++++++++++++++++++++++++++++ Date: Mon, 30 Apr 2001 21:32:59 -0400 From: "Jim Worthington" Subject: RE: [Elecraft] balanced tuner > Any recommendations for a homebrew blanched tuner. I'm very partial to the Emtech ZM-2. It's very compact, is naturally balanced (but works well with coax, too), is very quick tuning and includes an SWR indicator. It's a $50 kit (see http://emtech.steadynet.com/zmdesc.htm ). If you want to homebrew a similar tuner (Z match) see http://www.pconline.com/~rohrwerk/k0jd/z-match.html . On the other hand, I've used three different unbalanced tuners with baluns (MFJ-949E, Ameritron ATR-30 and Elecraft KAT2 + LDG balun) on balanced line without problems. I'd look at other possibilities before replacing the tuner. Sniffing around the shack for RF with a field strength meter may reveal the problem. Good luck, - - Jim, AD4J ++++++++++++++++++++++++++++++++++ Date: Tue, 1 May 2001 00:34:24 EDT From: N2EY at aol.com Subject: Re: [Elecraft] balanced tuner In a message dated 4/30/01 8:41:25 PM Eastern Daylight Time, aturner13 at triad.rr.com writes: > Several people mentioned using a balanced tuner as opposed to the MFJ with > 4:1 balun to match the dipole fed with ladder line. > Any recommendations for a homebrew blanched tuner. I hate to lay out a lot > of money for one since I think this may be my last adventure with using > ladder line, unless I can get one outside and up in the air. > The definitive article on this subject was in QST in 1990 (February, I think). It was written by R.L.Measures, AG6K, and develops both the practical and theoretical basis for a design. Most "modern" tuners consist of a single-ended matching network followed by a toroid-core balun. The problem with this idea is that many real-world situations present the balun with loads that are far from its design impedance. For example, a 4:1 balun that was designed to work with resitive loads of 200 and 50 ohms may not behave very well when presented with a load of 12 + j400 on the 200 ohms side. Solution is to put the balun on the rig side, then build a balanced-to-balanced matching network. AG6K shows how to do this with just one variable cap and two ganged roller coils. 73 de Jim, N2EY +++++++++++++++++++++++++++++++++++++++++++ Date: Tue, 01 May 2001 08:32:39 -0400 From: Charles Greene Subject: Re: [Elecraft] balanced tuner At 08:42 PM 4/30/2001 -0400, Alex wrote: >Several people mentioned using a balanced tuner as opposed to the MFJ with >4:1 balun to match the dipole fed with ladder line. >Any recommendations for a homebrew blanched tuner. I hate to lay out a lot >of money for one since I think this may be my last adventure with using >ladder line, unless I can get one outside and up in the air. > >Alex - N4BYJ Try to buy an used Johnson Matchbox. 73, Chas, W1CG +++++++++++++++++++++++++++++++++++++++++++++ Date: Tue, 1 May 2001 06:29:02 -0700 From: Kevin Swesey Subject: RE: [Elecraft] balanced tuner Alex, if you like portable operation, you can't beat the BLT (Balanced Line Tuner) offered by NorCal on their website. Only $25.00 or so and a nice little tuner. http://www.fix.net/~jparker/norcal.html '73 Kevin Swesey, K6RXL kevin.swesey at sigtech.com ++++++++++++++++++++++++++++++++++++++++++++++ Date: Tue, 01 May 2001 07:13:49 -0700 From: Phil Wheeler Subject: Re: [Elecraft] balanced tuner Kevin Swesey wrote: > > Alex, if you like portable operation, you can't beat the BLT (Balanced Line > Tuner) offered by NorCal on their website. Only $25.00 or so and a nice > little tuner. > Actually, you can "beat" the BLT. It is a great value for the price. But it is designed for 40-10 meters and so advertized. I've found the ZM-2 to be more capable and tune almost anything I use. At $50, the ZM-2 is a great value. But for the K1 or K2, the internal tuners (KAT1 and KAT2) are the way to go. They not only perform well, but are very convenient for portable ops (reduced cabling, weight and increased convenience). Phil W7OX ++++++++++++++++++++++++++++++++++++++++++++++++ Date: Tue, 1 May 2001 07:20:24 -0700 (PDT) From: Jim Apple Subject: Re: [Elecraft] balanced tuner Here is the AG6K article http://www.vcnet.com/measures/bbat.html And a commerical version http://airwaterkinginc.purification.com/BlissZMatchMaster.htm ===== - - Jim Apple (WB1DOG) ++++++++++++++++++++++++++++++++ From: "Alex" To: Sent: Tuesday, May 01, 2001 2:42 AM Subject: [Elecraft] balanced tuner > Several people mentioned using a balanced tuner as opposed to the MFJ with > 4:1 balun to match the dipole fed with ladder line. > Any recommendations for a homebrew blanched tuner. I hate to lay out a lot > of money for one since I think this may be my last adventure with using > ladder line, unless I can get one outside and up in the air. > > Alex - N4BYJ Hi , Alex, pse have a look at "The original Z-Match Design" http://www.njqrp/zmatch_original.html by Lofgren. A classic! 73! Dieter.DL2BQD ++++++++++++++++++++++++++++++ Date: Tue, 01 May 2001 03:23:02 -0500 From: Tom Hammond =?iso-8859-1?Q?N=D8SS?= Subject: Re: [Elecraft] balanced tuner It appears that the correct current URL is: http://www.njqrp.org/mbrproj/zmatch_original.html 73 - Tom Hammod N0SS ++++++++++++++++++++++++++++++++++++++ Date: Tue, 01 May 2001 09:03:58 -1000 From: John Buck Subject: Re: [Elecraft] balanced tuner A good choice for multiband usage of antennas while using an unbalanced tuner is the coax coil 1 to 1 choke balun. It is simple. 8 to 10 turns of coax about 8" in diameter wound on a plastic can to keep the turns neat. The input and output ends should be will isolated. A scramble wound bundle of coax does not work as well. This coil provides a high impedance isolation path for current on the outside of the coax. It cannot saturate like improperly terminated metal core baluns. I usually locate the coil in the attic or outside near the antenna feed point. I have used it to feed 450 ohm twin lead. With this approach the K2 autotuner tunes all bands and I am not troubled with rf in the shack. I have had some problems if the coil is placed right next to the radio but not if it is 10 feet or so away. I think that ferrite choke baluns, (Cores strung on the outside of the Coax), should work well also but since they sometimes get hot at higher power levels, they must not be as efficient as the air core balun. The experts will say that the choke does not yield a truly balanced output. True but I think you will not be able to measure the difference on the air. 73, John KH7T ++++++++++++++++++++++++++ Date: Tue, 01 May 2001 21:27:38 -0400 From: Brian Murphy Subject: [Elecraft] RE: balanced tuner Alex, Balanced tuners work great feeding ladder line to dipoles and loops with low system losses, especially for multi-band operation. I have used both the R. Measures Balanced tuner and the Johnson Matchbox balanced tuner. Both are described on the R.Measures website (try using www.google.com to search for the site). He has his article from QST from the '80s on building a balanced tuner. You should try it--it is easy to construct. The losses in the conventional "T" tuners when feeding ladder line typically occur in the high circulating currents in the balun at the output side of the "T" network which is best for only the balun's design impedances. Balanced tuners avoid much of these losses. Brian N4YTL +++++++++++++++++++++++++++++++++++ Date: Wed, 2 May 2001 08:53:04 -0400 From: Rick Robinson Subject: Re: [Elecraft] balanced tuner IMO the best solution to balanced tuners for QRO power levels are the 250W and 1KW EF Johnson Matchboxes, and the Harvey-Wells Bandmaster Z-Match. These older tuners are still available on auction sites and at hamfests. The original z-match tuner circuit appeared in a 1955 or so QST article and is the design that the Harvey-Wells uses. Using dual rotary inductors with motor drives, etc. is just too Rube Goldbergesque for me. There are much easier and less expensive ways to tune balanced antennas. For QRP, the Emtech ZM-2, the Norcal BLT and any other design by Charlie Lofgren, W6JJZ are best. Charlie has had z-match articles published in QRP Quarterly, Communications Quarterly, and the ARRL Antenna Compendium Vol. 3 and all are easily constructed with readily available components. I have a ZM-2, and a BLT and both work great with my K2. 72, Rick kf4ar ++++++++++++++++++++++++++++++++++++ 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 +++++++++++++++++++++++++++++++++++++ Date: Sun, 16 Dec 2001 15:45:34 -0700 From: "Ken Lotts" Subject: RE: [Elecraft] Balanced line ATU Neat.. Thanks for the comment.. I did a search on the ARRL site but no tally, so I guess I will need to get the book.. I did run into a very informative article (68 pages!) on SWR at: http://www.arrl.org/members-only/tis/info/pdf/Reflect.pdf I am still reading it.. seems quite good. Ken aa7jc - -----Original Message----- From: owner-elecraft at qth.net [mailto:owner-elecraft at qth.net]On Behalf Of Jerry T Dowell Sent: Sunday, December 16, 2001 11:35 AM To: elecraft at qth.net Subject: [Elecraft] Balanced line ATU Ken Lotts wrote: "This whole topic leads to an intersting idea that I have shared before regarding the fact that most (or possibly all?) commercial antenna tuners are built for unbalanced (coax) lines. It seems that baluns are questionably being placed in very ugly rf environments. I have found a great web site http://www.vcnet.com/measures/bbat.html that describes an incredibly easy way to make a balanced L tuner. The neat thing about L tuners is that they adopt easily into an ATU world. Think about it.. An ATU that is designed specifically for balanced line.. This would be a great product.. and as a bonus could even be designed to work in the unbalanced world with only a few switches (or relays)." Al Roehm's article "Some Additional Aspects of the Balun Problem", in the ARRL Antenna Compendium Vol. 2 (1989), page 172, makes it clear that a single L-network can be used to feed a balanced line with a proper balun on the input side of the tuner, simplifying automation. Thus two networks as Measures describes are not really necessary. The only switching required is for putting the capacitor on either side of the inductor, and, if desired, switches (relays) for selecting between antennas. Unbalanced antennas can be fed with the same network....it doesn't care! Al's article appeared in an earlier QST...I don't have the reference at hand. 73, Jerry AI6L ++++++++++++++++++++ Date: Mon, 02 Jun 2003 12:30:24 -0500 To: elecraft at mailman.qth.net From: Tom Hammond Subject: [Elecraft] BALANCED OUTPUT ATU, from PALSTAR Hi Folks: I just happened past this item and recalled several (past) correspondences with regard to true 'balanced output' ATUs. Thought this one might be of interest to some. It's rated at 1.5kW output and it's not exactly cheap, but it looks pretty nice. I wonder if anyone might have seen it in the flesh at Dayton this year? http://www.palstarinc.com/at1500BAL.htm 73, Tom Hammond N0SS +++++++++++++++++++