W8ji Trap Loss

DK3 „Screwdriver“ DK9SQ Antennen. pdf is worth reading. Total loss of two back-to-back transformers was. However, that's not the most efficient. The hand positioning of the trap bar helps reduce shoulder and elbow stress, making this a safer version of the standard shoulder press. 8 MHz, to close to 1. This would suggest that a 10m trap might be better. On that band the trap loss is 0. The primary purpose of antenna traps is to permit multiband operation. Instead of using an 80m trap, a relay ($2. In other words, the 5 watt QRP radio lugged to the top of the mountain will radiate around 1 watt with one radial attached to a quarter wave vertical. See W8JI's page for details:. trap panic in lv_resyncpv due to failure return from lv_lvhold call. The Balancer Unit weighs around 17 lbs and adds resistance to the motor. 73, Tom W8JI ***@contesting. ÿâ À› X @ðx5ðv ð ÿ œNè î 0qÞ+ ü— ‚s ê~ÿ )ÀÎ ?ŽY. 8 MHz, and eleminates the shunting effect of the trap for wanted signals. One thing to keep in mind, this design doesn't perform miracles with the false promise of amazing gain. the "no-trap is good" bandwagon to push their no-trap designs. In the right column, a parasitic reflector wire is added to the model. Balanced line has it's problems and many more than you experence with coax fed antennas. Search Search. 2014, I picked up a used 2012 defender 90 with 20,000km on it. The Reyco traps seem to survive reasonable power levels but not "big" amplifiers. 8dB loss per trap right at resonance 1. You will notice that the common mode choke balances the dipole leg currents very well, the feed line common mode current is greatly reduced, and the feed point impedance is correct. Orfanidis - Lots Of Math! MATLAB library of same. For 80 you could base load the thing, and a 43 foot vertical with a good ground would be decent. of inductor Q and trap impedance. Why is this equivalent correct?. "tuner"/"coupler"). html in zojumewucuh. Many years ago I moved into a house with a small garden of about 45 ft. by clap-trap appesla to the spirit of reverence We sorrow for his loss, and lean entitle him toour grati- j w8ji three, were, in spile of Lewis, the. Traps (W8JI) 4. I'm doing some rewiring of my shack and the antenna runs. The Library of Congress > Chronicling America > The evening times. Let's clarify a few points—perhaps we'll even debunk a few myths in the process: 1. We - including me - are using the term "trap" loosely. In the trap article by W8JI that I linked to above there are some indications but no hard figures on the performance impact. Check out our how-to articles to find out how to do things like embed videos, create a poll, quote a post, and more. Take a look at Tom's W8JI comments and real life testing on trap loss on his WEB site. That is often true. Let's say I have an 80/40m trap dipole which presents a reasonable match to 50 Ohms on both bands. trap antennas coaxial trap coax dipole antenna loss resistance. Excluding the coax trap articles, there are relatively few trap dipole projects written up or documented in places accessible via internet searches. ÿû d ði ¤ 4€ ÖåÊ(Ý-ÄF‚p ÿ Áë9 ì o)i£°. If you have a low-loss feedline, you can even do this with a tuner in the shack. At the lower frequency, where the trap acts as an inductor, the coaxial cable trap performs relatively better. The resonant. Navigating the passive activity loss rules can be a daunting task at times. c here to follow the link; if you want to rate Trap antennas, coaxial trap, coax dipole antenna loss Coaxial Traps for multiband antennas by dxzone. that's moderately consistent, although 2. The design. Baluns are devices to balance unbalanced systems. It is completely fac-tory pre-tuned and exhibits an extremely low angle DX radiation pattern. A single 50 ohm coaxial feedline is required. 004 db) is Lost in the Core with 1500 Watts Drive. > October 24, 1901 > Page 6, Image 6 Search America's historic newspaper pages from 1789-1925 or use the U. 33 Watts (0. , about ¼ wavelength. But the Force 12 is simply the best. Mit einer FD-4 und einem Trap-Dipol für 15 und 10 m hat man zunächst eine Arbeitsgrundlage für die Bänder von 80 bis 10 m geschaffen. PK hAO GLEASON_JibsBooms_BROCHURE. In a fixed station installation, reducing ground loss is simply a matter of putting. First, trap antennas are usually expensive. 5 acres of property and use a 2. To view a few of my antennas and station, look at MY STATION. This 5-band highly efficient no trap vertical antenna is located about 200 feet from the SVPA. You will notice that the common mode choke balances the dipole leg currents very well, the feed line common mode current is greatly reduced, and the feed point impedance is correct. 5 ohms explains both the wet and dry results. Radiation Resistance = Power radiated / input current squared The other portions are ground loss and antenna structure loss that dissipate power as heat. The only band on which the 6BTV has only a trap is 10 meters. Cebik - W4RNL. Photo C: The home-brew 12-meter trap Next we must resonate the traps where we want them to be. The hand positioning of the trap bar helps reduce shoulder and elbow stress, making this a safer version of the standard shoulder press. See Figure 1 and Photo C for the trap details. On this point I made an effort to follow W8JI’s information and make the traps resonant off of the desired operating frequencies to minimize trap losses. In the trap article by W8JI that I linked to above there are some indications but no hard figures on the performance impact. Last page update: 5 August 2017. Many years ago I moved into a house with a small garden of about 45 ft. See W8JI's page for details:. Stealth Antennas 20 12 Larry, W4SAT, says that in a test on a state-wide net, a 30ft 80m Slinky dipole at 20ft received signal reports on average 0. You will lose some band width and hopefully not too much efficiency loss, but it is better to have SOME antenna rather than NO antenna. [W8JI has created a web page which explores trap loss]. A tuned trap at the antenna terminals stopped it but otherwise the broadcast signal easily got through the front end of the SX-101 when operating on the lower two bands. I'm going to order some BuryFlex which will be used as the main runs to both of my antennas. Detuning a Tower from a Vertically-polarized Antenna In my previous article on a 2-element loop array for 40 meters I issued a caution regarding the potential harm from a tower that is resonant, or just near-resonant, on the band of interest. If you have a low-loss feedline, you can even do this with a tuner in the shack. Baluns - W8JI Antenna Articles Toroid Balun Winding * Balun and Transformer Core Selection * Transmitting Baluns Choosing Wire For An Antenna Coaxial Cable Trap Building-- BY Greg Ordy W8WWV. Calculates the attenuation, 'impedance', reflection coefficient, VSWR and return loss of a circuit that incorporates a RF tank circuit into a Pi attenuator. I added a jumper connecting three six foot (or so) ground rods to the common point of the radials, and measured a quite noticeable FS loss!. That's all. com Coaxial Traps for multiband antennas. 2014, I picked up a used 2012 defender 90 with 20,000km on it. I've found more on coaxial trap design including VE6YP's Coaxial Trap program. W8JI also has some interesting trap info published. "radiation" and "loss" resistances, but the efficiency is the same, and the formula works. Victor square pan # 1 1/2 coils # 21 Diamond single long, double jaw # 1 Herters single long. com) contents are listed below: TKO 600 transmission Shift Problems Amplifiers. W8JI, pleasesee here). Two New Multi-Band Trapped Dipoles (W8NX, SK) Useful Tools. Option 2) Do as you say and parallel-up the 80m and 160m quarter wave ants with a common 50 ohm feed point. Navigating the passive activity loss rules can be a daunting task at times. So there is loss, and it's well known that the loss goes up with miss match. I put a choke on the coax right next to the tv in but did not see much effect (no noticable loss either). Can a ground stake at the base of the feed point serve as a counterpoise, or does it need to be. The design. In tuning a trap there are two concerns which are somewhat contradictory: You want the trap to have a high impedance on the target band. com/profile/03628323460157887934 [email protected] W8JI also has some interesting trap info published. It reduces shunt capacitance rather than increasing it, but the result is a substantial (double) increase in the frequency of peak performance. W8WWV Antenna Experimentation. Cebik - W4RNL. On that band the trap loss is 0. Traps (W8JI) 4. 5-54 MHz and 2-2000 W. That was on the phased vertical array because the end fire NE direction is over the pole. The gain is -0. A combination of line loss (even with. A combination of line loss (even with. Mir ist schleierhaft, wieso sich so viele OM mit Trap- und Unun-Antennen, mit G5RV, W3DZZ, FD4 und Konsorten abplagen. Cebik - W4RNL. [W8JI has created a web page which explores trap loss] When this information becomes generally available, it might be time to reconsider the coaxial cable trap. Take a look at Tom's W8JI comments and real life testing on trap loss on his WEB site. The only number I could find for a voltage balun is a matched loss of 0. The 18AVT/WB-S is a multi-band trap vertical for 10 through 80 meters. If after reading these pages, you find you do not have enough space for a full size dipole, try one with traps, which reduce the length. Second, it reduces corona loss. October 26 2009 Baluns: Choosing the Correct Balun By Tom, W8JI General Info on Baluns Balun is an acronym for BALanced to UNbalanced, which describes certain circuit behavior in a. In the right column, a parasitic reflector wire is added to the model. Higher loss in coaxial traps occurs because a "capacitor" made from coax has low Q, an inductor made from coax has low Q, and the L/C ratio is poor. There are several options for this, the lower the loss the higher the price. Initial Trap Construction: The available values of capacitors also drove the selection of trap resonant frequencies. So for a 20m-40m dipole, resonant your trap at 14. A single 50 ohm coaxial feedline is required. Also, I felt that recent DX-peditions to VK9L did not address 160m demand. 300-Ω transmitting feedline is a better choice, since it moderates multi-band impedance extremes and still offers significantly less loss than coaxial cable in this application. Also build a multiband dipole for 80-, 40-, 17-, and 10-meters only 84 feet long. To my surprise, 11 students took the bait and signed up immediately. You could get a balun right there at the auto tuner input and hook >the feedline to it there. A couple of months ago, I ran across a design rated at 100 W. This is an empirical "shoot-out" between a 135' OCF dipole mounted up 40' in the clear vs. AMATEUR PHASING. com: 5/23/95 12:00 AM: Received: by ccmail from dlsun32. 8 dB at 30 MHz. End-Fed Half-Wave Antenna & Tuner - by VK2ZAY An End Fed Half Wave Antenna, by the late G3YCC end fed vertical j-pole and horizontal zepp - A reference of End Fed Myths - by W8JI (he'll dispel any believe that an antenna might work ;-) "EFHW" - the end-fed half wave antenna - by WA5BDU. A coaxial cable trap is a parallel resonant circuit that is usually inserted in an antenna element to enable. 300 OHM LADDER LINE. I've never been one to name my cars, but seems a few around here give them pet names as opposed to the usual 'The Land Rover' or 'The Holden/Ford/etc'. This provides greater attenuation at VHF/UHF frequencies where local high power TV and FM stations are located. End fed longwire or random wire antenna. 5 MHz for my resonant trap frequency. Slim Jim Antenna. I chose to use 1/2" heliax that was available as the run would be about 3. A single coax and control wire feeds into the shack. W8JI is an authority on all aspects of antenna design - including traps. 50 mhz: amateur radio direction finding: amiga: antenner etc. Balun Construction. I'm confused about the requirements for a counterpoise for an end-fed wire antenna. Check it out The Effects of Traps on Beams Experience has shown that the losses in gain of center loaded elements are additive, at least in 2-element. Perfect for building a dipole. Electronic antenna Сайт для тех, кто любит автомобили и не боится гаечных ключей. The primary purpose of antenna traps is to permit multiband operation. The file contains 14 page(s) and is free to view, download or print. I just worked him with an easy 59 each way. it contains measurements of traps, performance of trap antennas using models of traps, and ideas on how to make trap antennas more efficient. Limited Space Antennas - authorSTREAM Presentation. The article is an analysis of an antenna trap where a coil is formed of a length of coax cable, the outer conductor of one coax end is tied to the inner conductor of the other coax end, and the remaining connections (outer at one end and inner at the other) form the terminals for the trap. Ø•)u·NÝ9²3¼ ÿÿöP V 7ÿüç´(cÿ– Dƒ± ¡ × P Ÿ (H™?°¸ y Œã9ÏS “ûŸ´oS9äïÆh A0tâl¢ R “L " ³Éë“')˜†{&L"Ië§ÿû’d¾Ž i -–r'±ý b äÌ=Œz` yÌ@XZìðp½h’a {b ð C8 ™át/ À “}±`‘ Å”ï”×LÓ Ó$ÍlÙ ‡€ƒ Hć…SÆîsyc•ïKrý³†” 8àˆ CˆüSÔ Ðƒ. It's a rugged homebrew multi-band trap vertical antenna that works the and 20 meter amateur radio bands" Dipole and Inverted V Antenna Basics "This antenna project came out very nice. Excluding the coax trap articles, there are relatively few trap dipole projects written up or documented in places accessible via internet searches. Let's say I have an 80/40m trap dipole which presents a reasonable match to 50 Ohms on both bands. This power rating is for load impedances of ohms. Bootstrap coax traps for antennas. Trap Construction 25 Jan 2018 NSARC 12 Dual band dipole for 80 & 40 m The trap is a parallel resonant LC circuit that goes HI Z on the 40m band thus Isolating the wire ends which makes it act as a 40 m dipole On 80 m, the trap appears as an inductor in line with the antenna. that's moderately consistent, although 2. The feeder loss will be 0. In the above evaluation I used an ESR of 0. Can I feed it with ladder line and get rid of coax cable or should I build A new dipole for 160,75,40 meters and feed it with ladder line I have manual tuners and auto tuners too. I don't know whether anyone has mentioned it but electric field intensity around any charged object is inversely proportional to the radius of curvature of the object and since the air can stand only so much field intensity before breaking down it pays to keep the curves as large radius as practical. The 2:1 bandwidth is unaffected except by the additional loss of the tank circuit sitting across the dipole feed point. In the trap article by W8JI that I linked to above there are some indications but no hard figures on the performance impact. jpg, metadata. It is ironic that the antenna that mole pictured, is a perfect example of just about the worst antenna you could build compared to his testing. No traps, anywhere. So all the trouble of building a bazooka with both legs and the dipole. I have not tried this. Let's clarify a few points—perhaps we'll even debunk a few myths in the process: 1. You might want to put a fixed resistance only at the base to simulate ground system loss, then move the feedpoint up and down. 73, Tom W8JI ***@contesting. Parallel Resonance. However, the loss and hence quality factor of an inductor will to a certain extent be dependent on its form factor and conductor size. Für die untere Hälfte des Kurzwellenbereiches von 1,8 bis 14 MHz haben sich einige dänische OMs eine besondere Antennenkonstruktion einfallen lassen. Or approximately so. The objective of a trap is to reduce the currents on the inactive portion of the antenna to a negligible amount. You can tune the 32V into a 50 ohm resistive dummy load, and use the reciever and noise bridge to adjust the transmatch. The hand positioning of the trap bar helps reduce shoulder and elbow stress, making this a safer version of the standard shoulder press. First, trap antennas are usually expensive. A 20/15/10 Trap Dipole Barely Fits between the two TV masts Trap Dipoles • Traps are parallel resonant circuits - Below resonance, they look inductive - So they act as loading coils on lower bands • A 3-band trap dipole fits in less space than a fan dipole - 20/15/10 is about 26-27 ft (20M dipole = 33 ft) • Traps add some loss. Sogar 160m wird noch einigermassen gehen. com located at. 2x10 M (2x33 FT) MID-LOADED DIPOLE. Limited Space Antennas - authorSTREAM Presentation. Local HDTV Info and Reception - Adding 110Volt to Antenna location - Rabbit73, had a little more time today and did a test similar to the one you. Other than the TUNE OPERATE switch, there is no way to reduce power to safe levels on the 32V during adjustments. MARTIN - G8JNJ - Multiband HF Antennas - Martin - G8JNJ - ECLECTIC AETHER - Radio Related Ramblings. Building Coaxial Cable Traps by W8WWV See more. trap construction that my Google searches haven't revealed. Orfanidis - Lots Of Math! MATLAB library of same. Depending on which bands you want to operate, there is a better design which involves shortening the antenna and lengthening the section of ladder line. Feb 25, 2019- Explore harleyhero9241's board "Antenna" on Pinterest. So there is loss, and it's well known that the loss goes up with miss match. 3 Ω since, so far as I can tell, it is a value that is likely not to be too far from the truth. dBi is often what is used for gain specs on antennas, because it results in bigger claimed numbers. A combination of line loss (even with. A couple of months ago, I ran across a design rated at 100 W. 6 deg = 6 Ohms 5. Conclusion. Total loss of two back-to-back transformers was. by clap-trap appesla to the spirit of reverence We sorrow for his loss, and lean entitle him toour grati- j w8ji three, were, in spile of Lewis, the. I just Googled "Trap Loss W4RNL" to see what he had to say about this matter of interest to me. Electronic antenna Сайт для тех, кто любит автомобили и не боится гаечных ключей. Specifically the loss. You'll find that. Антенна Blaupunkt A-R G 01-E. Also build a multiband dipole for 80-, 40-, 17-, and 10-meters only 84 feet long. ground loss will be minimized. 32-34 You need this - traps with lower loss, higher Q, increased power-handling capability and four-band coverage. A simple tuner will match over something more than an octave (2 x frequency) so a 40m EFHW can be used on 20m. There are nuances that, if not addressed ahead of time, can have significant negative tax implications. A trap dipole antenna is a good choice if you only want to operate on two or three amateur radio bands and don't want to readjust an antenna transmatch (i. 218\scan14\root\projects\production ewspaper\LibraryOfCongress\The_Washington_Herald\TWH_19070709-19070912_0010049324A\ocr\0601. Mir ist schleierhaft, wieso sich so viele OM mit Trap- und Unun-Antennen, mit G5RV, W3DZZ, FD4 und Konsorten abplagen. Fan Dipole vs Trap Dipole (40 - 80) Where trap loss can be a problem is when somebody makes an antenna with a half-dozen or more traps of low Q. 40 meter coaxial trap eHam. Choke baluns are not quite as lossy, and can be helpful in maintaining a clean radiation pattern and keeping RF out of the shack. Trap Loss, or lack of it, in triband beam antennas, has always been a subject I have wondered about. I put up the longest wire that fit on my parent’s lot at the lofty height of 25’ and fed it with. Tribander Plus? Plus what? Friends with benefits maybe? Back in 2002 or so, references to the “open sleeve dipole” sparked a curiosity in the topic. AMATEUR PHASING. No traps, anywhere. First let me say I don't know much about Amps. An excellent summary of various coupling methods - and a short discussion of the shielded vs. Pros and Cons - alright, Cons! Rradiation is the loss due to the radiated fields. Overall, unless you put a tuner very close to the antenna, a trap vertical would work a whole lot better. com Coaxial Traps for multiband antennas. Excluding the coax trap articles, there are relatively few trap dipole projects written up or documented in places accessible via internet searches. QST June 2016 page 45 advocates the case for a dipole; the gist is the VERTICAL loop average height is lower than the identical dipole or inverted V and therefore low angle gain is lower and ground losses higher. WHY DO YOU GIVE A CRAP ABOUT ANY OF THESE THEORETICAL STATEMENTS?. Ask Question article from w8ji. RECENT ADDITIONS. I think you are neglecting the loss through the baluns and the miss match loss. The AS-2259 was designed to work with the PRC-47 in Vietnam. Now I have measured almost no loss from PL-259 connectors on HF I think the best way to reduce loss is to buy a good coax cable. 300-Ω transmitting feedline is a better choice, since it moderates multi-band impedance extremes and still offers significantly less loss than coaxial cable in this application. This power rating is for load impedances of ohms. [W8JI has created a web page which explores trap loss]. 50 mhz: amateur radio direction finding: amiga: antenner etc. This tends to be a resonable compromise between trap loss and ease of antenna adjustment. So there is loss, and it's well known that the loss goes up with miss match. Higher loss in coaxial traps occurs because a "capacitor" made from coax has low Q, an inductor made from coax has low Q, and the L/C ratio is poor. 075db, this would be times 2 in your setup. References. W8JI had this. pdf is worth reading. Some calculations demonstrate that properly designed and constructed traps would have insignificant losses (i. DX LISTENING DIGEST 11-07, February 16, 2011 Incorporating REVIEW OF INTERNATIONAL BROADCASTING edited by Glenn Hauser, http://www. October 26 2009 Baluns: Choosing the Correct Balun By Tom, W8JI General Info on Baluns Balun is an acronym for BALanced to UNbalanced, which describes certain circuit behavior in a. I've found more on coaxial trap design including VE6YP's Coaxial Trap program. Let's say I have an 80/40m trap dipole which presents a reasonable match to 50 Ohms on both bands. 8 to 30 MHz. Create a Member Swing Thread. Tom Rauch, W8JI Tom Rauch, W8JI, in his well-known high-Q inductor study once complained that many inductor modelling programs fail to consider two important effects: The stray capacitance across the inductor, The proximity effect, causing Q to decrease as turns are brought closer together. HyGain sells a Hytower, that while pricy works excellent from 80-10 and can be loaded to work 160. 150 MHz in this case. Because this antenna is designed for 160 meter reception (not transmit), I do not use resonant elements. antique radio, museum etc. Although it does not cover the specifics on the options I. The B&W folded dipole as a solution sticks in the craw of a lot of hams, because we always think there is some way to navigate the problems and keep the 3 dB for ourselves. You might want to put a fixed resistance only at the base to simulate ground system loss, then move the feedpoint up and down. One of the 20 mtr antennas that I built is a half-size 2-element "yagi" beam antenna, based on a design by Gary Hanson (KJ5VW), ref. February 7 of 2010 was a quiet Sunday. MARTIN - G8JNJ - Multiband HF Antennas - Martin - G8JNJ - ECLECTIC AETHER - Radio Related Ramblings. A good loop will be made of thick copper tubing and have solid connections. Introduction The DX Engineering DXE-SWA-148 Linear-Loaded Multi-Band Dipole (Patent Pending) is a 148 ft, lightweight yet rugged design that is usable with a tuner from 1. trap antennas coaxial trap coax dipole antenna loss resistance. I put up the longest wire that fit on my parent's lot at the lofty height of 25' and fed it with. Resources listed under Antenna Balun category belongs to Antennas main collection, and get reviewed and rated by amateur radio operators. A single 50 ohm coaxial feedline is required. INRAD model RX7300 - add a receive-only antenna jack to the Icom IC-7300. You will lose some band width and hopefully not too much efficiency loss, but it is better to have SOME antenna rather than NO antenna. Karel, OK1CF was one of my very first DX QSO’s back in 2001, when I got into DXing. Mir ist schleierhaft, wieso sich so viele OM mit Trap- und Unun-Antennen, mit G5RV, W3DZZ, FD4 und Konsorten abplagen. The loss in traps is greatly exaggerated. 4 million vehicles globally in which the automaker said the driver-side floor mat could trap the accelerator pedal. I have used TRAPS in a number of antennas over the years and never have been able to see any real loss in performance. By the way, while experimenting don't try this T/R switch with a solid state receiver unless it has a well protected front end. With the original four 125 foot radials, the antenna seemed rather quiet, and that should have been a sure sign it was too lossy. Diamond Antennas. 300 OHM LADDER LINE. com Items from DXLD. You want losses to be low. They are most lossy ONLY on the band they are trapping, and that loss is generally pretty small. This provides greater attenuation at VHF/UHF frequencies where local high power TV and FM stations are located. I understand that it's needed, but I don't understand what the requirements are. com Slide 2 A New Amateur Band After many years on the air using. With 500 segment capability, EZNEC can model very long and complex antennas, and EZNEC+ even more with its 2000 segments. Case study: 50 degrees 600 m long wire to Japan. One of the 20 mtr antennas that I built is a half-size 2-element "yagi" beam antenna, based on a design by Gary Hanson (KJ5VW), ref. There are bands where the G5RV has a high vswr on the line and with coax that results in high loss. During the following 15 years the amateur community contributed many innovations we use today like SSB, the yagi antenna, 2 meter moonbounce and SSTV over amateur radio bands, before half the country had a TV in their living room. Whereas a Dipole is a half-wavelength long radiator, fed in the Center of two equal length legs, the Off-Center-Fed Dipole (which I prefer to call a WINDOM) is a Dipole whose feedpoint is at a point removed from the center of the antenna. trap panic in lv_resyncpv due to failure return from lv_lvhold call. Bootstrap coax traps for antennas. The only number I could find for a voltage balun is a matched loss of 0. Before I get into the nitty-gritty details, let me first make a distinction between end-fed half-wave antennas, such as the ones sold by LNR Precision and end-fed wires that use some kind of tuning to achieve a 50 Ω. I have components for a trap dipole, but the bandwidth and loss eliminated them quickly during initial experimentation. I suspect that this loss might be as high as 3 to 6 dB. Information, reviews and projects relating to Amateur Radio and associated interests DC to Daylight. What others are saying This is the LDG and the DXV non-flag vertical dipole HF Radio Antenna for A LDG remote tuner and an all band, low loss, high-performance radio antenna that gets you on the air with DX Confidence. >Back in the July 92 issue of QST there was an article by Al Buxton, > W8NX, the described a space efficient 40/80/160 meter antenna. Well, as an update to my Carolina Windom project, I find that the CW OCF dipole cut to typical dimensions works well WITHOUT a balun but does not work at all WITH a balun. Choke baluns are not quite as lossy, and can be helpful in maintaining a clean radiation pattern and keeping RF out of the shack. The only thing that changes is the impedance the feedline "sees". Tim recommends 5K or more to add grid leak bias. required inductance. For minimum trap loss, W8JI (www. You might want to put a fixed resistance only at the base to simulate ground system loss, then move the feedpoint up and down. 8dB loss per trap right at resonance 1. html in zojumewucuh. Warning about antenna models! The dipole is the basic building block of many antennas. Newspaper Page Text THE UN WEDNESDAY JUNE 21 1000 14 4 JESUIT COLT COLLEGES GES UPHELD UPHELDItBV ItBV tin Dltu nEIL1I TO IRB IRBDBT PflEU PflEUt t DBT ELIOT or HARVARD HARVARDComparn JIAftVAflDL L Compares Jhlhodo MthodofTeurhIOiRfld of Trl1rhlnlad Coadma Coadmatbe Coudmnsthe the Electay Ierlln IjJltrraS1I Ifot lInard lInardAre 7 GradIAtS Are Not ot WrlEorted WrlEortedFlle WIIIdstated M. The 18AVT/WB-S is a multi-band trap vertical for 10 through 80 meters. impressed (the real reason must have been rather modest ground system, not the trap loss hi-hi). [W8JI has created a web page which explores trap loss]. 300 OHM LADDER LINE. W8JI wrote: ANY small area contact is a potential loss problemwelded, brazed, bolted, or soldered. An antenna tuner with a built in balun matches the feed-line impedance to the 50-Ω coax to your radio. Now I have measured almost no loss from PL-259 connectors on HF I think the best way to reduce loss is to buy a good coax cable. I have components for a trap dipole, but the bandwidth and loss eliminated them quickly during initial experimentation. Εντάξει τώρα, μην περιμένετε ότι ανακαλύψαμε τον τροχό! Όπως έχω γράψει και στο άρθρο με τις κυματοπαγίδες – trap, σε αυτή τη ζωή τίποτα δεν μπορεί να είναι τέλειο. The bandwidth will be very narrow; maybe 10 kHz on 80 metres. Vertical antenna ground plane keyword after analyzing the system lists the list of keywords related and the list of websites with related content, in addition you can see which keywords most interested customers on the this website.