K2 s/n 4276 Output Power Instability
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K2 s/n 4276
Firmware Revision(s): 2.04P 1.09 After having a previous issue with the VCO alignment (p. 61), construction went forward without a hitch. At this point, I figured that any gremlins had been banished. Not so. Another pesky gremlin has reared it's ugly head. During transmitter alignment, the initial 40 meter alignment went down in accordance with the manual's expectations. Receiver pre-alignment was straight forward. Alignment of 20 and 30 meter transmit went fine, then from that point on, it all went downhill and the current issue began. Regardless of which band or power setting, on entering TUNE, the power out readings rapidly vary across the entire scale. These rapidly changing readings are also reflected on my Diamond SK-600 power/SWR meter as well as the readigs on the current meter of the power supply. After a brief bit of time, the power out will sometimes stop fluctuating and settle down to the requested power setting. Might this be a problem with U-6, on the control board? I would appreciate any insight of the possible cause of this issue and suggestions of any possible sollutions. 73's William Smith KC4WVL _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: K2 s/n 4276 Output Power Instability
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William,
You said 40, 30 and 20 worked once, but not now - that says any problem is in an area shared by all bands. The first thing to do would be to check the coax cables, any adapters and the dummy load for a bad connection. I prefer to reduce any extra things in the setup because they too can be a source of trouble (and they are often overlooked). Connect the K2 using a short piece of known good coax to a known good dummy load and try again. If you continue to have problems, go back to 40 meters (which once worked) and use the Transmit Signal Tracing steps in the back of the manual to determine the failing stage. If you have not already constructed the RF Probe from the supplied parts, now is a good time to do that. We can help further if we know more about the failing stage or stages - right now, all we can say is that something is wrong somewhere - either inside or outside the K2. I would not suspect U6 at this point - if you have a problem with the power control only, take a critical look at the Keying waveshape components mounted on the back of the Control Board (yes, they are part of the power control loop). 73, Don W3FPR kc4wvl wrote: > K2 s/n 4276 > Firmware Revision(s): 2.04P 1.09 > > After having a previous issue with the VCO alignment (p. 61), construction went forward without a hitch. At this point, I figured that any gremlins had been banished. Not so. > > Another pesky gremlin has reared it's ugly head. During transmitter alignment, the initial 40 meter alignment went down in accordance with the manual's expectations. Receiver pre-alignment was straight forward. Alignment of 20 and 30 meter transmit went fine, then from that point on, it all went downhill and the current issue began. Regardless of which band or power setting, on entering TUNE, the power out readings rapidly vary across the entire scale. These rapidly changing readings are also reflected on my Diamond SK-600 power/SWR meter as well as the readigs on the current meter of the power supply. After a brief bit of time, the power out will sometimes stop fluctuating and settle down to the requested power setting. > > Might this be a problem with U-6, on the control board? > > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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I admit I enjoyed using a KAT100 at FD, but I wonder
how much value it would be at my station. For feeding my wire antenna with balanced line, I suspect I need an external balun, that has to go someplace, and better to be attached to one of the tuner inputs. Currently I use a manual MFJ tuner (with its internal 4:1 balun) to operate my wire antenna on 30, 40, 80 and 160m. I can imagine the autotuner being useful here, but I can't envision the balun to use and how to attach it to the KAT100. My other antennas are 2 multiband verticals (80/40 and 20/17/15/12/10), and these are nicely matched where I operate - so not much utility for the KAT100 here. So will a KAT100 make my QSY more seamless, and what balun to use and how to integrate it ? 73, curt ____________________________________________________________________________________ Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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For Field Day this year I had my K2 hooked up to a 130' dipole fed by ladder
line. We ran that to a 4:1 balun and a few feet of coax to the KAT100. It tuned it up nicely on all bands. We had no trouble working anyone we called. Craig NZ0R -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Curt Milton Sent: Thursday, November 15, 2007 11:50 AM To: [hidden email] Subject: [Elecraft] KAT100 with Ladder Line I admit I enjoyed using a KAT100 at FD, but I wonder how much value it would be at my station. For feeding my wire antenna with balanced line, I suspect I need an external balun, that has to go someplace, and better to be attached to one of the tuner inputs. Currently I use a manual MFJ tuner (with its internal 4:1 balun) to operate my wire antenna on 30, 40, 80 and 160m. I can imagine the autotuner being useful here, but I can't envision the balun to use and how to attach it to the KAT100. My other antennas are 2 multiband verticals (80/40 and 20/17/15/12/10), and these are nicely matched where I operate - so not much utility for the KAT100 here. So will a KAT100 make my QSY more seamless, and what balun to use and how to integrate it ? 73, curt ____________________________________________________________________________ ________ Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Curt Milton
Curt,
There seems to be a misconception among hams that when using 450 ladder line, a 4:1 balun is the best thing to use. While that may be true in some cases, in many other cases, a 1:1 balun will serve better. It all depends on the feedpoint impedance of the feedline at the shack end, and that has little relationship with the fact that 450 ohm line is being used - i.e. the feedpoint impedance is *not* the characteristic impedance of the transmission line in most cases. The feedpoint impedance looking into the shack end of a multiband antenna can vary from extremely low to extremely high - it all depends on the length of the antenna and the length of the feedline. That being said, I would suggest that you use an Elecraft BL2 right at the output of the KAT100. Try it at the 1:1 setting first, and then try the 4:1 setting to see which produces the better results for each band. It would be informative to measure the impedance into the unbalanced end of the balun with an antenna analyzer on each band - use the setting that does not produce an extremely low of extremely high SWR on the analyzer. Often adding or subtracting a length of feedline will bring the feedpoint impedance into a better range for matching. 73, Don W3FPR Curt Milton wrote: > I admit I enjoyed using a KAT100 at FD, but I wonder > how much value it would be at my station. > > For feeding my wire antenna with balanced line, I > suspect I need an external balun, that has to go > someplace, and better to be attached to one of the > tuner inputs. Currently I use a manual MFJ tuner > (with its internal 4:1 balun) to operate my wire > antenna on 30, 40, 80 and 160m. I can imagine the > autotuner being useful here, but I can't envision the > balun to use and how to attach it to the KAT100. > > My other antennas are 2 multiband verticals (80/40 and > 20/17/15/12/10), and these are nicely matched where I > operate - so not much utility for the KAT100 here. > > So will a KAT100 make my QSY more seamless, and what > balun to use and how to integrate it ? > > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Using any balun with an unbalanced tuner to feed balanced line can be
bad news (your mileage may vary, standard disclaimers apply). Under highly reactive loads, a balun used like this can become quite lossy. There's a couple articles in publications and on the Internet on this, but Cebik's article is one that comes to mind ( http://www.cebik.com/link/l-bal.html ). It's better to run a real balanced tuner like a Johnson Matchbox, the MFJ Balanced Line tuner, or others, if you can. Don Wilhelm wrote: > Curt, > > There seems to be a misconception among hams that when using 450 > ladder line, a 4:1 balun is the best thing to use. While that may be > true in some cases, in many other cases, a 1:1 balun will serve > better. It all depends on the feedpoint impedance of the feedline at > the shack end, and that has little relationship with the fact that 450 > ohm line is being used - i.e. the feedpoint impedance is *not* the > characteristic impedance of the transmission line in most cases. The > feedpoint impedance looking into the shack end of a multiband antenna > can vary from extremely low to extremely high - it all depends on the > length of the antenna and the length of the feedline. Blog: http://thek3ngreport.blogspot.com/ _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: KAT100 with Ladder Line
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On Thursday, November 15, 2007 at 7:00 PM, Goody K3NG wrote:
> Using any balun with an unbalanced tuner to feed balanced line can be bad > news (your mileage may vary, standard disclaimers apply). Under highly > reactive loads, a balun used like this can become quite lossy. There's a > couple articles in publications and on the Internet on this, but Cebik's > article is one that comes to mind ( > http://www.cebik.com/link/l-bal.html ). It's better to run a real > balanced tuner like a Johnson Matchbox, the MFJ Balanced Line tuner, or > others, if you can. --------------------------------------------------------- Well put Sir! As a comment to the List, the usual type of cored current balun presented with a reactive load might appear not to be introducing loss because QSOs can be made, but as the members of our QRP fraternity well know contacts both 'local' and DX can be made using very low power given the right propagation conditions. Proof of this loss can be had by increasing Tx power up to the power rating of the balun at which point the balun could well explode if it has not already at a lower power, it will certainly becomes hot to touch. As K3NG says your mileage might vary because the antenna's feedpoint impedance as transformed by your feeder and seen by the balun might by happy fluke be non-reactive, feeder length and feeder impedance are factors, leaving only the R to deal with. If R turns out to be 200 ohms, then a 1:4 balun would work well with a Tx which wants to see a load of 50 +j0. FWIW I agree with K3NG that the classic balanced tuner such as used in the Matchbox is the best system to use when feeding a balanced line, good efficiency and versatile. 73, Geoff GM4ESD _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Goody K3NG
You are quite correct. My favorite tuner of all is a link coupled
balanced tuner, and it is L B Cebik's favorite too - low loss and can be configured to match just about anything - series tuning for low impedances or parallel for higher impedances. I have built many over the years. No balun required anywhere. If I were able to bring ladderline into the shack, I would have one of my old balanced tuners with the plug-in coils to match the transmitter to the ladderline - but I can't do that (don't ask!), so I use resonant antennas fed with coax and clean up any required additional tuning with a KAT100. But, one must admit that the KAT100 does offer a lot of convenience to the operator, even though it has some drawbacks - it is not balanced, and for those who are fortunate enough to bring ladderline into the shack, it can be used with a balun. It is a workable solution as long as some cautions are observed to minimize the loss. One cannot defeat the laws of physics, but for those who must use an unbalanced tuner and a ladderline fed multiband antenna, the KAT100 followed by a balun may be an acceptable solution. Adjust the feedline length so as to provide a decent feedpoint impedance at the balun without a lot of reactance, and use a current type balun (a voltage balun just will not work well in this application), and one can get on the air - it certainly is better than no antenna at all. 73, Don W3FPR Goody K3NG wrote: > Using any balun with an unbalanced tuner to feed balanced line can be > bad news (your mileage may vary, standard disclaimers apply). Under > highly reactive loads, a balun used like this can become quite lossy. > There's a couple articles in publications and on the Internet on this, > but Cebik's article is one that comes to mind ( > http://www.cebik.com/link/l-bal.html ). It's better to run a real > balanced tuner like a Johnson Matchbox, the MFJ Balanced Line tuner, > or others, if you can. > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Geoffrey Mackenzie-Kennedy
I've been using Cecil Moore's (W6RCA) "No-Tuner" with 450 ohm ladder
line for about 7 years along with a K2 / KAT-2 and it has been a pleasure to use and pretty effective. It's basically a box of 5 4pdt relays out in the yard that switches in/out combinations of 16, 8, 4, 2 and 1 foot lengths of 450 ohm ladder line to the main 450 ohm feedline to get a close match in the shack, and the KAT2 does the rest. The input to the relay box is fed with RG8X with a bead balun on the coax right at the box input. The idea is to switch just enough extra line in to get a current antinode at the antenna feedpoint for the frequency of operation. For a 80 meter half wave antenna (with 10 meter fan element tacked on), the main 450 ohm feedline is about 85-90 feet long. I've worked/confirmed ~140 countries using this antenna with 12 watts or less (mostly 5 watts). And I'm not much of a dx fanatic. 73, Lenny W2BVH Geoffrey Mackenzie-Kennedy wrote: > On Thursday, November 15, 2007 at 7:00 PM, Goody K3NG wrote: > >> Using any balun with an unbalanced tuner to feed balanced line can be >> bad news (your mileage may vary, standard disclaimers apply). Under >> highly reactive loads, a balun used like this can become quite >> lossy. There's a couple articles in publications and on the Internet >> on this, but Cebik's article is one that comes to mind ( >> http://www.cebik.com/link/l-bal.html ). It's better to run a real >> balanced tuner like a Johnson Matchbox, the MFJ Balanced Line tuner, >> or others, if you can. > > --------------------------------------------------------- > > Well put Sir! > > As a comment to the List, the usual type of cored current balun > presented with a reactive load might appear not to be introducing loss > because QSOs can be made, but as the members of our QRP fraternity > well know contacts both 'local' and DX can be made using very low > power given the right propagation conditions. Proof of this loss can > be had by increasing Tx power up to the power rating of the balun at > which point the balun could well explode if it has not already at a > lower power, it will certainly becomes hot to touch. As K3NG says your > mileage might vary because the antenna's feedpoint impedance as > transformed by your feeder and seen by the balun might by happy fluke > be non-reactive, feeder length and feeder impedance are factors, > leaving only the R to deal with. If R turns out to be 200 ohms, then a > 1:4 balun would work well with a Tx which wants to see a load of 50 +j0. > > FWIW I agree with K3NG that the classic balanced tuner such as used in > the Matchbox is the best system to use when feeding a balanced line, > good efficiency and versatile. > > 73, > Geoff > GM4ESD > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: KAT100 with Ladder Line
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In reply to this post by Goody K3NG
I've been very pleased with my MFJ-974, a true balanced tuner. My
measurements of feedline current with RF ammeters indicate that overall it is as efficient as my home brew link coupled tuner with plug in coils. I've used the MFJ tuner with several combinations of feedline lengths and radiator lengths, and I've never failed to get a perfect match on all bands from 80 m to 10 m. I'd like also to mention that Dipole3.exe is an excellent, free, and very easy to use program for modeling a dipole fed with balanced line. You can play with different values of feedline length and radiator length, as well as many other parameters, to determine efficiency and impedance at the transmitter end of the feedline. One source of Dipole3.exe is http://www.smeter.net/software/dipole3.exe . Dick, K0KK On Nov 15, 2007, at 1:00 , Goody K3NG wrote: vf > Using any balun with an unbalanced tuner to feed balanced line can > be bad news (your mileage may vary, standard disclaimers apply). > Under highly reactive loads, a balun used like this can become > quite lossy. There's a couple articles in publications and on the > Internet on this, but Cebik's article is one that comes to mind > ( http://www.cebik.com/link/l-bal.html ). It's better to run a > real balanced tuner like a Johnson Matchbox, the MFJ Balanced Line > tuner, or others, if you can. > > Don Wilhelm wrote: >> Curt, >> >> There seems to be a misconception among hams that when using 450 >> ladder line, a 4:1 balun is the best thing to use. While that may >> be true in some cases, in many other cases, a 1:1 balun will serve >> better. It all depends on the feedpoint impedance of the feedline >> at the shack end, and that has little relationship with the fact >> that 450 ohm line is being used - i.e. the feedpoint impedance is >> *not* the characteristic impedance of the transmission line in >> most cases. The feedpoint impedance looking into the shack end of >> a multiband antenna can vary from extremely low to extremely high >> - it all depends on the length of the antenna and the length of >> the feedline. > -- > > Blog: http://thek3ngreport.blogspot.com/ > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Curt Milton
Please, I'd like some more discussion of this question. I've seen
before that baluns on ladder line can be lossy, but I'm not about to get a balanced tuner, so it doesn't really help. What happens if you connect the balanced line directly to the KAT100? Or, in my case, to the KAT2? I haven't had any problems so far -- maybe low power makes a big difference, or maybe I've just had antennas which were reasonable in some way. I gather it's possible to get unpleasant currents on the case, mic, or paddle. Is that exactly the condition in which the balun will be lossy? Does connecting the ground screw on the KAT2 (or the one on the balun?) alleviate the common mode current problems? Peter N8MHD _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Hi Peter,
Try not to worry too much about feeding balanced lines. Get the Elecraft BL2 and hook it to the balanced line. Connect a 2 or3 foot piece of coax from the BL2 to your rig. Tune up and away you go. If the balun tends to get a little warm, just cut off 5 or 6 feet of the balanced feedline and give it another go. You don't want to connect balanced line directly to KAT2. 73 & gl, de Joe, aa4nn ----- Original Message ----- From: "Peter Wollan" <[hidden email]> To: <[hidden email]> Sent: Friday, November 16, 2007 9:50 AM Subject: [Elecraft] Re: KAT100 with Ladder Line > Please, I'd like some more discussion of this question. I've seen > before that baluns on ladder line can be lossy, but I'm not about to > get a balanced tuner, so it doesn't really help. What happens if you > connect the balanced line directly to the KAT100? Or, in my case, to > the KAT2? I haven't had any problems so far -- maybe low power makes > a big difference, or maybe I've just had antennas which were > reasonable in some way. I gather it's possible to get unpleasant > currents on the case, mic, or paddle. Is that exactly the condition > in which the balun will be lossy? Does connecting the ground screw > on the KAT2 (or the one on the balun?) alleviate the common mode > current problems? > > Peter N8MHD > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
RE: Re: KAT100 with Ladder Line
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Peter,
I agree- my 100' fan dipole is fed with about 70' of ladder line into a current balun, which is then connected to my KAT100 through about 5' of RG-8. The balun is attached to the side of my house just outside the window and the coax brings it into the house. Since at 100w, a significant mismatch could cause the balun to heat, I made my own current balun using a pair of FT43-240 cores which has a much higher capacity than the small core used in the BL2. I followed the basic BL2 circuit diagram, replacing the switch with an external jumper so I could try it at both 1:1 and 4:1. For my antenna, the 4:1 ratio worked better - the KAT100 will get the SWR down to 1:1 on the transmitter side on all bands from 10m to 80m, and on the lower 2/3rds of 160m. I seem to have no problems getting out, having worked most of Europe (which is the direction favored by my dipole), much of South America, and most of the US & Canada on SSB. Whatever losses there are in the balun seem to be small, and more than compensated for by the use of the very low loss ladder line. Bob W1SRB -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Joe-aa4nn Sent: Friday, November 16, 2007 10:04 AM To: Peter Wollan; [hidden email] Subject: Re: [Elecraft] Re: KAT100 with Ladder Line Hi Peter, Try not to worry too much about feeding balanced lines. Get the Elecraft BL2 and hook it to the balanced line. Connect a 2 or3 foot piece of coax from the BL2 to your rig. Tune up and away you go. If the balun tends to get a little warm, just cut off 5 or 6 feet of the balanced feedline and give it another go. You don't want to connect balanced line directly to KAT2. 73 & gl, de Joe, aa4nn ----- Original Message ----- From: "Peter Wollan" <[hidden email]> To: <[hidden email]> Sent: Friday, November 16, 2007 9:50 AM Subject: [Elecraft] Re: KAT100 with Ladder Line > Please, I'd like some more discussion of this question. I've seen > before that baluns on ladder line can be lossy, but I'm not about to > get a balanced tuner, so it doesn't really help. What happens if you > connect the balanced line directly to the KAT100? Or, in my case, to > the KAT2? I haven't had any problems so far -- maybe low power makes > a big difference, or maybe I've just had antennas which were > reasonable in some way. I gather it's possible to get unpleasant > currents on the case, mic, or paddle. Is that exactly the condition > in which the balun will be lossy? Does connecting the ground screw > on the KAT2 (or the one on the balun?) alleviate the common mode > current problems? > > Peter N8MHD > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Peter Wollan
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Re: Re: KAT100 with Ladder Line
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In reply to this post by Joe-aa4nn
Hi Peter,
If I may say so I agree with Joe's suggestion to cut off a length of feeder and try again if the balun tends to get a little warm. If a balun gets warm it means that RF power is being lost to heat the balun, and assuming that the balun is not faulty the cause of the power loss is most likely that the balun does not like the load presented to it by the transmission line. If the transmission line is connected to a load such as an antenna and the length of the line is varied, measuring the impedance at the other (open) end of the line will show that the value of the resistive component R and the reactive component X (which baluns don't like in my experience) will change as the length of line is changed, also the sign of the reactive component might change (positive to negative or vice versa). The frequency (RF) is not changed during these measurements. The actual values of R and X, and the sign of X, that appear at the open end of the feeder are primarily determined by the feedpoint impedance of the antenna, the characteristic impedance of the line (e.g. 600 or 450 ohms), the loss in the line and its length. Values change more rapidly as frequency is increased for a given change in line length. On a 'flat' line where the VSWR is low, the change in R and X is very small. So if your balun runs warm, cutting off a few feet of feeder as Joe suggests could well provide a better load for the balun if the change in reactance is in the right direction, worth trying. A problem might arise on other bands though, but one solution which Lenny W2BVH reminded me of last night is to switch in different lengths of line when changing bands, which I understand works very well. I hope that this helps, and if of interest I could send you off-list an illustration of how the values of R and X can vary along a transmission line. Please contact me off list if you would like to discuss common mode current. 73, Geoff GM4ESD ----- Original Message ----- From: "Joe-aa4nn" <[hidden email]> To: "Peter Wollan" <[hidden email]>; <[hidden email]> Sent: Friday, November 16, 2007 3:04 PM Subject: Re: [Elecraft] Re: KAT100 with Ladder Line > Hi Peter, > Try not to worry too much about feeding balanced lines. > Get the Elecraft BL2 and hook it to the balanced line. > Connect a 2 or3 foot piece of coax from the BL2 to your rig <snip> > ----- Original Message ----- > From: "Peter Wollan" <[hidden email]> > To: <[hidden email]> > Sent: Friday, November 16, 2007 9:50 AM > Subject: [Elecraft] Re: KAT100 with Ladder Line > > >> Please, I'd like some more discussion of this question. I've seen >> before that baluns on ladder line can be lossy, but I'm not about to get >> a balanced tuner, so it doesn't really help. _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
RE: Re: KAT100 with Ladder Line
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In reply to this post by AC7AC
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> Nothing bad happens if you leave the balun out, Peter! > > Sometimes we over-complicate things. A balun is a good example. All that's > needed to produce a balanced "feed" is a length of transmission line (1/4 > wave or so) and a balanced load. If you have those things, it doesn't > matter > whether the output from the rig is "single ended" or "balanced", the > currents at the balanced load, such as the center of a dipole, will be > balanced. > I played around with this idea this past summer and fall (at Ron and Don's suggestion) of using an open feeder fed directly to my KAT2. I put up a 66' doublet about 30' high in some trees in my front yard. I fed it with 33' of open line I put together with wooden dowels as spacers. As you might imagine, it tuned up just fine on 40m. In fact, I could tune up fine 80m - 10m with some problems on 20m and 17m. I then made some open feeder stubs for those bands that would bring me to some 1/4 wavelength interval and then I could get them to work FB. As Ron said, it is hard to measure the efficiencies on air. All I can say is that I would wait to get my sig report and reciprocate and then tell the other station I was running 5 watts. Many times I would get a "wow - you have a great sig out here for only 5 watts". Most of the time I operated in the mid - late afternoon - mostly on 40 and 20m. Many who answered my CQ were running 75 - 100 watt stations and commented how well my K2 sounded at their QTH. I know this is all subjective - but is indicative that feeding the balanced feedline, with a little care, with the unbalanced output of a KAT2 or KAT100 can be accomplished and can be highly efficient. I did operate with the BL2 also, but running 5 watts, never noticed if I was heating up the balun or not. Not sure if I could or not. With Ron's suggestion to remove the balun (with the mindset of - why put something in the antenna system inefficient if you don't have to) it seemed to me to not only work, but work well. YMMV. So thanks, Ron, Don and others on this list. It was a fun (although not very scientific) experiment which I plan to do again when the weather warms back up in the spring. I'm also playing around with the idea of bringing an open wire feeder into my shack as well. I may play around with a balanced tuner design as well. 73, Dave W8FGU _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: Re: KAT100 with Ladder Line
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On Nov 16, 2007 2:03 PM, Dave Van Wallaghen <[hidden email]> wrote:
> > > > Nothing bad happens if you leave the balun out, Peter! > > > > Sometimes we over-complicate things. A balun is a good example. All that's > > needed to produce a balanced "feed" is a length of transmission line (1/4 > > wave or so) and a balanced load. If you have those things, it doesn't > > matter > > whether the output from the rig is "single ended" or "balanced", the > > currents at the balanced load, such as the center of a dipole, will be > > balanced. > > > > I played around with this idea this past summer and fall (at Ron and Don's > suggestion) of using an open feeder fed directly to my KAT2. I put up a 66' > doublet about 30' high in some trees in my front yard. I fed it with 33' of > open line I put together with wooden dowels as spacers. As you might > imagine, it tuned up just fine on 40m. In fact, I could tune up fine 80m - > 10m with some problems on 20m and 17m. I then made some open feeder stubs > for those bands that would bring me to some 1/4 wavelength interval and then > I could get them to work FB. Dave What I would like to know is what spacing was used on your open line feeders 0.5"(300 ohm), 0.75" (450 ohm) or 1.0" (600 ohm)? Did you use a BNC to dual banana plug connectted directly to the KAT2 on the back of the K2 or was there a short piece of coax to connect from the KAT2 to the feeders or BNC to a split banana plug. -------------------- > So thanks, Ron, Don and others on this list. It was a fun (although not very > scientific) experiment which I plan to do again when the weather warms back > up in the spring. I'm also playing around with the idea of bringing an open > wire feeder into my shack as well. I may play around with a balanced tuner > design as well. ------------------------ The design for this I like to see also. RC kc5wa ------------------------- > 73, > Dave W8FGU > > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
RE: Re: KAT100 with Ladder Line
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> Dave
> What I would like to know is what spacing was used on your open line > feeders 0.5"(300 ohm), 0.75" (450 ohm) or 1.0" (600 ohm)? Did you use > a BNC to dual banana plug connectted directly to the KAT2 on the back > of the K2 or was there a short piece of coax to connect from the KAT2 > to the feeders or BNC to a split banana plug. > -------------------- I bought 1/4" dowels from Home Depot and cut them in 3" lengths. I was using 26g wire so I drilled 1/16" holes as close to the ends as possible and then I strung the wires through the holes tying each end off to make the whole thing somewhat flat and about waist high. I spaced the dowels out every 12" or so. I then went through and dipped each end of the dowels in Plastic Dip 2-3 times each. It takes a little practice, but it is not as messy as it sounds. It secures the wire to the dowel very well. I used a small piece of Lexan I had laying around to make the apex of the antenna and secured the legs and feedline to the Lexan piece. I put the apex and legs up with 20lb test fishing line and that thing stayed up in the same spot for over 5 months. We had a cold snap and pretty good wind storm here a couple of weeks ago and a branch from one of the trees finally brought it down. I plan to repair it and take it to Alabama next week for Thanksgiving and a little op time at the in-laws. I had some BNC to RCA socket adapters around here so I took an RCA plug and soldered a 3" piece of RG174 to it and put banana sockets on the other end. I put banana plugs on my feeder. I made the stubs with banana sockets on one end and plugs on the other also. > I'm also playing around with the idea of bringing an > open > wire feeder into my shack as well. I may play around with a balanced > tuner > design as well. > ------------------------ > The design for this I like to see also. > RC kc5wa For playing around with QRP levels I was looking at a Z-Match design that is pretty popular around the net. Most are based on a design by Charles Lofgren, W6JJZ. If you do a search on Z-Match or W6JJZ, you'll find all kinds of info. I bought most of the parts I need and found some surplus plastic tuning capacitors that will work nicely. I was hoping to try it out this summer - but you all know how that time thing gets away from us :-) 73, Dave W8FGU _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: Re: KAT100 with Ladder Line
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In reply to this post by Robert 'RC' Conley
The only question left is What is "Plastic Dip". Tthis is something
I've never heard of. I have a lot of in formation on the "Z" match. A kit is available from <http://www.qrpkits.com/norcal_blt.htm> Doug Kendricks On Nov 16, 2007 3:38 PM, Dave Van Wallaghen <[hidden email]> wrote: > > Dave > > What I would like to know is what spacing was used on your open line > > feeders 0.5"(300 ohm), 0.75" (450 ohm) or 1.0" (600 ohm)? Did you use > > a BNC to dual banana plug connectted directly to the KAT2 on the back > > of the K2 or was there a short piece of coax to connect from the KAT2 > > to the feeders or BNC to a split banana plug. > > -------------------- > > I bought 1/4" dowels from Home Depot and cut them in 3" lengths. I was using > 26g wire so I drilled 1/16" holes as close to the ends as possible and then > I strung the wires through the holes tying each end off to make the whole > thing somewhat flat and about waist high. I spaced the dowels out every 12" > or so. I then went through and dipped each end of the dowels in Plastic Dip > 2-3 times each. It takes a little practice, but it is not as messy as it > sounds. It secures the wire to the dowel very well. > > I used a small piece of Lexan I had laying around to make the apex of the > antenna and secured the legs and feedline to the Lexan piece. I put the apex > and legs up with 20lb test fishing line and that thing stayed up in the same > spot for over 5 months. We had a cold snap and pretty good wind storm here a > couple of weeks ago and a branch from one of the trees finally brought it > down. I plan to repair it and take it to Alabama next week for Thanksgiving > and a little op time at the in-laws. > > I had some BNC to RCA socket adapters around here so I took an RCA plug and > soldered a 3" piece of RG174 to it and put banana sockets on the other end. > I put banana plugs on my feeder. I made the stubs with banana sockets on one > end and plugs on the other also. > > > I'm also playing around with the idea of bringing an > > open > > wire feeder into my shack as well. I may play around with a balanced > > tuner > > design as well. > > ------------------------ > > The design for this I like to see also. > > RC kc5wa > > For playing around with QRP levels I was looking at a Z-Match design that is > pretty popular around the net. Most are based on a design by Charles > Lofgren, W6JJZ. If you do a search on Z-Match or W6JJZ, you'll find all > kinds of info. I bought most of the parts I need and found some surplus > plastic tuning capacitors that will work nicely. I was hoping to try it out > this summer - but you all know how that time thing gets away from us :-) > > 73, > Dave W8FGU > > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
RE: Re: KAT100 with Ladder Line
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>
> The only question left is What is "Plastic Dip". Tthis is something > I've never heard of. > I have a lot of in formation on the "Z" match. A kit is available from > <http://www.qrpkits.com/norcal_blt.htm> Doug Kendricks > I got it at Home Depot as well. The can I have is called "Plasti Dip" it is made by a company called Perfomix. It is a multi-purpose rubber coating. I've seen it used in the past to put new rubber handles on tools as they became worn off. It is pretty flammable and vaporous. It sets up in about 30 minutes - allow 4 hours until use. It comes in a few different colors also. I don't see a price on the can I have - I want to say it was 4 or 5 bucks for a 15oz can. I did over 50 feet of feedline with around a half a can. 73, Dave W8FGU _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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