virtually all the loss in any dry transmission line at HF and VHF is due to simple Ohm's Law in the copper (including the increase in resistance due to skin effect). It's all I squared R loss. The advantage of open wire line is solely the result of their higher IMPEDANCE, which means that for a given power level, the CURRENT is much less. For the same reason, 75 ohm coax has a bit less loss than 50 ohm coax for the same conductor size. So-called WINDOW line loses this advantage when it gets wet, because then it DOES have dielectric loss. BTW -- when you're analyzing these things, you must consider the heat produced in a common mode choke when the antenna has a lot of imbalance. An off-center fed antenna has a LOT of imbalance. 73, Jim Brown 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
Re: [Elecraft] OCF antennas
On Sat, 10 Mar 2012, Jim Brown wrote: On 3/10/2012 5:14 PM, Hisashi T Fujinaka wrote: I think the advantage (not magic) is that you get less loss in ladder line than you do through the dielectric of coax. FALSE! For all practical purposes, there is NO dielectric loss in coax below about 500 MHz, where it just BEGINS to show up. Virtually all the loss in any dry transmission line at HF and VHF is due to simple Ohm's Law in the copper (including the increase in resistance due to skin effect). It's all I squared R loss. The advantage of open wire line is solely the result of their higher IMPEDANCE, which means that for a given power level, the CURRENT is much less. For the same reason, 75 ohm coax has a bit less loss than 50 ohm coax for the same conductor size. So-called WINDOW line loses this advantage when it gets wet, because then it DOES have dielectric loss. BTW -- when you're analyzing these things, you must consider the heat produced in a common mode choke when the antenna has a lot of imbalance. An off-center fed antenna has a LOT of imbalance. I think you're wrong here. The high SWRs generated along the feedline are extremely high voltages (with low currents) and there is significant loss in the dielectric of the coax. The reason that ladder line is better is because of the air in the dielectric. The best is the old school ladder line with the ceramic insulators. There is very little I squared R loss because there is very low current. That's why people see better performance with ladder line and think it's magic. -- Hisashi T Fujinaka - ht...@twofifty.com BSEE(6/86) + BSChem(3/95) + BAEnglish(8/95) + MSCS(8/03) + $2.50 = latte __ 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
Re: [Elecraft] OCF antennas
I think you're wrong here. The high SWRs generated along the feedline are extremely high voltages (with low currents) and there is significant loss in the dielectric of the coax. The reason that ladder line is better is because of the air in the dielectric. The best is the old school ladder line with the ceramic insulators. There is very little I squared R loss because there is very low current. That's why people see better performance with ladder line and think it's magic. I think in today's parlance many use the term ladder line to mean any flavor of non-coax, 2 conductor feedline. I distinguish between ladder line (insulated twin lead with holes) and open wire line (OWL) no insulating material other than the occasional spacer. Ceramic, plastic, etc. The OWL does not suffer from the dreaded detuning in the rain nearly to the extent of ladder line. 73, Gary W2CS __ 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
Re: [Elecraft] OCF antennas
On 3/10/2012 8:40 PM, Hisashi T Fujinaka wrote: I think you're wrong here. The math is VERY well known. There's are a couple of excellent technical papers about this in one of the ARRL Antenna Compendiums. Another place to see this is on the Times data sheets for their LMR cables. Look below the graph of loss vs frequency, where there is an equation for loss as a function of frequency. The first term is resistive loss and increases as the square root of frequency, the second is dielectric loss, and increases linearly with frequency. Put the equation in a spreadsheet and plot the curve. The square root term is skin effect. 73, Jim Brown 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
Re: [Elecraft] OCF antennas
On 3/10/2012 9:05 PM, Gary Ferdinand wrote: The OWL does not suffer from the dreaded detuning in the rain nearly to the extent of ladder line. Right. And while there is some change in the impedance, the primary effect is dielectric loss due to moisture on the solid portions of the window frame. 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
Re: [Elecraft] OCF antennas
On Sat, 10 Mar 2012, Jim Brown wrote: On 3/10/2012 8:40 PM, Hisashi T Fujinaka wrote: I think you're wrong here. The math is VERY well known. There's are a couple of excellent technical papers about this in one of the ARRL Antenna Compendiums. Another place to see this is on the Times data sheets for their LMR cables. Look below the graph of loss vs frequency, where there is an equation for loss as a function of frequency. The first term is resistive loss and increases as the square root of frequency, the second is dielectric loss, and increases linearly with frequency. Put the equation in a spreadsheet and plot the curve. The square root term is skin effect. Misapplied math is the worst of all. It's not the frequency you need to worry about, it's the high voltage breakdown. -- Hisashi T Fujinaka - ht...@twofifty.com BSEE(6/86) + BSChem(3/95) + BAEnglish(8/95) + MSCS(8/03) + $2.50 = latte __ 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
Re: [Elecraft] OCF antennas
I have a 425 foot run of window line, specifically Wireman #554 down to my 160 antenna base. The detuning that is referred to is really a change in the dielectric: from PE to PE+water. That changes the loss (change = .5 dB at 1.830), but more particularly the velocity factor, which changes the electrical length and MOVES nodes and nulls. Here are the particulars from the line loss calculator in VK1OD's excellent collection of calculators at http://vk1od.net/calc/tl/tllc.php . Transmission Line Wireman 554 Code W554 Data source Wireman / N7WS Frequency 1.830 MHz Length 425.000 ft Results Zo 360.01-j1.74 Ω Velocity Factor, VF -2 0.928, 1.161 Length 306.76 °, 0.852 λ, 129.540 m Line Loss (matched) 0.251 dB Transmission Line Wireman 554 wet Code W554w Data source N7WS Frequency 1.830 MHz Length 425.000 ft Results Zo 344.94+j3.02 Ω Velocity Factor, VF -2 0.887, 1.271 Length 320.94 °, 0.892 λ, 129.540 m Line Loss (matched) 0.780 dB 73, Guy. On Sun, Mar 11, 2012 at 12:16 AM, Jim Brown j...@audiosystemsgroup.comwrote: On 3/10/2012 9:05 PM, Gary Ferdinand wrote: The OWL does not suffer from the dreaded detuning in the rain nearly to the extent of ladder line. Right. And while there is some change in the impedance, the primary effect is dielectric loss due to moisture on the solid portions of the window frame. 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
Re: [Elecraft] OCF antennas-Now way off Topic
Don, When I started work at NASA's Lewis Research Center in the early 60's we often went to seminars at Case. Local legend had it that in one of Dr Green's classes he presented a research problem that he himself was working on and told the class that anyone solving it would be awarded a master's degree along with his BS. Donald E Knuth (author of the famous The Art of Computer Programming series of books) was in the class and solved the problem ( and got his BS MS in 1960). Did that happen while you were there? I know that this is way off topic but I have always been curious if that actually occurred. 73 Pete - N8TR At 08:40 PM 3/10/2012, Don Wilhelm wrote: And I went to CIT (Case Institute of Technology) - way back when - which was back in the '60s a rival for MIT in the forefront of engineering cutting edge technology. After suffering through Geunter's Green Book which was an attempt of an author promoting and refining his book advancing his math theories surrounding set theory, I think I got a decent math foundation. __ 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
Re: [Elecraft] OCF antennas
That's not the point. There are those who enjoy ham radio for what they learn from it, and from optimizing their stations. There are others who simply enjoy operating and don't really care much what is behind it. Either are perfectly valid (this is a hobby, after all), but you're the one who seems to think that the latter has some level of esteem that the former does not. It doesn't. Some people like to build high performance cars but never drive them ... others couldn't care less what's under the hood and just want to race. Nobody is telling you to put your mic down and rigorously analyze your antennas ... don't tell the rest of us to quit trying to learn from each other on this forum so we can spend more time telling somebody what our weather is like. Dave AB7E On 3/10/2012 6:10 PM, Hisashi T Fujinaka wrote: I went to MIT. I can analyze the crap out of this if I feel like it. Or I can work DX and ragchew. Like I said, you use the hobby for what you want and I'm a proponent of the proverb that says, Perfect is the enemy of the good. On Sat, 10 Mar 2012, David Gilbert wrote: Ham radio being a knowledge-based hobby, some people prefer to understand what they're doing. Apparently others don't seem to care. Dave AB7E On 3/9/2012 9:49 PM, Hisashi T Fujinaka wrote: So let me say one thing I know about antennas: PUT SOMETHING UP AND GET ON THE AIR. You can get perfect up, and you can get OK up. You an argue about what works better and what works worse. But when the bands are open, you might be able to work DX with a cantenna under your desk. (I've heard stories.) I used an untuned dipole with a LDG tuner to work my first (and only) DXCC back in the last sunspot cycle. So what I'm saying is put something up FIRST and then start the arguing, I mean, discussion. (But then again there are all sorts of aspects to the hobby and if you're here to argue you can if you want.) __ 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
Re: [Elecraft] OCF antennas
On Fri, Mar 9, 2012 at 3:50 PM, Bill b...@w2blc.net wrote: I have found the easiest single antenna to utilize is the OCF... The OCF has advantages and can work very well. I have had good success with several versions, and in fact published an article in QST about one such setup (March 2006). It's important to note that any OCF antenna will have common-mode current flowing on the feedline, which will produce RF in the shack. With modest power this is usually not a problem, but as power goes up, the effects get worse. If the antenna is coax-fed, the common-mode RF can be choked off with a 1:1 balun or an isolator. If it's fed with balanced line, it should go to a balun and thence to a coax link to the transmitter, and that coax should have provisions for choking the RF. The cold side of the isolator should be grounded to a good RF ground (i.e. not just a ground rod or water pipe -- ideally, a counterpoise or radial system, or other really good RF sink). The feedline will radiate, and this should be included in your EZNEC or other model when determining the radiation pattern. Tony KT0NY -- http://www.isb.edu/faculty/facultydir.aspx?ddlFaculty=352 __ 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
Re: [Elecraft] OCF antennas
When I got on the air at this QTH in 2006 I installed a Carolina Windom from Radio Works. It is about 40 feet high and fed with a short piece of RG8X. I thought it a great antenna and worked some contests and a lot of DX. Later, I installed a 30 foot vertical with one radial and found it much superior on 40 and 15. Then I installed a 65 ft tower with a 3 element SteppIR 30/40 and worked DXCC in 31 days. Then I installed a 40 and 80 inverted Vee fed with a common coax. Then I installed an Inverted L with an 80 meter trap for 80 and 160. The Carolina Windom is still up, but it is not the preferred antenna for any band at any distance. I find that the OCF is the best antenna only if it is your only antenna, but I have not compared it to a Buddy Pole. Willis 'Cookie' Cooke K5EWJ Trustee N5BPS, USS Cavalla, USS Stewart From: Bill b...@w2blc.net To: elecraft@mailman.qth.net Sent: Friday, March 9, 2012 3:50 PM Subject: [Elecraft] OCF antennas I have found the easiest single antenna to utilize is the OCF - it is coax fed, making easy routing of the feedline. The K3's ATU handles it fine (as does my TS-480 SAT). Dimensions for the version I use: 88' on one leg and 44 ' on the other leg. For a center insulator/balun I use the http://www.balundesigns.com/servlet/the-75/OCF-balun-4-cln-1/Detail I use #12 stranded insulated wire (not house wire) available from any of several ham distributors. Works FB for what I do with it, which is mostly rag chew on 40 and 75 SSB. However, I have used on the higher bands with good success also. The pattern does get somewhat directional as you move up from the primary design frequency. If you have room for a couple of them at right angles - that might be of an advantage. Bill W2BLC __ 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 __ 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
Re: [Elecraft] OCF antennas
I didn't mention the RF on the feedline, as I am in the habit of choking all feedlines coming into the house. Easy: 10 turns of coax 6 or 8 inches diameter and cable tied just outside the wall - prior to the grounding panels. Use one of the flex type cables and it will be easy. Bill W2BLC __ 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
Re: [Elecraft] OCF antennas
On 3/9/2012 1:50 PM, Bill wrote: I have found the easiest single antenna to utilize is the OCF Off center fed antennas are a recipe for noise pickup on the feedline. While a good common mode choke can help, off-center feed can also burn up a common mode choke if you're running much power. Bottom line -- off-center-fed antennas are a bad idea. 73, Jim Brown 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
Re: [Elecraft] OCF antennas
On 3/9/2012 2:14 PM, WILLIS COOKE wrote: When I got on the air at this QTH in 2006 I installed a Carolina Windom from Radio Works. It is about 40 feet high and fed with a short piece of RG8X. I thought it a great antenna and worked some contests and a lot of DX. Later, I installed a 30 foot vertical with one radial and found it much superior on 40 and 15. Then I installed a 65 ft tower with a 3 element SteppIR 30/40 and worked DXCC in 31 days. Then I installed a 40 and 80 inverted Vee fed with a common coax. Then I installed an Inverted L with an 80 meter trap for 80 and 160. The Carolina Windom is still up, but it is not the preferred antenna for any band at any distance. I find that the OCF is the best antenna only if it is your only antenna, but I have not compared it to a Buddy Pole. If you keep installing antennas and don't take any down, will you ever have enough? The Buddipole, using the horizontal loaded dipole recipe in the documentation, is an OCF configuration to improve the match, and the line has current on it. Not a problem for my K2 or KX1 at 5 or 3W. Maybe not true for 100+ watts. I've been using a center-loaded recipe with radials made from the longer BP extendable elements. Seems to work better than the horizontal configs. 73, Fred K6DGW - Northern California Contest Club - CU in the 2012 Cal QSO Party 6-7 Oct 2012 - www.cqp.org __ 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
Re: [Elecraft] OCF antennas
Well said Jim, There is no way to obtain equal and opposite currents on the feedline with an offset fed antenna - they are a sure recipe for RF-in-the-shack. As much acclaim as the Carolina Windom gets, that fact is still true, one just cannot run high power with such an antenna - at low power the RF levels may be tolerable, but at high power, they can wreak havoc in the shack with RF all over everything. 73, Don W3FPR On 3/9/2012 5:58 PM, Jim Brown wrote: On 3/9/2012 1:50 PM, Bill wrote: I have found the easiest single antenna to utilize is the OCF Off center fed antennas are a recipe for noise pickup on the feedline. While a good common mode choke can help, off-center feed can also burn up a common mode choke if you're running much power. Bottom line -- off-center-fed antennas are a bad idea. 73, Jim Brown K9YC This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ 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
Re: [Elecraft] OCF antennas
OCF antennas, under miscellaneous names, have been working fine, just fine, just about as long as radio. We just have 50 ohm coax and SWR meters on the brain, and have a terrible time seeing outside the rather narrow 50 ohm coax/low SWR box. And we're boxing ourselves in further with single-Z transistor amps that fall off the table and go blurg off 50 ohm Z. (Whatever happened to I-don't-give-a-d*mn-about-SWR tetrode amps, like 807's, 6146's and 4CX1000A? I worked DXCC and had a BPL medallion before I ever had an SWR meter. Just can't understand how I managed. :)Oops, forgot, Alpha's 8410 monster uses a pair of those 4CX1000A's, and it really doesn't give a d*mn about swr, either.) One famous (back in the day) OCF oldie is the ORIGINAL Windom, the single wire feed version Windom, decidedly an OCF. It's only a single band antenna, but you feed the single up wire with a 9:1 auto transformer at the ground against what can be minimal to almost non-existent radials since the Z is 400-450 ohms at the bottom of the feed wire, and it takes an absolute totally ugly resistive stinking ground connection to mess it up. Very useful on field days. It's supreme mechanical advantage is that the single wire feedline can be a single stranded #18 wire, even for QRO, far and away lighter than any other feedline. This means you can get what amounts to weird-fed 80 and 40 dipoles WAY up there, that are only supported at the ends, without all the weight issues. How does it work? It USES the common mode feedline induction from the long side of the OCF dipole, to work against the opposite phase coming from the feed (it's the same piece of wire). If you monkey with it a bit in a model, you can pick a connection point for the single wire feed where the current is flat all the way up, no standing waves, which means it is radiating very little from the feed. Or you can move it around a bit and PICK the amount of vertical radiation you would like to mix in. But that changes the feed Z. Disadvantage?, you can't buy the 9:1 autotransformer off the shelf any old where and you may have to roll your own. OCF antennas in general CAN be tamed at QRO, but one needs to know to do it. Just running a feedline to it and putting power on it WILL get you RF in the shack as others have opined. Using an isolation device at the antenna end only gets PART of the problem. The other part is that the now isolated feed line is STILL off center approaching the OCF antenna. This in and of itself will cause the isolated antenna to induce current on the feedline shield, because the long part of the antenna at right angles to the feed line induces more current to the feedline than the opposite phase current from the short part. This is not a problem in a dipole where ordinary (and fairly weak) devices pull off any needed isolation. Weak isolating devices will not cut it for OCF. A SECOND isolation device down the coax a bit, that breaks up the coax shield into a non-resonant length next to the antenna, will prevent the RF in the shack AND it will clean up the pattern to what the models say it should be, usually a performance plus. Care needs to be taken to the suitability of the isolation devices for the two uses. Some antennas use the second device as the ONLY device and deliberately use a length of the shield as a common mode radiator. No advertising needed. If you suspect that cleaning up all this tends to work against multiband use and makes doing OCF well a chess game, you suspect correctly. Portable use at 100 watts without all the isolators will work just fine. OCF's have been a mainstay of field day use as long as that has been going on. My K2/10, with the built-in ATU and the itty bitty balun love those antennas and never had the first problem. 73, Guy. On Fri, Mar 9, 2012 at 7:09 PM, Don Wilhelm w3...@embarqmail.com wrote: Well said Jim, There is no way to obtain equal and opposite currents on the feedline with an offset fed antenna - they are a sure recipe for RF-in-the-shack. As much acclaim as the Carolina Windom gets, that fact is still true, one just cannot run high power with such an antenna - at low power the RF levels may be tolerable, but at high power, they can wreak havoc in the shack with RF all over everything. 73, Don W3FPR On 3/9/2012 5:58 PM, Jim Brown wrote: On 3/9/2012 1:50 PM, Bill wrote: I have found the easiest single antenna to utilize is the OCF Off center fed antennas are a recipe for noise pickup on the feedline. While a good common mode choke can help, off-center feed can also burn up a common mode choke if you're running much power. Bottom line -- off-center-fed antennas are a bad idea. 73, Jim Brown K9YC This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home:
Re: [Elecraft] OCF antennas
On Fri, Mar 9, 2012 at 7:48 PM, Guy Olinger K2AV olin...@bellsouth.net wrote: OCF antennas, under miscellaneous names, have been working fine... = Of course. Please note that the Elecraft product line was originally designed to be used with an end-fed wire (the ultimate in off-center feed), or with a long wire fed against a short counterpoise. It's pretty far-fetched to say that OCF antenna are no good -- they radiate and they receive. I worked 260 countries in a year with an OCF antenna that I used on all bands 80-10. An OCF antenna may require more knowledge from its user than a coax-fed dipole, but that doesn't mean it won't work. If you set it up properly it will work. If you don't, RF will come into your shack and bite you, and you'll be unhappy. But there's a lot of ham gear that doesn't give good results when set up wrong. Tony KT0NY -- http://www.isb.edu/faculty/facultydir.aspx?ddlFaculty=352 __ 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
Re: [Elecraft] OCF antennas
So let me say one thing I know about antennas: PUT SOMETHING UP AND GET ON THE AIR. You can get perfect up, and you can get OK up. You an argue about what works better and what works worse. But when the bands are open, you might be able to work DX with a cantenna under your desk. (I've heard stories.) I used an untuned dipole with a LDG tuner to work my first (and only) DXCC back in the last sunspot cycle. So what I'm saying is put something up FIRST and then start the arguing, I mean, discussion. (But then again there are all sorts of aspects to the hobby and if you're here to argue you can if you want.) -- Hisashi T Fujinaka - ht...@twofifty.com BSEE(6/86) + BSChem(3/95) + BAEnglish(8/95) + MSCS(8/03) + $2.50 = latte __ 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
Re: [Elecraft] OCF antennas
Right on! Rick K6LE On 3/9/2012, at 8:49 , Hisashi T Fujinaka ht...@twofifty.com wrote: So let me say one thing I know about antennas: PUT SOMETHING UP AND GET ON THE AIR. __ 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
Re: [Elecraft] OCF antennas
Ham radio being a knowledge-based hobby, some people prefer to understand what they're doing. Apparently others don't seem to care. Dave AB7E On 3/9/2012 9:49 PM, Hisashi T Fujinaka wrote: So let me say one thing I know about antennas: PUT SOMETHING UP AND GET ON THE AIR. You can get perfect up, and you can get OK up. You an argue about what works better and what works worse. But when the bands are open, you might be able to work DX with a cantenna under your desk. (I've heard stories.) I used an untuned dipole with a LDG tuner to work my first (and only) DXCC back in the last sunspot cycle. So what I'm saying is put something up FIRST and then start the arguing, I mean, discussion. (But then again there are all sorts of aspects to the hobby and if you're here to argue you can if you want.) __ 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
Re: [Elecraft] OCF antennas
K2AV wrote: We just have 50 ohm coax and SWR meters on the brain, and have a terrible time seeing outside the rather narrow 50 ohm coax/low SWR box. And we're boxing ourselves in further with single-Z transistor amps that fall off the table and go blurg off 50 ohm Z. (Whatever happened to I-don't-give-a-d*mn-about-SWR tetrode amps, like 807's, 6146's and 4CX1000A? I worked DXCC and had a BPL medallion before I ever had an SWR meter. Just can't understand how I managed. :)Oops, forgot, Alpha's 8410 monster uses a pair of those 4CX1000A's, and it really doesn't give a d*mn about swr, either.) --- Yes, but those nice ole tube amps almost universally used pi-net outputs which are tuners in-fact. Ferrites make wide-band transformation possible so solid-state no-tune amps are possible. Transistor impedances are so low it makes it critical to load them properly. But we seem to come full circle back to using tuners. I bought a small mobile MFJ-945E tuner for my station due to being on a budget. When I got the K3/10 it worked very nice with my array of 18 antennas. Later a friend was selling an old Drake QRO tuner so I bought it (MN2000) and it now tunes the output of my new 300w HF amp. Too bad it does not have 160m. It has two coax antenna outputs (direct or tuned) so I have one connected to a dummy load and the other to my 5-pos antenna switch (manual). I will eventually run the output of the K3/10 thru the MFJ to a 4-pos coax switch to chose either 6m, 6m-eme, or HF (with a spare position unused). The HF pos. goes to the 300w amp which has a bypass relay, so I can run QRP or with some power. The Drake tuner works really nice and has a power meter to monitor the HF amp so I do not have to commit my Bird43 to that. I sure like the big knobs for tuning and smooth operation of them. 73, Ed - KL7UW, WD2XSH/45 == BP40IQ 500 KHz - 10-GHz www.kl7uw.com EME: 50-1.1kw?, 144-1.4kw, 432-QRT, 1296-?, 3400-? DUBUS Magazine USA Rep dubus...@gmail.com Kits made by KL7UW http://www.kl7uw.com/kits.htm == __ 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
