49:1 unun wire lengths
Designed for use with single wire unbalanced antennas, this new addition is small, compact and perfect for quick portable/emergency installations. Usually any wire length that is non resonant, like those shown above, will work with the 4:1 ratio. A way of connecting the analyzer to the transformer. Drill out holes in the designated bottom of the electrical junction box for the SO239 chassis mount. Legal Stuff a more capable tuner - see AA5TB's The vertical (y-) axis shows the VSWR and the horizontal (x-) axis shows the frequencies. Just an FYI that I thought you might be interested in. Just a note, if you make one of these yourself, you need to twist together the first two wraps of the 14 winding wire with both wraps of the two winding wire. gnuplot When you're antenna (or radial) length's an odd multiple of the operating freq, you may not need a balun or even a transmatch. For those that enjoy the LNR and Hy Endfed antennas, but want to run more power, Balun Designs now offers an excellent alternative. Wait a few minutes for glue to set. The 49:1, shown in my previous message, is meant for the EFHW that are fed close to or on the half wave (highest impedance) point. 3 0 obj /Type /Page So those are the numbers above thatwe have to stay as far away from as possible when building a long-wire antenna. The bandwidth where SWR was below 2:1 was about one MHz. As an example, a 28-31 foot wire will typically allow 40 thru 10 meter coverage and a 43-50 foot wire will provide access to 80 thru 10 meters. I have included a screenshot showing the stations that reported spotting my 200 mw beacon over the last 16 hours. 2 0 obj /XObject << /Im0 9 0 R >> Thank you so much for such a great product! That's it in a nutshell..or is it? 1 0 obj are easily converted to half wavelengths by the famous 468/f generally I swept the VSWR of the unun and resistors as described from <1 to 55MHz. endobj Gil Gruson 1 Campaign | Comines, France $0 USD 0 backers 0% of $3,450 Flexible Goal Follow Story FAQ Updates 0 Comments 0 Prototype The project team has a working demo, not the final product. Random wire lengths you should and should not use! He had heard good things about 'Balun Designs' so he recommended you. We hoisted the free end of the antenna wire approximately 30 feet into a tree. Caution: When used atfull power rating of 1kW, the antenna must have a low SWRon the band selected and be used on a 50% duty cycle. /Length 6 0 R <> 4 0 obj high the other 1.5m (4.5feet). You have to give up a band or two, like 60m and 6m, as Hi guys,not really hfu related,but I tought I might ask here as I have my account. You can get good loading and low swr on sometimes 2 or 3 bands, but one or more of the bands thatyou want, just will not cooperate with an swr that can be adjusted with the "tuner". For example, An Unun is used to match an unbalanced line to another unbalanced line. used by hams for dipole lengths. The second smallest number I measured was 2.7pF, derived from the self resonance at 2.72 MHz with the magnetizing inductance (measured at 25.8 H) with the secondary open and the output wire folded to a small 1/2 length. In stock . I got three FT240-43 toroids (two would be lighter, but three increases the curie point so it can handle longer duty cycles), a spool of the 14 gauge enameled wire . << That is the 10th multiple of a half wave on 15 meters. these are the worst lengths and you want to be as far from colored Built with the same craftsmanship as all our other For those that enjoy endfed antennas but want to run more power, Balun Designs now offers an excellent alternative. Cannon". See the picture below. Some of these numbers are too close to squeeze in between them. stream //-->, The "Best" Random Wire Antenna Lengths Y &lD30. I say run what you got and don't worry about it. We'd really appreciate it! This is considered a random wire end fed antenna, not to be confused with a half wave end fed antenna which uses a 49:1 or 64:1 unun and a wire that is a half wave length. It is important to use a counterpoise. (Center fed is so appealing because you avoid this.). PVC Junction Box(Home Depot), 1 x 1/2 in. When used with the stated lengths shown in thetable below, the 9:1 ratio will Based on the success of our model 4932, this 5kWconfigurationisalso perfect for matching both long and short length wire antennas for multiband use. This is a followup video to #344 where I assembled the 49:1 UNUN kit from HF-Kits / ARRL. BUILD INSTRUCTIONS FOR 49:1 UNUN IMPEDEDENCE TRANSFORMER: WX1MAR and I brought the DIY 49:1 unun with a borrowed antenna radiator wire cut for 20M half-wavelength to Ashland State Park K-2417 in Massachusetts for a Parks-on-the-Air (POTA) activation. . My homemade 49:1 EFWH with a 60 wire (cut for 40M) would do just fine! Two pieces of 14 gauge enameled wire (e.g., Thermalese), one short piece (about 1 foot in length) and one long piece (about 7 feet in length). I connected the free twisted end of the short and long wires (the ground) the chassis wire (ground) of my homemade testing jig with alligator clip. You are using an out of date browser. We do not encourage any radio operations contrary to regulations. /Subtype /Image want the antenna to be at least 1/4 wavelength long for each band you Use a slide rule! >> Enclosure Depth: 1.250 in. NOTE: Rewording the previous paragraph, if you have a capable enough rig, often with no feedline, and the other end in the air attached to So you have the freq range of interest and the total length of the wire, figuring out wich balun will be a better match for 50ohm coax should be easy. %PDF-1.7 To summarise the results WRT to reference antenna consisting of 30ft wire vertical fed with auto- is that for a given ham band there are min and max frequencies which Site Map shown in the column e. var sc_project=8077274; Quantity: Sold individually. Several ways exist to bring the wire's high impedance feedpoint closer to the desired 50 ohms, including use of a 49:1 or 64:1 unun, which eliminates the need . You will also need a half-wavelength length of wire (14 or 12 gauge typically) in order to construct an antenna radiator for whichever ham band you choose. The 30 day return period lapsed before I could get the antenna deployed to test it. uR5I5z G^u2`j[}+sy9 That type of wire antenna could be lower than 50 ohms at some frequencies and over 2,000 ohms at . random wire should use 423/f. ", KiwiSDR Online Radio - 500 ft Northeast Beverage, KiwiSDR Online Radio - 400 ft South Beverage, KiwiSDR Online Radio - 10/11m dipole up 20 meters high. The following is a list of materials required to make a 49:1 unun impedance transformer for an end-fed half wave antenna. Anyway, an old friend mentioned 'MyAntenna.com' but they were closed for the summer. well, the main antenna wire goes to the 9:1 UnUn "+" connector, the vertical counterpoise (insulated !) Here they are in order: this He used 300 ohm twin-lead and a 4:1 UNUN, with a 1:1 current choke between the UNUN and the coax to the tuner and transceiver: The full-size "flimsy" (ref. Best SWR was . Product Reviews tuner the colored bands below are the best lengths as long as your Custom mix low permeability ferrite by Fair Rite Products for maximum bandwidth. >> I purchased a MFJ-16010 Random Wire Tuner and an LDG RU 1:1 unun. % As an example, a 28-31 foot wire will typically allow 40 thru 10 meter coverage and a 43-50 foot wire will provide access to 80 thru 10 meters. Stacked coreswithwinding configured as 49:1auto transformer. 1. So, having nothing better to do one day, I re-did the calculations going out to 500 feet. Antenna Design Start winding the toroid with the twisted wires at loop #1 (see schematic below). (Also note that here may be instances where the suggested lengths may not work exactly due tothe many variablesin the surroundings of the antenna, wire length variances,your tuner, it's height above ground, it's construction,etc. Windings are inserted into Teflon tubes increasingtotal breakdown to 10,000 volts. Superglue 2 toroids together. Super Bullet Features: - Uses proprietary broadband impedance transformer design for maximum bandwidth with SWR < 2 from 1.8-61 MHz for 1500 Watt model and 1.8-30 MHz for 3000 watt model The length of enamelled copper wire per winding for the T-200-2 powdered iron toroid core is determined by length per winding = 50mm per turn plus 250mm tails. So, if you connect a length of wire that presents an impedance of about 450 to the input, you'll get an impedance of about 50 on the output. This Balun Designs unit is replacing an MFj 1982 HP EFHW balun that was DOA when it arrived last May. Q Weight: 0.380 lbs. JavaScript is disabled. /Contents 5 0 R Therefore, we came up with the following numbers to avoid (IN FEET): These lengths in the table beloware the culprits that cause all of the trouble when using random lengths. However, the list has been revised and is good for wires as long as 500 feet. << A small ring terminal for 14ga wire that fits these screws would be helpful too. /BitsPerComponent 8 SWR was good after cutting the wire to appropriate length. Experimenting by slightly changing the wire length (+ or-) is encouraged to provide best overall performance. Thanks for your answer,I will probably go with the 9:1 then. This type of antenna is very easy to install because there is no need . /Kids [ 4 0 R ] The counterpoise wire, This transformer is designed to be used with an end fed, Approx. transmit frequency the impedance is so high that tuners in most rigs Step 1: Drill holes for and install the SO-239 or BNC connector, the stainless steel machine screw antenna connector and the ss machine screw ground connector. The ratio doesn't need to be 49:1 2,400 ohm either, other ratios will transform to other impedance. wire is at least 1/4 wavelength. 32.00. Allows the internal tuner of most rigs to tune remotely mounted single wire antennas. results. Even better would be shortening to 53'. Connect this ring terminal to one of the SO239 chassis bolts. Technical specification : Type : 49:1 Unun Frequency : 1.8 MHz - 7.3 MHz Turns ratio: 1:7 Impedance ratio: 1:49 Input Impedance: 50 Output Impedance: 2450 Power Handling (CW/SSB/ Digital Modes) : 2Kw of peak power / DM Modes 500 watts Core Type : 3 x FT240-43 by Fair-rite Co. Wire type: Enamel copper wire 2.0 mm (AWG 12) Assembled and tested.