+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Date: Sun, 8 Apr 2001 22:25:38 -0600 From: "Dick Knapp" Subject: [Elecraft] Fuchs (Fox) Ant I e-mailed Dieter, DL2BQD to ask him about the FOXX antenna and little film canister matching unit which he mentioned on April 5. He uses it for 40m remote antenna. Dieter kindly e-mailed me quite a bit of info on this ant. The ant is an end-fed wire of a full wavelength fed with coax and matched with a little coil (toroid) cap combo in a film canister at the coax termination. Dieter sent me an article in pdf format as well as a DOS program which calculates various combinations of caps and coils using various toroids. I knew some German once, so the article is quite interesting, but I don’t u/s most of it. I gather (maybe incorrectly) that the ant is useful for a given coil/cap combo for any number of half wave lengths of a given freq. There is a form of this ant called a Full-Grown-Inverted V which is raised in the middle a ¼ wavelength (I think that is what ¼ lamda is, right Dieter?) with the ends just above ground level – maybe 20cm. The radiation angle is very low, with results better than a 62m double zepp. Say, with my DK9SQ mast, this has possibilities! The matching system per Dieter for 40m: “For 7.02 he takes a T50-2 ring core, 30 windings 0.5 copper wire and a C of 120 pF. As a coupling he uses 4 windings on the "cold" end of the main winding. His wire length is 41,66 m”. There is a schematic in the article. The article and DOS program expand on the possibilities, if I could read them. The ant was developed by an Austrian named Fuchs (fox). It is used by some German QRPers (and others, I am sure). Dieter asked that I pass it on if it sounded interesting to me. It does. And Dieter, anyone who can build a K1 from English instructions has FB English skills, believe me! I can only hope that my understanding of radio theory someday is as thorough! Anyone interested in the article and the DOS program, please e-mail me (sorry, no web page) and I’ll get it to you. And I’d be interested in hearing about the theory of this ant from someone who knows – this is interesting. Ganz interessant. Dick Knapp KC7TUP K2# 315 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ Date: Mon, 09 Apr 2001 07:21:48 -0600 From: Larry East Subject: Re: [Elecraft] Fuchs (Foxx) Ant At 10:25 PM 4/8/01 -0600, Dick Knapp wrote: >I e-mailed Dieter, DL2BQD to ask him about the FOXX antenna and little film >canister matching unit which he mentioned on April 5. He uses it for 40m >remote antenna. Dieter kindly e-mailed me quite a bit of info on this ant. >The ant is an end-fed wire of a full wavelength fed with coax and matched >with a little coil (toroid) cap combo in a film canister at the coax >termination. Dieter sent me an article in pdf format as well as a DOS >program which calculates various combinations of caps and coils using >various toroids. I knew some German once, so the article is quite >interesting, but I don't u/s most of it. I gather (maybe incorrectly) that >the ant is useful for a given coil/cap combo for any number of half wave >lengths of a given freq. Boy, I really got worried when I saw "Fox(x)" in the title -- thought maybe Fox(x) Hunts were invading this list as well! :-) (I added an additional "x" in order to bypass all the email filters set to trash messages with that "F-o-x-word" in the title! :-) Such a tuner appeared in the QRP Quarterly several years ago -- can't find the article at the moment -- and also in the web mag, "ARS Sojourner". I used a similar thing -- but not in a film can -- many years ago with a 1/2 wavelength vertical on 40M. The idea is as follows: An end-fed antenna that is 1/2 (or one) wavelength long exhibits a very high impedance. A parallel tuned circuit (at the operating frequency) from the end of the antenna to ground with a link coupled input will give a pretty good match to a 50 Ohm rig. Even better is to connect the rig to a tap near the low end of the tank coil, adjust the tap position until a 1:1 match is achieved and also adjust the capacitance across the coil to maintain resonance. As an end-fed antenna becomes longer than one wavelength (but still a multiple of 1/2 wave), its impedance begins to drop. Such a matching network will still work if the antenna is also connected to a tap on the coil rather than to the "hot" end. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Date: Mon, 9 Apr 2001 08:42:22 -0700 From: alta Subject: Re: [Elecraft] Fuchs (Fox) Ant Couldn't resist replying to a thread with a subject-line like this... Dick, please send me a copy of the article. I may put it on the web to make it easier for others to see. I use air-core coils on my Zepp (for high Q), but would be most interested in the German torroid design. I use an end-fed Zepp like the one descrbed, both at home and when backpacking. I believe it has the most favorable effectiveness/weight ratio of any HF antenna. Europeans and Japanese operate it without a counterpoise. Americans seem to believe it won't work without a counterpoise. Mine seems to work great without a counterpoise, even in America. Now that I have the K1 antenna tuner, I use the same matching module and wire for both 40m and 20m. The matching module is a capacitor inside a pill container that has a coil wound around it. The module connects directly to the end of the antenna. The 1/2 wave Zepp is designed for 40m, having a native 1:1 SWR at 40m. At 20m it is full wave, and the 40m matching unit will not natively provide 1:1 at 20m, of course. Either way (40 or 20), the end impedence of the wire is very high -- probably 2000-5000 ohms. The K1's antenna tuner *easily* matches to the lower impedance matching module. Normally, I avoid discussing Zepp antennas on lists like this because I get too many messages from people who have never used one, saying that it won't work well without a counterpoise, etc. However, I am happy to discuss the details with anyone who is willing to do real work with a Zepp. 72 ... Reed K7FLY ++++++++++++++++++++++++++++++++++++++++++++++++ Date: Mon, 9 Apr 2001 14:53:19 -0700 From: alta Subject: Re: [Elecraft] Fuchs (Fox) Ant Doc ... You will hear all kinds of theories about the end-fed situation, and here's my two cents worth... I have experimented with the parallel-line fed end-feed. It is a transformer, and therefore it must have an electrical length of 1/4 wave, otherwise you will have mismatch and significant transmission line radiation. I do not like the bulk of the feed line or the required length of this scheme for portable situations. "My" approach, I discovered years ago from the Japanese. In the truest sense of the word "Zepp," it may not be a Zepp. It is a coil and capacitor netowrk at the end of the 1/2 wave wire that transforms the impedance from 50 ohms up to 2000-5000 ohms, whatever. So, the feed line is coax, and its length does not matter much (in my opinion and experience). When backpacking, I use a 5-foot length and it loads up fine for me. I have also used this from an airplane with a 5-foot coax. At home, the matching module is driven with much more coax. This latter scheme might be the same as the German scheme that initiated this thread. I'm sure a counterpoise wouldn't hurt, could probably help, especially if needed for peace of mind. I am curious to see what the German article says about counterpoises and grounds. I really don't want to bogg down the reflector with arguments about all this, but I will read the comments with interest. Here follows the construction details. ... Reed K7FLY - -------------------------------------------------------------- The 40m QRP rig feeds output over a 4-5 foot coax (or any length) to the matcher. The matcher connects to a 67' wire (half wave). The matcher is a 1.25" diameter by 3" long plastic pill container (available in your medicine cabinet) with BNC on one end and binding post on the other. No box; very light. The hot lead from the coax goes to a 50 pf transmitting capacitor (6 KV, in mine). Use the correct kind of cap. The other side of the capacitor is connected to the coil and the high-impedance output of the matcher. The other side of the coil is connected to ground. The capacitor is inside the pill container, and the coil is wrapped around the outside. The coil is 24 turns of #16 or #18 enamel wire. It is close-wound, but the coils can, and will, be spread for fine-tuning. Here are some benefits that make it useful for backpacking: - - Very light. Less wire -- only a small amount of coax required. - - As effective as a dipole. - - No ground required. (Some folks will argue this point.) In my experience, this is far more effective and reliable than the long-wire and counterpoise scheme that is popular with US backpackers. For 40m, no other matcher is required in the antenna circuit. The above-described hardware also works fine for 20m (also without ground) if there is a conventional antenna matcher added between rig and Zepp matcher. ++++++++++++++++++++++++++++++++++++++++++++++++++++++ Date: Tue, 10 Apr 2001 08:37:53 -0600 From: Larry East Subject: [Elecraft] Film Can Tuner The article on a "Film Can Tuner" that I mentioned in a previous post can be viewed at http://www.natworld.com/ars/pages/back_issues/2000_text/0100_text/film.html Check it out -- it's in English! :-) 72, Larry W1HUE/7 +++++++++++++++++++++++++++++++++++++++++++++++ Date: Fri, 11 May 2001 07:36:20 EDT From: BlackLabPupp@aol.com Subject: [Elecraft] RE:Wire antenna question "b/ a 50 meter "long"wire in a flattend sort of open diamond, the inv. v from above with the lower legs bent back towards the house. With a bit of creative garding there'll be room for the counterpoises." Leo one thing I discovered in building antenna's, is I will never use a long wire again unless it is the only choice. If you dont have a good and I mean 'good' ground you will end up with alot of rf in the shack. Here in Florida where I live you can dig about six inches in the earth and you come into gray sand and then shortly it turns with. Sand is not a ground. They make glass from sand. After putting in several 20 foot lengths of cold water pipe I still didnt accomplish the ground I needed. The solution was to remove the long wire and call the electric company and have them place over 100 feet of pipe to achive a ground. Now my home is the lightening rod of the neighborhood. A trade off I guess. After putting up another long wire just to test the performance, my conclusion was that I was better off with the loop. My favorite is a delta loop built standing vertical. I could say more on the subject but my advice is that there are much better antennas for DX than a long wire but if you are not looking for DX I dont think the long wire is no better than any other antenna. 73's Gene ++++++++++++++++++++++++++++++++++++++++++++++ Date: Sat, 12 May 2001 08:47:46 +0100 From: "David Johnson" Subject: [Elecraft] Wire antenna question >Date: Fri, 11 May 2001 12:04:52 +0200 >From: "Leo Starrenburg PE1OBG" >Subject: [Elecraft] Wire antenna question. >hi all, >i'm about to put a wire antenna over the house. There just about space >for: I've used a doublet with a 100 foot top section in inverted V for years There is approximately 20 foot of open wire "ladder" line from the centre to a home wound 4:1 balun on the outside wall of the bedroom shack, 10mm hole drilled straight through the wall and 3 feet of RG-58 coax to a commercial ATU (Vectronics VC300DLP). It tunes all bands from 80 to 10 metres. Results on 80 to 20 are very good, although the ATU tuning is quite critical on 80. Above 20 metres the efficiency tends to drop off, although I did work the VP8SDX DXpedition recently on 17m (with the K2). There is virtually no electrical interference picked up by the antenna and little computer noise from the shack computer. The wire I use is 32/0.02 (1mm area). The balun is mounted in a plastic box with brass nuts and bolts to bring the connections to the outside for the ladder line. A very cheap and effective antenna, I wouldn't bother trying an end fed antenna as the doublet is so easy to make and works so well. 73's Dave, G4AON K2 #1892 KSB2 KBT2 +++++++++++++++++++++++++++++++++ Date: Thu, 31 May 2001 06:50:21 -0700 (PDT) From: Jeff Burns Subject: Re: [Elecraft] rubber ducky Date: Wed, 30 May 2001 21:35:53 -0400 From: Subject: Re: [Elecraft] rubber ducky ---snip------- "But permit me apply this perspective to a long wire antenna. I could probably get away with a full half wavelength #30 or thinner wire dropped straight down with a fishing sinker at the end (that is, when the wind does not blow). I know that such an end fed long wire should be over a quarter wavelength from the steel building it parallels, but that seems impractical at 20 meters or below. How do I calculate the loss resulting from a passive element (the building) located less than a quarter wavelength from the fishline driven element?" You can try a resonant sleeve dipole. Hang a section of coax off the balcony that is half the length of a dipole. At the far end attach a wire to the center conductor that is the length of the other half of the dipole. At the point were the coax should stop acting as half of a dipole and start acting as a feed line make a small coil of the coax. You can use a pole to hold the antenna out form the building. Jeff Burns AD9T ++++++++++++++++++++++++++++++++++ Date: Thu, 19 Jul 2001 14:09:29 -0500 From: "Stuart Rohre" Subject: [Elecraft] Stealth long wires, and more successful radiation antennas Hi, This is a common problem, someone needing to operate with little attention to themselves, and low visibility antennas. First of all some mechanics: No. 26 enamel wire is going to be pretty flimsy, and will easily be broken in friction of limbs blowing in the wind. You may want to live with having to splice pieces back together every few days, if in a windy area, but there are MUCH BETTER solutions both mechanically and electrically. You could go with a slightly heavier gauge, such as 24, and for low observability, spray paint the wire with flat black paint. Once high enough in the air, it will fade into the sky background, and the only thing you will see is a bird perching in mid-air! I have a local friend who does this with his low band dipole. Now as to length, and height. You need to have it up high enough that folks will not see it, but also, if you make a wire a wavelength or better, at a frequency, it is too directional to the far end of the wire, limiting your contacts to one direction. The longer the wire is, the more directional it becomes, and you likely would like more than one direction, unless you are on the tip of FL and can direct the wire NW or N! Bending the wire might help, but can cancel radiation, as I found out with a quarter wave on 40m. In general, I have had single wires from quarter wave on 15m and 40m to 400 feet long, and none of them worked worth a flip! The key was in not having an adequate counterpoise. You can use the 40m counterpoise on 15m, but you MUST have full length for 40m to work well. It needs to be run as straight as you can, but around the base boards of the apartment if no other way is possible. Better to also have it outside, running along the side of the building. Again, you may need to paint it a stealth color. However, my preferred stealth antennas are dipoles, using buttons as insulators. Or even synthetic fishing line. Run the center back to the eaves of the apartment or under the balcony where you can use TV twin lead to feed it. Anyone seeing twin lead will think TV, and not give it further thought. Even better, is to run around under the eaves with a loop making it a wavelength at 40m if you can. Circle the building if at all possible to install. If not, you will be using a tuner anyway for other bands, so it will do what it can to make it useable. Even run one side under the edge of the roof, or in a plastic gutter, and three sides out to the woods. You can support the wire, (if no plastic gutter), either on TV standoffs, or Electric fence insulator standoffs hung under the eaves. Screw in TV insulators are available at Radio Shack nation wide. Again use small wire, such as 24, and paint it to match the eaves color. The center of the dipole is low impedance thus can be brought close to the balcony, or a window for feeding without much loss. The window can have a thin board inserted at the bottom or even a piece of flexible pipe foam insulation. Poke a hole thru it for the twin lead, and simply close the window sash collapsing the tubing to a flat oval and you are in business. Cross the window sill at right angles, and there will not be losses even if it is metal sash. Another idea is to operate from a balcony if there is one, using headphones to avoid neighbor notice. When done, disconnect the feedline, and take it inside, and no one is the wise with the thin wire. If you operate with a 15m twin lead or ladder line fed dipole and tuner, you can make it work on 20m and 10m. Giving up 40m in the summer is no big loss, what with summer thunderstorms. Again, if possible avoid just running a wire straight out from the shack/rig, as that will limit your possible contacts to mainly one direction. Been there, done that, both as a US station and as a DX station with the 400 foot long wire. GL, and a low loop gave me over 6500 points in this last field day, it was only 20 feet high, about eave height on average building here. Of course, it was 849 feet around! But that is another story. 72, Stuart K5KVH To spray paint small wire, make a half circle from a piece of cardboard to confine the overspray, and make the spray reach all sides of the wire. Slide it along behind the wire as you spray, and you can paint a length, let it dry, roll it up, and unroll the next section to be painted, until all is done. +++++++++++++++++++++++++++++ Date: Sat, 29 Sep 2001 13:03:50 -0500 From: Dave Gingrich Subject: Re: [Elecraft] QRP G5RV? At 11:04 9/29/2001 -0400, penzo@juno.com wrote: >Sure seems like the K1/K2 automatic antenna tuners would work well with a >G5RV. Has anyone had any luck using a G5RV at QRP power levels? Better >yet, does anyone know of a QRP version of the G5RV (light weight - >compact like the gusher dipoles)? It should work fine but why go to the trouble of building a G5RV? The KAT2 is completely capable of matching virtually any length of wire. For portable operation with my K2/KAT2 I carry two lengths of wire: An 85 foot long radiator that I get as high as possible, and a roughly 60 ft piece that I use as a counterpoise. Both pieces are plugged into the KAT2 with banana plugs. Matches perfectly on all bands, and I continue to be stunned by how well it works. I specifically chose 85 feet because that length is not resonant on any Ham band, thus avoiding any high voltages that might occur on odd half-wave intervals (although not likely to be a problem at 10 watts). The length of the counterpoise is not critical, so I used 60 ft so I would have 150 feet left from the 300 ft of the expensive Flexweave wire I bought (about $.15/foot). A resonant antenna is perhaps easier to match, but resonance (or lack thereof) has virtually no effect on efficiency if you can couple power into the complex impedance, especially if the transmission line length is zero. The KAT2 does that very nicely. K9DC K2 #2211 ++++++++++++++++++++++++++ Date: Mon, 8 Oct 2001 15:59:25 -0500 (EST) From: To: Don Cc: Low Power Amateur Radio Discussion Subject: [108308] Re: Antenna ?? Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII On Mon, 8 Oct 2001, Don wrote: > Hello Dennis and Karl, > Sad but true, we don't all have room for a 120 foot > doublet. I'm surprised it hasn't drifted through the list, but a couple of excellent guides for various wire antennas such as end-fed inverted L, loops, etc., are available at http://www.sgcworld.com/. First is the manual for the SGC-230 auto-tuner and the second is a document covering stealth antennas. Both are excellent reading, even if you don't have an SGC tuner. Among the advice for the end fed wire was to pick a length that avoids resonance on any band. Tuners can have difficulty if the impedance to match is extremely high which happens at odd half-wavelength intervals. They suggest 85 feet, or if you have more room, 150 ft. FWIW- Dave K9DC ++++++++++++++++++ Reply-To: From: "Ron D' Eau Claire" To: Subject: RE: [Elecraft] Antenna Question Date: Sun, 24 Mar 2002 10:35:36 -0800 >...I'm thinking of a 67ft wire from the roof > to a tree, > end feed with about 30ft ladder line comming into the upper floor "shack". > The ARL handbook indicates a transmatch is needed. ...Any thoughts or > recommendations will be appreciated. >> john > va3jsl@rac.ca That's sort of a Zepp antenna. They are VERY frequency-sensitive if you want to avoid a lot of radiation from the feeders. The original Zepp used a 1/2 wave radiator and a 1/4 wave long feeder. You provide balanced feed to the open wire line at the rig. At the other end ONE side of the feeder goes to the radiator and the other side is insulated and connected to nothing at all. The 1/2 wave radiator shows a high impedance at the end where it is fed, so very little current is drawn from the feeder. It is a classic "voltage" feed with very high r-f voltages at that point. Since the current in the side of the feeder going to the antenna is very low, and the current on the side of the feeder that connects to nothing is also very low (only whatever leakage there is through the insulator), the currents in the feeders will be fairly well balanced, preventing radiation from the feeder. The 1/4 wave long feeder transforms that very high impedance into a low impedance at the ATU in the shack, which keeps the r-f voltages there low. The moment you move from the frequency where the radiator is exactly 1/2 wave long it will start to 'draw current' from the feeder. Since only one side of the feeder is connected to anything, that will unbalance the currents in the feedline and it will begin to radiate. Still, it can be an effective antenna, although at any but the design frequency it is more like a simple 'end fed' wire with the antenna coming right down into the shack. Also, on some frequencies you will develop very high r-f voltages at the ATU end of the feeder. One time I literally burned up a 300 watt balun (and melted a nylon binding post) running only 10 watts! I was using an end fed Zepp on various bands and hit a combination that put the voltage loop (high impedance point) at the ATU. Even at 10 watts there was plenty of r-f voltage to arc between windings on the balun and melt the insulation on the binding post. You might do as well or better by simply end-feeding the wire since you are already on an upper floor. The KAT2 should handle that just fine. If it has trouble on one band, just change the antenna length a couple of feet and you should be able to find a length that it can handle on all bands. You will want to use a tuned counterpoise - a 1/4 wave long wire for each band - one end connected to the K2 case and the other end insulated. They can be run anywhere as long as they are insulated. On bands where you have a high impedance at the rig they will keep the K2 at r-f ground and avoid problems with 'r-f in the shack'. On bands where the antenna presents a low impedance at the rig, the counterpoise is essential to provide an efficient r-f ground. Without it, most of your power will be lost in the poor 'ground' connection instead of being radiated. Be careful though, the far end of the counterpoise can cause r-f burns if someone touches it. An alternative to separate counterpoise wires is to use an "Artificial Ground" like MFJ sells. It's a simple L-match and r-f ammeter that you use to tune a single counterpoise wire to 1/4 wavelength at the operating frequency. That provides a good 'r-f ground' at the rig end. I have used one with very good results. I have used one successfully with a counterpoise wire that was as little as 1/16 of a wavelength long on the operating frequency (16 feet on 80 meters) although I believe that Moxon suggests about 1/8 wave as a suitable 'minimum' counterpoise length. If you are where must have a fairly long run before your antenna is out of the shack and 'in the clear', you might want to consider a balanced antenna instead - a doublet fed with the open wire line in the center. With balance feed you will avoid radiation on the feeders as long as the two halves of the antenna are the same length and fed from a well-balanced source. It will work well on any frequency down to where the 'flat top' is 1/8 wavelength long. One of my favorite books for all manner of interesting and effective wire antennas and tuner designs is a little book by John D. Heys, G3BDQ, called "Practical Wire Antennas - Effective HF Designs for the Radio Amateur". Published by the Radio Society of Great Britain (ISBN 0 900612 87 8) it is available from several sources, including the ARRL here in the USA. Ron AC7AC K2 # 1289 ++++++++++++++++++ Date: Sun, 24 Mar 2002 20:54:30 EST From: ARDUJENSKI@aol.com To: qrp-l@lehigh.edu Subject: [123106] Say you want to know about end fed wire antennas? Want to know about end fed wire antennas? Take a peek at what this site offers: http://www.qsl.net/wd8rif/archives.htm#antennas Also you may want to atake a gander at: http://www.njqrp.org/n2cxantennas/halfer/ http://www.qsl.net/aa5tb/efha.html http://www.g3ycc.karoo.net/ants.htm http://www.g3ycc.karoo.net/w3edp.htm http://www.easystreet.com/~w7zoi/endfeed.html http://www.natworld.com/ars/pages/back_issues/2000_text/0600_text/dk_vert.html http://www.g3vgr.co.uk/hw_ant.htm http://www.qsl.net/wb3gck/tuner.htm these are a sample of what you can find on www.google.com. Alan KB7MBI in Woodinville, WA FISTS 5702 Proud member of ARRL +++++++++++++++++ Date: Wed, 25 Sep 2002 08:50:59 -0700 (PDT) From: Lloyd Lachow Subject: Re: [Elecraft] K1 End-Fed Wire Antenna Recommendations To: Janet Beckett , elecraft@mailman.qth.net --- Janet Beckett wrote: > Just finished #1265 and wanted some recommendations > on the best way to > hook up an end-fed wire antenna directly to the BNC > connector. Any > suggestions? Janet, I get fabulous results with a ~200' wire up about 25' (actually, it has about a 15' vertical section on either end, and some twists and turns), and four counterpoises. I have a BNC-to-binding posts adapter, with the longwire in the red side (but only while I'm operating), and the counterpoises on the black. My K1 has 15-20-30-40, so my counterpoises are: two at about 16.5-17', and two at 33'. They're just run out along the basebopards on the floor. ===== 73, Lloyd, K3ESE K1 # 00379 - ARRL ARS #1301 - FISTS #8774 FPqrp #476 - QRParci #11147 QRP-L #2415 - SOC #530 HGT #6'1 - Wgt #190 - BT #B- ++++++++++++++++++ Reply-To: From: "Ron D'Eau Claire" To: Subject: RE: [Elecraft] K1 End-Fed Wire Antenna Recommendations Date: Wed, 25 Sep 2002 09:01:27 -0700 There are several fancy adapters that you can buy, but my recommendation is to get a BNC to SO-239 female adapter and a banana plug. Both are available from Radio Shack. The adapter equips you to hook a "large" coaxial connector to your K1 any time you might need to do that. The banana plug fits snugly into the center hole of a "large" coax connector (the type commonly used for RG-8, etc.) to provide a secure and simple way to connect an end-fed wire to it. The banana plug has the advantage that should someone every trip, fall, grab or otherwise YANK on the antenna wire, the banana plug will pull free of the connector without launching your K1 off into the blue somewhere on the end of the flailing antenna wire. Ron AC7AC K2 # 1289 +++++++++++++++++ From: "Sandy, W5TVW" To: "Janet Beckett" , Subject: Re: [Elecraft] K1 End-Fed Wire Antenna Recommendations Date: Wed, 25 Sep 2002 14:19:04 -0500 Go to a reputable radio supply house and get a Pomona BNC to binding posts adapter. Radio shack sells one, but the quality is "so-so" as it's made in China or Taiwan. I bought a couple of those and was very disappointed with them. They don't compare quality wise with the Pomona ones! Don't forget you need some sort of a "counterpoise" or at least one radial hooked to the ground post of the adapter! This is assuming you have the KAT1 tuner card installed? 73, Sandy W5TVW ++++++++++++++++++ To: elecraft@mailman.qth.net Subject: Re: [Elecraft] Random Wire??? From: "Steve Lawrence" Date: Thu, 9 Jan 2003 10:22:21 -0500 In Alan Chester's (G3CCB) (SK) article "Taming the End-Fed Antenna" (page 118 of the "Antenna File" published by RSGB) Mr. Chester rationalized that there might be some impedance friendly length of wire usable for an end-fed antenna that doesn't present a tough to tune, high impedance load on several bands. The "undesirable" length being on/near 1/2 wavelength or multiple thereof on the desired operating frequency. He concludes a length of 1/8 - 3/8 or 5/8 - 7/8 wavelength (or multiples thereof) represents the desirable targets to reduce impedance and therefore improves the ease of devising a suitable match. Mr. Chester proceeds to plot the length of wire, staying way from the 3/8 - 5/8 wavelengths (or multiples thereof) for the bands from 160M - 10M. The resulting plot is examined for lengths that fall in the "desirable" range for as many bands possible. >From these plots, he looks at several end-fed wire lengths: 26.5m, 15.0m, and 10.0m. Conclusion? The 26.5m wire appears suitable for 160 - 10M; the 15.0m length for 80, 40, 20, 17, 15, 12, and 10M; and the 10.0m length for 80, 40, 30, 17, 15, 12, and 10M. While I don't (yet) have experience with these results, the rationalization appears sound. I'm planning to conduct some experiments this spring! Steve AA8AF +++++++++++++++++