+++++++++++++++++ See also Balun Notes2 +++++++++++++++ Date: Wed, 2 May 2001 08:18:56 -0700 From: "Bahr, Casey" Subject: [Elecraft] More on air core balun Hi All, Here is some excellent information on how to properly wind an air core balun for the band(s) of interest: http://www.berkshire.net/~robbins/technote/airbalun.html The home page for this site is a must-have bookmark for any ham: http://www.berkshire.net/~robbins/technote/techref.html Casey Bahr, KS7J, K2 s/n 231 FISTS nr 3648, CC nr 450, CC/m nr 006 http://www.foreign-interests.com/k7fff ++++++++++++++++++++++++++++++++++++++++ I extracted the airbalun note and it follows.... DWN ++++++++++++++++++++++++++++++++++++++ To: n1mm at usa.pipeline.com (Tom Wagner) From: WF3T Subject: Re: How do I fix a Hy-Gain Balun? Hi Tom, Here's a copy of a prior post I think you will find very usefull. I am not familiar with the BN86 balun, but if it's not a 1:1, (ie: just a choke rather than a transformer/choke) a coax coil will not transform the impedence to 50 ohms. If it is a 1:1, study this and you'll find you want to wind your balun/choke on a piece of 4" PVC. I've used his chart to make chokes for 80 and 40 meter dipoles. Seem to work fb. 73, Steve Here's something I wrote up a while ago on coaxial balun measurements. It's a little long, but I think there's enough contesters out there building these things that it's worth posting. 73, Ed Gilbert, WA2SRQ eyg at hpnjlc.njd.hp.com --------------------------------------------------------------------- Having access to a Hewlett-Packard 4193A vector impedance meter at work, I have made measurements on a number of baluns, coaxial and otherwise. For my beams I was particularly interested how many turns and on what diameter are optimum for air core coaxial baluns, and what the effect of bunching the turns was (formless). Using the remote programming capability of the HP4193A along with an instrument controller, I measured the magnitude and phase of each balun's winding impedance at 1 MHz intervals from 1 to 35 MHz. For comparison, I also made measurements on a commercial balun which consists of a number of ferrite beads slipped over a short length of coax. I've appended some of these measurements so you can draw your own conclusions. PVC pipe was used for coil forms. The 4-1/4 inch diameter baluns were wound on thin-walled PVC labeled "4 inch sewer pipe". This material makes an excellent balun form. It's very light weight and easy to work with, and I obtained a 10 foot length at the local Home Depot for about 3 dollars. The 6-5/8 inch diameter forms are 6 inch schedule 40 PVC pipe which is much thicker, heavier, and more expensive. Each test choke was close-wound on a form as a single-layer solenoid using RG-213 and taped to hold the turns in place. The lengths of cable were cut so there was about 2 inches excess at each end. This allowed just enough wire at the ends for connections to the HP4193A's probe tip. After data was collected for each single-layer configuration, the PVC form was removed, the turns were bunched together and taped formless, and another set of measurements was taken. I have only included the "bunched" measurements in the table for one of the baluns, but the trend was the same in each case. When compared to the single-layer version of the same diameter and number of turns, the bunched baluns show a large downward shift in parallel self-resonance frequency and poor choking reactance at the higher frequencies. Interpreting the Measurements ----------------------------- All the baluns start out looking inductive at low frequencies, as indicated by the positive phase angles. As the frequency is increased, a point is reached where the capacitance between the windings forms a parallel resonance with the coil's inductance. Above this frequency, the winding reactance is reduced by this capacitance. The interwinding capacitance increases with the number of turns and the diameter of the turns, so "more is not always better". The effects of a large increase in interwinding capacitance is evident in the measurements on the balun with the bunched turns. This is probably a result of the first and last turns of the coil being much closer together than the single-layer coil. An important requirement of these baluns is that the magnitude of the winding reactance be much greater than the load impedance. In the case of a 50 ohm balanced antenna, the balun's winding impedance is effectively shunted across one half the 50 ohm load impedance, or 25 ohms. A reasonable critera for the balun's winding impedance for negligible common mode current in the shield is that it be at least 20 times this, or 500 ohms. The measurements show, for example, that 6 turns 4-1/4 inches in diameter meet this criteria from 14 to 35 MHz. The measurement data also reveals the power loss these baluns will exhibit. Each of the measurement points can be transformed from the polar format of the table to a parallel equivalent real and reactive shunt impedance. The power dissipated in the balun is then the square of the voltage across it divided by the real parallel equivalent shunt impedance. While this calculation can be made for each measurement point, an approximate number can be taken directly from the tables at the parallel resonance points. At 0 degrees phase angle the magnitude numbers are pure resistive. I didn't record the exact resonance points, but it can be seen from the tables that the four single-layer baluns are all above 15K ohms, while the ferrite bead balun read about 1.4K. These baluns see half the load voltage, so at 1500 watts to a 50 ohm load, the power dissipated in the coaxial baluns will be less than 1.3 watts, and the ferrite bead balun will dissipate about 13.4 watts (neglecting possible core saturation and other non-linear effects). These losses are certainly negligible. At 200 ohms load impedance, the losses are under 5 watts for the coaxial baluns and 53.6 watts for the ferrite beads. Conclusions ----------- - A 1:1 coaxial balun with excellent choking reactance for 10 through 20 meters can be made by winding 6 turns of RG-213 on inexpensive 4 inch PVC sewer pipe. - For 40 or 30 meters, use 12 turns of RG-213 on 4 inch PVC sewer pipe. - Don't bunch the turns together. Wind them as a single layer on a form. Bunching the turns kills the choking effect at higher frequencies. - Don't use too many turns. For example, the HyGain manuals for my 10 and 15 meter yagis both recommend 12 turns 6 inches in diameter. At the very least this is about 3 times as much coax as is needed, and these dimensions actually give less than the desired choking impedance on 10 and 15 meters. Measurements ------------ Magnitude in ohms, phase angle in degrees, as a function of frequency in Hz, for various baluns. 6 Turns 12 Turns 4 Turns 8 Turns 8 Turns Ferrite 4-1/4 in 4-1/4 in 6-5/8 in 6-5/8 in 6-5/8 in beads sngl layer sngl layer sngl layer sngl layer bunched (Aztec) ---------- ---------- ---------- ---------- ---------- ---------- Frequency Mag Phase Mag Phase Mag Phase Mag Phase Mag Phase Mag Phase 1.00E+06 26 88.1 65 89.2 26 88.3 74 89.2 94 89.3 416 78.1 2.00E+06 51 88.7 131 89.3 52 88.8 150 89.3 202 89.2 795 56.1 3.00E+06 77 88.9 200 89.4 79 89.1 232 89.3 355 88.9 1046 39.8 4.00E+06 103 89.1 273 89.5 106 89.3 324 89.4 620 88.3 1217 26.6 5.00E+06 131 89.1 356 89.4 136 89.2 436 89.3 1300 86.2 1334 14.7 6.00E+06 160 89.3 451 89.5 167 89.3 576 89.1 8530 59.9 1387 3.6 7.00E+06 190 89.4 561 89.5 201 89.4 759 89.1 2120 -81.9 1404 -5.9 8.00E+06 222 89.4 696 89.6 239 89.4 1033 88.8 1019 -85.7 1369 -15.4 9.00E+06 258 89.4 869 89.5 283 89.4 1514 87.3 681 -86.5 1295 -23.7 1.00E+07 298 89.3 1103 89.3 333 89.2 2300 83.1 518 -86.9 1210 -29.8 1.10E+07 340 89.3 1440 89.1 393 89.2 4700 73.1 418 -87.1 1123 -35.2 1.20E+07 390 89.3 1983 88.7 467 88.9 15840 -5.2 350 -87.2 1043 -39.9 1.30E+07 447 89.2 3010 87.7 556 88.3 4470 -62.6 300 -86.9 954 -42.7 1.40E+07 514 89.3 5850 85.6 675 88.3 2830 -71.6 262 -86.9 901 -45.2 1.50E+07 594 88.9 42000 44.0 834 87.5 1910 -79.9 231 -87.0 847 -48.1 1.60E+07 694 88.8 7210 -81.5 1098 86.9 1375 -84.1 203 -87.2 778 -51.8 1.70E+07 830 88.1 3250 -82.0 1651 81.8 991 -82.4 180 -86.9 684 -54.4 1.80E+07 955 86.0 2720 -76.1 1796 70.3 986 -67.2 164 -84.9 623 -45.9 1.90E+07 1203 85.4 1860 -80.1 3260 44.6 742 -71.0 145 -85.1 568 -51.2 2.00E+07 1419 85.2 1738 -83.8 3710 59.0 1123 -67.7 138 -84.5 654 -34.0 2.10E+07 1955 85.7 1368 -87.2 12940 -31.3 859 -84.3 122 -86.1 696 -49.9 2.20E+07 3010 83.9 1133 -87.8 3620 -77.5 708 -86.1 107 -85.9 631 -54.8 2.30E+07 6380 76.8 955 -88.0 2050 -83.0 613 -86.9 94 -85.5 584 -57.4 2.40E+07 15980 -29.6 807 -86.3 1440 -84.6 535 -86.3 82 -85.0 536 -58.8 2.50E+07 5230 -56.7 754 -82.2 1099 -84.1 466 -84.1 70 -84.3 485 -59.2 2.60E+07 3210 -78.9 682 -86.4 967 -83.4 467 -81.6 60 -82.7 481 -56.2 2.70E+07 2000 -84.4 578 -87.3 809 -86.5 419 -85.5 49 -81.7 463 -60.5 2.80E+07 1426 -85.6 483 -86.5 685 -87.1 364 -86.2 38 -79.6 425 -62.5 2.90E+07 1074 -85.1 383 -84.1 590 -87.3 308 -85.6 28 -75.2 387 -63.8 3.00E+07 840 -83.2 287 -75.0 508 -87.0 244 -82.1 18 -66.3 346 -64.4 3.10E+07 661 -81.7 188 -52.3 442 -85.7 174 -69.9 9 -34.3 305 -64.3 3.20E+07 484 -78.2 258 20.4 385 -83.6 155 -18.0 11 37.2 263 -63.2 3.30E+07 335 -41.4 1162 -13.5 326 -78.2 569 -0.3 21 63.6 212 -58.0 3.40E+07 607 -32.2 839 -45.9 316 -63.4 716 -57.6 32 71.4 183 -40.5 3.50E+07 705 -58.2 564 -56.3 379 -69.5 513 -72.5 46 76.0 235 -29.6 *\* steve.steltzer at paonline.com (WF3T) *\* *\* Harley Davidson Inc. *\* +++++++++++++++++++++++++++++++++++++++++++++++++++ Date: Mon, 16 Jul 2001 11:16:22 -0700 From: "Ron D' Eau Claire" Subject: RE: [Elecraft] Balun for KAT1 Greg, KI8AF asked: >Does anyone have a really simple plan for a > balun. > Presently have the 40 and 20 band filter but plan to expand to maybe > 30 > and 17 in the futrue. Would be nice to have a very small, portable > balun > to cover these bands. Asking to much?? It's no trick to build a balun that will cover 1.8 to 30 MHz and work well. Baluns are quite broadband when used properly. What they do NOT do well is handle extreme impedances. Virtually every balun you will encounter from normal sources is designed to look into a 50 ohm non-reactive load on one side, and either 50 or 300 ohms non-reactive on the other side. That means they are used in a feeder with a very low (1:1 ideally) SWR on it. "Non-resonant" antennas with so-called 'tuned' feeders tend to present extreme impedances to the balun on one band or another, depending upon their size. You can get away with using a balun with higher SWR's. It depends upon how high the SWR gets. At some point the balun starts acting more like a dummy load than a balun, and your rig will seem to be happily feeding power into the antenna, when it is actually feeding power into the balun-dummy load. That said, many operators, including me, have done it and gotten away with it. It's a bit hard to predict just what will happen at higher SWR's and it's not easy to know how efficiently the balun is working. If the balun starts arcing or if it has a torodial core and that gets hot or breaks, you can be sure the balun is being misused. Unfortunately, you can throw away virtually all of 5 watts in a balun and never know it. That's not normally enough to make them arc or fracture a core. Probably the best practice is to use the most robust balun you can lay your hands on. A big core will handle larger magnetic fields produced by high currents in the windings better, and the bigger spacing of turns and better insulation will help avoid leakage losses when the voltages are high. Amidon makes a nice balun "kit" that sells for less than $10. See http://www.bytemark.com/amidon/kit_bal1.htm for more info. You will notice that it is rated for a kilowatt. That's assuming it is used in a FLAT feedline (1:1 SWR). It probably represents a good investment in capacity if you are going to use it with an ATU feeding some sort of tuned feedline. The kit consists of a toroidal core about 2 inches in diameter, some heavy duty magnet wire to wrap on it and instructions. Personally, I'd avoid a balun in the field if I could. Use an end fed wire against a 1/4 wave 'counterpoise' connected to the case or a simple dipole. Since the K1 is a two-band rig, two dipoles, one for each band, connected to the same feedline would probably be my first choice. While that works 'best' if the bands are harmonically-related (say 40 and 20 meters) you can still use that trick on just about any set of bands you choose. You can even make the radiator out of a half wave of twin lead, cutting the second wire short to make a 1/2 wave for the higher-frequency antenna. That way you only have to string up one 'radiator'. The SWR on the feedline will be significant, but if you use good feedline (no tiny RG-174) the losses in a reasonable length won't be great and the K1's ATU should be able to tune it easily. You can even go to four bands that way, if you are willing to deal with two lengths of twin lead each containing two radiators, or you might have two antennas matching the band pairs you choose. Ron AC7AC K2 # 128 ++++++++++++++++++++++++ Date: Mon, 16 Jul 2001 21:18:19 -0700 From: lhlousek Subject: Re: [Elecraft] Balun for KAT1 <<>> Go to the "Builders resources" page, then "KAT2 tuner notes", then "Balun transformer links". Lou W7DZN +++++++++++++++++++++++++++ Date: Mon, 16 Jul 2001 21:25:54 -0700 From: Eric Swartz WA6HHQ - Elecraft Subject: Re: [Elecraft] Balun for KAT1 Try this link: http://www.elecraft.com/Apps/balun_transformer_links.htm In general, you can search for 'balun' using our search box on the main Elecraft page. 73, Eric WA6HHQ ++++++++++++++++++++++++++++++ Date: Tue, 17 Jul 2001 20:17:32 -0500 From: Bill Stietenroth Subject: [Elecraft] re: Balun for K1 or K2 There is no reason to make things complicated trying to use a 4:1transformer type balun. You never know from one time to the next what the impedence at the input of the feed line will be if you are using multi-band dipole and long wire type antennas. I have had great sucess using a W2DU choke balun on my K2. I regularly hook it up to a ladder line fed 140' dipole or a 165' long wire and countepoise. I made it out of a short piece of RG8X mini and 8 Amidon FB77-5621 beads. I put a BNC on the input end. On the other end I made a 2" long lead out of the coax shield and a 2" long center conducter lead and put ring tongue connectors on the end of each. Slide the beads right down against the two 2" leads and put some shrink tubing over them to hold them there. With a small round head machine screw and a wing nut that stays attached to each lead, I can hook up to just about any kind of antenna. The 8 beads work fine down thru 80 meters, with essentially no current on the outside of the shield. No reactance like a coil wound transformer type of balun, no losses or distortion from core saturation. The autotuner has tuned everything that I hook to it. Bill, K5ZTY Houston,TX +++++++++++++++++++++++++++ Date: Tue, 17 Jul 2001 14:27:22 -0400 From: "Steve Lawrence" Subject: RE: [Elecraft] Balun for KAT1 Because of the issues associated with a transformer based balun, I decided upon using a W2DU style choke type balun for my portable operation. While typically available at only a 1:1 ratio, I reasoned the main purpose was to keep stray RF out of the tuner and off of the K2 chassis -- let the tuner provide the match to the load not a transforming balun. I built the balun from a kit from "the wireman" (www.thewireman.com) and purchased at the Dayton Hamventon. The kit consists of about 1 ft. of Teflon insulated coax (RG303U), and 50 ferrite beads -- an over design for QRP as it will handle 1KW. I mounted the ferrite bead covered coax in a box and fitted a BNC input and banana jack output (to a ladder line fed dipole). The balun went between KAT2 tuner and antenna feedline. While tested satisfactorily in portable operation, I have no way of measuring losses or effectiveness. I made a dozen SSB contacts into Europe on my K2 during the weekend on the 40M dipole up about 20 ft. It's not the smallest/lightest solution, but ultimate portability wasn't the goal (it is smaller than the typical 1KW toroidal based balun however). If I could come up with a smaller/lighter design better suited for QRP power levels, so much the better. Better still... a multi-band antenna design that doesn't require a balun. But those experiments remain to be done here... sometime... 73, Steve aa8af K2 #2033 +++++++++++++++++++++++++++++++++++ "Ron D' Eau Claire" Sent by: owner-elecraft at qth.net 07/16/2001 02:16 PM Please respond to "Ron D' Eau Claire" To: cc: Subject: RE: [Elecraft] Balun for KAT1 Greg, KI8AF asked: >Does anyone have a really simple plan for a > balun. > Presently have the 40 and 20 band filter but plan to expand to maybe > 30 > and 17 in the futrue. Would be nice to have a very small, portable > balun > to cover these bands. Asking to much?? It's no trick to build a balun that will cover 1.8 to 30 MHz and work well. Baluns are quite broadband when used properly. What they do NOT do well is handle extreme impedances. Virtually every balun you will encounter from normal sources is designed to look into a 50 ohm non-reactive load on one side, and either 50 or 300 ohms non-reactive on the other side. That means they are used in a feeder with a very low (1:1 ideally) SWR on it. "Non-resonant" antennas with so-called 'tuned' feeders tend to present extreme impedances to the balun on one band or another, depending upon their size. You can get away with using a balun with higher SWR's. It depends upon how high the SWR gets. At some point the balun starts acting more like a dummy load than a balun, and your rig will seem to be happily feeding power into the antenna, when it is actually feeding power into the balun-dummy load. That said, many operators, including me, have done it and gotten away with it. It's a bit hard to predict just what will happen at higher SWR's and it's not easy to know how efficiently the balun is working. If the balun starts arcing or if it has a torodial core and that gets hot or breaks, you can be sure the balun is being misused. Unfortunately, you can throw away virtually all of 5 watts in a balun and never know it. That's not normally enough to make them arc or fracture a core. Probably the best practice is to use the most robust balun you can lay your hands on. A big core will handle larger magnetic fields produced by high currents in the windings better, and the bigger spacing of turns and better insulation will help avoid leakage losses when the voltages are high. Amidon makes a nice balun "kit" that sells for less than $10. See http://www.bytemark.com/amidon/kit_bal1.htm for more info. You will notice that it is rated for a kilowatt. That's assuming it is used in a FLAT feedline (1:1 SWR). It probably represents a good investment in capacity if you are going to use it with an ATU feeding some sort of tuned feedline. The kit consists of a toroidal core about 2 inches in diameter, some heavy duty magnet wire to wrap on it and instructions. Personally, I'd avoid a balun in the field if I could. Use an end fed wire against a 1/4 wave 'counterpoise' connected to the case or a simple dipole. Since the K1 is a two-band rig, two dipoles, one for each band, connected to the same feedline would probably be my first choice. While that works 'best' if the bands are harmonically-related (say 40 and 20 meters) you can still use that trick on just about any set of bands you choose. You can even make the radiator out of a half wave of twin lead, cutting the second wire short to make a 1/2 wave for the higher-frequency antenna. That way you only have to string up one 'radiator'. The SWR on the feedline will be significant, but if you use good feedline (no tiny RG-174) the losses in a reasonable length won't be great and the K1's ATU should be able to tune it easily. You can even go to four bands that way, if you are willing to deal with two lengths of twin lead each containing two radiators, or you might have two antennas matching the band pairs you choose. Ron AC7AC K2 # 1289 ++++++++++++++++++++++++++++++++ Date: Thu, 19 Jul 2001 12:03:16 -0500 From: "benlightnd1" Subject: [Elecraft] A neat little balun For those of you who are questioning what you will use as an antenna in the field and think you may need a balun, check out Jameco's catalog ( page 61 ) or go to their home page and type "balun" or 72637 into their search engine. This is a small balun that converts BNC connectors to ladder line with a 100 ohm termination. weight is 0.1 lbs. Might be just what you need!! The only problem with this one???? You didn't get to build it!! Hee Hee 73 to all Jerry N0JRN ++++++++++++++++++++++++++++ Date: Fri, 20 Jul 2001 09:38:50 -0500 From: "Timothy A. Raymer" Subject: Re: [Elecraft] A neat little balun Craig, No, they (some of them, anyway) REALLY are Baluns!! They were designed for IBM 3270 Coaxial connected Terminals to be attached to 100ohm UTP. I have taken some apart, and some have a true 1:1 balun, and some have just a single-sided configuration (almost like a fixed auto-transformer.) the frequency was fairly low, so they should have good performance on the lower bands. Your mileage may vary, as I have not fired one up in this configuration to test it yet. I will rummage my wiring closet and see if I can find my stash to examine them for more information. If you are lucky enough to have some old THICKNET terminators in the closet, the make GREAT 5W dummy loads. The little ones can get zapped with more than a watt or two. Tim Raymer 73 de KA0OUV At 23:33 07/19/01 -0400, K4IA at aol.com wrote: >It is page 66 of my May-July catalog. > >I am not familiar with computer networking cables but I do know the old coax >kind are "terminated" with a 50 ohm resistor when there is no further place >for them to go. Is there any chance that 100 ohm termination is some kind of >resistor and not the output impedance? > >Radio K4IA >Craig Buck ++++++++++++++++++++++++ Date: Fri, 20 Jul 2001 22:09:43 -0400 From: Charles Greene Subject: RE: [Elecraft] A neat little balun At 02:38 PM 7/20/2001 -0700, Ron D' Eau Claire wrote: >Steve wrote: > > The size and construction would concern me for transmitting > > purposes. What > > are the losses? Frequency response? Someone with a network analyzer > > could look at this in a lab, but until them, I'm sticking with baluns > > designed for transmitting. I'm currently using a W2DU choke type balun. > >Those are excellent questions. > >Like ANY coil on a toroid, it is very important that the core be able to >handle the magnetic flux created by the windings. The more current flowing >in the winding the more magnetic flux the core must handle. Current is, of >course, determined by both the power being run and the impedance of the >circuit connected to the balun. Two or three watts of r-f can generate a >very significant current when feeding a low impedance antenna. > >At the other extreme, how high of a voltage can a little balun handle >without arcing? Again it is a matter of both the impedance presented to the >balun by the feedline and the power being fed into it. > >Both scenarios point to a physically small balun being very limited in the >range of impedances and powers it can handle. > >A network analyzer might help, but there is still the issue of what happens >when more than a few milliwatts is fed into the balun. Once the core >saturates with magnetic flux, the electrical characteristics of the balun >change dramatically for the worst. That's why I recommend the largest balun >you are willing to carry around, particularly if one plans to use it at the >output of the ATU in a system with a high SWR. The most important thing in a small balun is its efficiency. If it were 100% efficient, you could run very high power to a tiny balun. The power for core saturation is very high and usually will not occur before heating due to total losses becomes a factor. The majority of the losses in a balun are of the dielectric type as opposed to core heating or ohmic losses, so it is important to use high quality materials. I have had good luck with stranded silver plated teflon insulated wire. I have tested some baluns I have made using FT50 (1/2") cores at 100 watts without them even getting warm. Their losses are on the order of 0.1%. You have to select a material that will cover the frequency range you want and still have a high efficiency. The 61 ferrite material is has high efficiency and a medium permeability (125) and is good for the high end of the HF band in the 0.5" size. Use a larger size (82, 114 or 140) for the lower frequencies. The type 43 material has more permeability (850) but is not quite so efficient. You need to keep the voltage within reason too - a SWR of 5:1 is reasonable. The current baluns have a frequency range of nearly twice that of the voltage baluns but are more complicated to wind. I have built volt baluns that cover 80-10, or 160-15 but never 160-10. On the other hand, a good current balun will cover 1 to 30 MHz. To get enough inductance with a powdered iron core, material type 2, you have to have a large size core. If that is ok, I found the T-184-2 to be a good core to work with. I haven't found the type 2 powdered iron cores offer any advantage in efficiency or ability to work with higher SWRs in the larger baluns contrary to common folk lore. So I just stick with the ferrite cores which can be smaller with fewer turns. There are some links to baluns on the Elecraft web site and some are of excellent quality and are really easy to build. 73, Chas, W1CG ++++++++++++++++++++++++++ Date: Sun, 18 Nov 2001 14:57:01 -0700 From: "James R. Duffey" To: , qrp-l Subject: [112102] 1:1 Baluns Voltage or Current? Message-ID: Mime-version: 1.0 Content-type: text/plain; charset="US-ASCII" Content-transfer-encoding: 7bit Bob - Your questions have been raised (and answered) here before: "So far I have yet seen any professional writing against the 1.1 Voltage balun.(except on radio works site) Are there really losses with that balun?" The definitive work comparing 1:1 current baluns and voltage baluns is: Roy W. Lewallen, W7EL, "Baluns: What They Do and How They Do it" page 157 "The ARRL Compendium Volume 1" Roy coined the words voltage and current balun in this article. Anybody who wants to know about 1:1 baluns in practical use should read this article. The book is still in print and should be available from ARRL or your local bookstore; ISBN: 0-87259-019-4. It has lots of other useful articles as well. The article tests the balun's effectiveness in practical use at forcing balanced currents in the antenna and feedline fed. Lewallen's measurements showed that the current balun was more effective in forcing a balnce than the voltage balun. Although this article is often quoted (mistakenly) as saying the voltage balun does not work, Roy says no such thing in the article. In fact, some of his measurements show that the voltage baluns do work, that is they improve the balance of feedline and/or antenna currents. They just don't do it as well as a current balun. Bottom line (my interpretation) is that if you are building a new antenna system or upgrading an old one, install or replace the voltage balun with a current one. If you have a dipole that is working OK with a voltage balun, it probably isn't worth the work to replace it; that is the money spent on a new balun could probably be better spent other places. But if you have the antenna down for maintenence, think about replacing the voltage balun with a current one. There are two other references that address the voltage vs. current balun issue: "Building and Usin Baluns and Ununs", by Jerry Sevick, W2FMI, ISBN: 0-943016-09-6 And "Reflections" (either I or II) by Walt Maxwell W2DU I find W7EL's treatment more accessible than either of the above. W7EL does not address losses, but Sevick does. Losses have more to do with the proper application and design of a balun than with the type. Most voltage baluns designed for amatuer use have problems, including measureable mismatches and imbalances at both the high and low ends of the HF spectrum. These can lead to losses. The commercial 1:1 baluns marketed by W2AU and VanGorden probably have excessive losses on 80 M and 160 M , but are probably OK, but not great, from a loss standpoint on 40 M to 10 M. The losses are probably on the order of a few tenths of a dB, and not significant enough to be concerned for QRP use. But a current balun is not a guarantee of low losses. Some of the bead baluns popularized by W2DU use high permeability ferrite beads which are also relatively high loss. In the parlance of magnetics they have a high loss tangent. Again, this is more of a concern for QRO use than for QRP use. A few tenths of dBs dissipated in a bead balun used at the 5 W level is unnoticeable, at the 1500 W level a few tenths of dBs amount to a few watts, and significant heating can result. In short, if you are building a new antenna system, use a good current balun. If you have an antenna with a voltage balun, I wouldn't replace it until you need to, or do other antenna maintenence work. I wouldn't buy a new voltage balun, but I wouldn't hesitate to use a properly operating antenna system that incorporated one. I have posted this information on QRP-L before. Things haven't changed much. Recent editions of the ARRL Handbook also champion current baluns over voltage baluns. The information is out there. Radioworks may be a bit strident and parochial in pushing their current baluns, but the basic physics of the matter points one in that direction as well. I hope that this helps. - Dr. Megacycle KK6MC/5 "Radio Green Chile" -- James R. Duffey KK6MC/5 30 Casa Loma Road Cedar Crest, NM 87008 +++++++++++++++++++ Date: Wed, 10 Apr 2002 15:40:18 -0400 From: "Ed Tanton" To: "'Low Power Amateur Radio Discussion'" Subject: [124332] FW: [Lowfer] Triflier Core Winding Although this originated on [Lowfer], I think Frank's results are well worth publishing here... since this answers a question I have had for some time about wideband transformer winding methods. 73 Ed Tanton N4XY Ed Tanton N4XY 189 Pioneer Trail Marietta, GA 30068-3466 website: http://www.n4xy.com All emails & checked by Norton AntiVirus with AutoProtect LM: ARRL QCWA AMSAT & INDEXA; SEDXC NCDXA GACW QRP-ARCI OK-QRP QRP-L #758 K2 (FT) #00057 =20 -----Original Message----- From: lowfer-admin at mailman.qth.net [mailto:lowfer-admin at mailman.qth.net] On Behalf Of Frank Gentges K=D8BRA Sent: Wednesday, April 10, 2002 10:18 AM To: lowfer at mailman.qth.net; lowfer at mailman.qth.net Subject: Re: [Lowfer] Triflier Core Winding Peter, I built two wideband transformers just the same except one was trifilar and=20 the other was just 3 separate windings. The one with separate windings=20 went from 10 kHz to 10 MHz. The trifilar one went from 10 kHz to 30 MHz. I concluded that the trifilar, or bifilar for that matter, got the windings=20 more closely coupled and reduced the leakage reactance between them and=20 extended the top end of a wideband transformer about 1.5 times. Frank K0BRA At 09:01 AM 4/10/02 -0500, Peter Barick wrote: >Loafers, > >I'm trying in vain to find information on the practice of "trifiler"=20 >winding, as used on a ferrite core. > >Why is it used? It seems to be a similar in style to Litz wire, the=20 >forming of a twisted 3-wire conductor and wrapping it on the core,=20 >where all like ends are tied together. This technique is new for me.=20 >I've seen it where the three comprised both input and output windings,=20 >however. > >I don't think it's to increase current cap., as the ref. I have is for=20 >receiving apps. Then could it be for flexibility for winging on a small >core? Don't think that's it. Stumped. > >Does anyone know of a forum better able to answer this question? > >Peter > > >_______________________________________________ >Lowfer mailing list >Lowfer at mailman.qth.net http://mailman.qth.net/mailman/listinfo/lowfer Frank Gentges K=D8BRA LF web site at _______________________________________________ Lowfer mailing list Lowfer at mailman.qth.net http://mailman.qth.net/mailman/listinfo/lowfer ++++++++++++++++++ Date: Wed, 10 Apr 2002 13:12:19 -0400 From: "Tracy Markham" To: "QRP-L" , Subject: [124334] RE: [Lowfer] Triflier Core Winding There are several books that talk about the third winding, whether it is grounded or 'floating' ... the interconnections determine the ratio, and the spacing of the conductors in the transmission line determine the 'characteristic impedances.' Check "Transmission Line Transformers" by Dr Jerry Sevick, W2FMI, he goes into great detail and gives all the math to support his discussion and to be able to design your own. Of course, I sell that book (plug without shame) Tracy N4LGH (CWS ByteMark) www.cwsbytemark.com www.bytemark.com ++++++++++++++++++ Date: Wed, 17 Apr 2002 19:45:09 -0400 To: elecraft at mailman.qth.net From: Charles Greene Subject: [Elecraft] Low Power Balun Kit Hi All, The NJQRP Club is offering a low power 4:1 current balun kit. See: http://www.njqrp.org/balun It works fine with my K2 and K2AT and also with my 100 watt rig and Z11 antenna tuner for feeding a balanced line. ++++++++++++++++++ From: "George Heron N2APB" To: "NoVAQRP" , "NJQRP" , "QRP-L" , Subject: [124755] Low Power Balun Kit is available As announced at Atlanticon last weekend, and in the recaps here on the lists, the NJQRP Club has kitted the Low Power Balun design of Chas Greene, W1CG. Not your everyday balun, the W1CG Low Power Balun has been meticulously optimized and tested to ensure top performance at QRP power levels. Chas is an excellent engineer and has described the theory, design considerations and construction detail in the companion manual that will be of great value to all who build and use the balun. Chas also authored an article concerning this project in the next issue of QRP Homebrewer, coming to subscribers in April. "The open wire balanced transmission line is widely used on wire antennas in an attempt to reduce losses and unwanted radiation from the transmission line and as a small lightweight alternative to coax for portable use. It benefits from a balun (BALanced to UNbalanced device) to convert the unbalanced output from an antenna tuner to the balanced input of the transmission line. The operator who wants a small, lightweight balun for back packing or fix station use for low power or QRP operation doesn't have much choice. Either he buys a large, heavy commercial balun or he searches the Internet for the design of a home brew balun, which likely has unknown performance. To help fill this void, this kit concerns a small, low power 4:1 current balun that is easy to build and has good performance from 160 through 10 meters. A 4:1 balun is a good match for feeding an Off-Center-Fed antenna and performs well feeding an open wire transmission line, so that is the type presented." You can see several photos and the ordering information on the NJQRP website at http://www.njqrp.org/balun 73, George N2APB n2apb at amsat.org & Joe N2CX n2cx at voicenet.com for the NJQRP club at http://www.njqrp.org +++++++++++++++++++ Date: Fri, 31 May 2002 13:03:58 -0400 From: "Mark J. Dulcey" To: k6iii at juno.com Cc: elecraft at mailman.qth.net Subject: Re: [Elecraft] Baluns - give me a kit! k6iii at juno.com wrote: > Eric/Wayne, > > Baluns are a bit of a mystery to me... I'm pretty simple minded, now, but > know there is a need for 4:1 and even 6:1 baluns (and others) with these > QRP rigs. I see articles on making these, but the parts are usually not > readily available. If Radio Shack (Tandy) has the parts please let me > know what to get (i.e. RS part number, etc...). Sure, the KAT1 or KAT2 > auto antenna tuners will probably match any antenna I string up, but > wouldn't it be better to at least get close to the 50-ohm impedance that > the K1/K2 want to see? Maybe I'm missing something here, but... > > It seems to me it would simple thing to market a do-it-yourself balun > kit. I suspect Elecraft has all the parts and could kit up a core with > some wire, maybe a box and a couple of connectors along with some > instruction sheet on how to wind various baluns for QRP (use with K1's > and K2's). Why not include a discusson in these instruction sheet about > baluns and when you need to use them, along with a few simple wire > antenna examples, etc... > > I would imagine that you would sell quite a few of these balun kits. Elecraft may not have such a kit, but the New Jersey QRP Club (NJQRP) does: http://www.njqrp.org/balun/index.html ++++++++++++++++++ From: "John Crux" To: Date: Fri, 5 Jul 2002 10:31:54 +0100 Subject: [Elecraft] Balun inside K2 ... digest #200 msg 1 I have built two LDG AT11 tuners. I would not like to try putting a half decent balun into either my K2 or into the standard LDG case, or even into the home brew case I used for the first AT11. I have made several 4:1 baluns. One was on a T-200 powdered iron core and I made it for use with my AT11 by a UK foundation licensee, at his legal limit of only 10 watts RF. It was marginal on 40m and useless on 80m (not enough inductance ?) So I swapped it for the humongous ferrite core balun (SIX 2.4 inch ferrite cores) the partly assembled guts of which I found on the Dayton flea market. If Jerry Sevick (see below) is right this item will probably handle 20 kW. Small it is not. Maybe an overkill for 10w. But it sure works down to 160m ! Before trying to squeeze a tiny balun into either the K2 or the LDG, I suggest asking if your journey is really necessary. From the literature (mostly the article by Jerry Sevick W2FMI in CQ, November 1993 page 50) its not trivial getting adequate performance, especially from a small enough-to-fit-the-space toroid. Greater flexibility (and efficiency) is probably achieved by using an external balun whenever you need one. Cut your losses. There is a CWS ByteMark kit with a 2.4 inch ferrite core that should do the trick. Or I'd use a large powdered iron core, like a T-300D. Small is not always beautiful .. P.S. Wayne & Eric - assuming the KAT-100 will be designed to fit into the EC-2, there should be room for a nice BIG balun, if anyone wants one. John G3JAG K2 #609 into a few feet of RG-8, a Centaur balun (2 stacked ferrite cores) and lots of ladderline. Over 250 countries worked with a 40m dipole. +++++++++++++++++ Date: Thu, 04 Jul 2002 10:22:49 -0500 From: "John A. Rodenbarger" To: elecraft at mailman.qth.net Subject: Re: [Elecraft] Balun inside K2 ... digest #200 msg 1 I'm wondering, too. As soon as George gets some more parts in and another "run" ready to ship, I guess I'll find out. I used some 1K-rated baluns that I built from Amidon "kits" (core, wire, and a hard-to-read xeroxed sheet) for FD and was happy w/them. 73, John WB9OFG Alan Fryer wrote: > Wonder how the W1CG balun kit offered by the NJQRP Club stacks up ? > > Alan, N3BJ +++++++++++++++++++ Date: Thu, 04 Jul 2002 12:00:42 -0400 To: "John Crux" From: Charles Greene Subject: Re: [Elecraft] Balun inside K2 Cc: Hi John and All, Earlier I had some discussions with Wayne about putting a balun inside the K2 and using the two holes in the back of the K2 for output connectors, but it ended up with us both agreeing that it was better to put it outside. Wayne is still trying to figure out what to do with the two holes in the back of the K2. I agree that you need a large core(s) to build a successful Voltage balun. See page 34 of Sevick's book, "Building and Using Baluns and Ununs" He describes an excellent balun, good for the legal limit using 21 turns on two T400-2 cores. There's a reason for this. The -2 material makes the best voltage balun, but you need a lot of core material to get adequate inductance. I have been unsuccessful building a low power >100 watts 4:1 voltage balun. Using cores from F114-43 to T187-2, if I use turns to get enough inductance for good performance on 160 meters, the high frequency performance suffers. Typical performance is 1.8 MHz through 19 MHz, or 3.5 MHz through 30 MHz. I am using same the criteria Sevick uses to define good performance which is basically a reasonable SWR into a balanced 200 ohm load. I don't know about the LDG kit. However, I have built many good performance 4:1 and 1:1 current baluns. See: http://www.njqrp.org/balun/index.html for a low power 4:1 current balun kit that has excellent performance, designed by yours truly. Here again, I wouldn't try to put it in my K2. At 10:31 AM 7/5/2002 +0100, John Crux wrote: >I have built two LDG AT11 tuners. I would not like to try putting a >half decent balun into either my K2 or into the standard LDG case, or >even into the home brew case I used for the first AT11. -- snip -- ++++++++++++++++++ From: "Wilton, Paul" To: "'elecraft at mailman.qth.net'" Subject: Re: [Elecraft] Balun inside K2 ... digest #200 msg 1 Date: Fri, 5 Jul 2002 09:20:39 +0100 Re >From: "Alan Fryer" >To: elecraft at mailman.qth.net >Subject: Re: [Elecraft] Balun inside K2 ... digest #200 msg 1 >Date: Thu, 04 Jul 2002 12:54:39 +0000 > >Wonder how the W1CG balun kit offered by the NJQRP Club stacks up ? > >Alan, N3BJ I built one of these a couple of months ago and am very pleased with its performance. Using my K2/KAT2 as the SWR meter I have found it to be a good SWR 1:1 match from 80m to 10m into a 200ohm load. In practice, I am using it with an OCF dipole 20m long and have found a "before" ATU SWR of between 1:1.5 and 1:7 for all bands from 80m to 10m. My KAT2 then takes care of the residual SWR. At $15, its a lot cheaper than a commercial 1:4 balun. Paul Wilton M1CNK/M3CNK K2#2546 ++++++++++++++++ To: Ken Knecht Cc: elecraft at mailman.qth.net Subject: Re: [Elecraft] OT - Balun book? From: "Steve Lawrence" Date: Thu, 14 Nov 2002 10:29:08 -0500 Ken, Check out "Building and Using Balusn and Ununs: Practical Designs for the Experimenter" by Jerry Sevick, W2FMI. It's available: http://www.bytemark.com/products/books1.htm along with other references on the topic in general. Bytemark also stocks cores and other related stuff... 73, Steve aa8af Ken Knecht Sent by: elecraft-admin at mailman.qth.net 11/14/2002 09:18 AM To: elecraft at mailman.qth.net cc: Subject: [Elecraft] OT - Balun book? Xmas time! I'm looking for the title and author of a good in-print book on baluns so my sister can surprise me with it on Xmas morn. Suggestions? Ken +++++++++++++++++++