MFJ 1769 - ROTATABLE DIPOLE, 4-BAND,(20,15,10,6M) manual
MFJ 1769 is a 4-band rotatable dipole antenna designed for 20, 15, 10, and 6-meter bands. It's compact and lightweight, making it suitable for small roofs, townhouses, apartments, and condos. The antenna can handle up to 1500 Watts SSB/CW on 20, 15, and 10 meters and 1500 watts on 6 meters. Its bidirectional pattern helps reduce QRM/noise while maximizing signal strength in desired directions, enhancing DX capabilities. With a turning radius of just 13 feet, it can easily be rotated using a lightweight TV rotator like the HyGain AR-35.
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4-BAND ROTATABLE DIPOLE MFKJ-1769 Rotatable Dipole Instructions MFJ-1769 4-Band Rotatable Dipole INTRODUCTION The MFJ-1769 is a 26 foot 20-, 15-, 10-and 6-meter full legal limit rotatable dipole that is inconspicuous and low profile, making it almost invisible from across the street. With its 13-foot turning radius and 8-pound weight, it fits on even small roofs and is perfect for town houses, apartments and condos - and can easily be turned by a lightweight TV rotator such as the HyGain AR-35. If necessary, the 1769 can even be mounted inside an attic! And this antenna is no wimp! lts bidirectional pattern can help reduce QRM and/or noise while maximizing your signal in the directions that you want -- so you can work some real DX. High efficiency traps provide operation up to a full 1500 Watts SSB/CW on 20, 15, and 10 meters. Stub matching is used on 6 meters for 1500 watt operation on this band as well. The MFJ-1769 is built-to-last — using an incredibly strong solid rod fiberglass center insulator and 6063 T-6 aircraft strength aluminum tubing for the radiator. And it assembles in about an hour. WARNING: Improper installation and assembly can be hazardous! Read these instructions thoroughly before attempting to assemble, install or operate this product! High power transmitting devices produce voltages that can cause severe burns or other injuries. SPECIFICATIONS Electrical Specifications Power | Band CW SSB 2:1 SWRBW Gain Front-to-Side 20m 1500 1500 200 KHZ OdBd 20dB 15m 1500 1500 400 KHZ 0dBd 20dB 10m 1500 1500 1.1. MHZ 0dBd 20dB бт 1500 1500 600K hz 0dBd 20dB Mechanical Specifications Mast Size: 1- to 1-1/2” diameter Overall Length: 26 feet Turning Radius: 13 feet Weight: 8 pounds Wind Load: 1 square foot MFJ-1769 Rotatable Dipole Instructions CHOOSING A LOCATION FOR THE ANTENNA For best performance on receiving and transmitting, mount the antenna in a clear location above or away from buildings, towers, feedlines, utility wires, and other antennas. While your own ingenuity and particular circumstances will determine the final mounting method, we'll pass along a few ideas for both permanent installation and portable operation. e Never mount this antenna in a location that will permit unsuspecting people to come in contact with any part of the antenna. * Never mount this antenna where a mechanical failure might allow the antenna to contact power lines or other utility wires. * Always ground the feedline to a good earth ground at the point where it enters a building for lightning protection. WARNING: Always mount this antenna so that it is out of the reach of adults and children. Contact with the antenna during operation can result in severe RF burns. Permanent Installation The ideal installation 1s a rigid pole or roof mount that puts the antenna completely in the clear. If the ideal installation 1s not possible, choose the best compromise. TV mast, heavy-duty rigid electrical conduit, and steel water pipes are suitable mast materials. This antenna will mount on masts between 1 and 1-1/2" OD. Do not use soft or thin wall masts. Portable Operation The MFJ-1769 may be disassembled as necessary for transporting to a temporary location. Use a permanent marking pen to mark the tube positions for easy re-assembly. Even for temporary or portable operation, do not be casual about selecting a suitable mast. If the antenna falls, 1t will be damaged and may cause serious injury. Whatever type of installation you choose, remember that the antenna should be installed where it can never be contacted by people or animals or come in contact with power lines. TOOLS AND TIME REQUIRED FOR ASSEMBLY The estimated assembly time 1s two hours. Antenna assembly requires the following hand tools: e #2 Phillips screwdriver e 5/16" nut driver for hose clamps. e Safety glasses. It 1s also convenient if you have a short (6-8') temporary mast (1 to 1-1/2" OD) for temporary antenna mounting for preliminary resonant frequency checks. MFJ-1769 Rotatable Dipole MFJ-1769 PARTS LIST As you unpack your antenna, verify that the following parts are supplied: Item Part Description QTY Part No. ] 1-3/8 x 12” AL Tube 2 175168 2 1-1/4 x 12” Fiberglass Rod 1 811-1812 3 4-20 x 1-3/4 bolt 2 505763 4 Ya split lock washer 2 561177 5 /4-20 hex nut 2 554099 6 /4” Solder Lugs 2 677556 7 640 U-bolt Set 1 758-9200 9 7/16 x 28” AL Tube 2 178558 10 55” Treaded Rod 2 758-8253 11 Al “LL” Stabilizer Bracket 2 805-1796-7 12 1-1/8 x 38” AL Tube 2 190307 13 1 x 6-1/2” AL Tube 2 190605 14 1-1/4 x 48” AL Tube 2 190900 15 Fiberglass Stabilizer 2 807-1796-6 16 Al Stub Channel Bracket 2 807-1796-5 17 Tubing Clamp, #6 2 358756 18 Tubing Clam, #10 6 358757 19 Tubing Clamp, #16 8 358758 20 6-32 kep nut 6 705-06328 21 6-32 x 3/8” screw 6 656-03755 22 71/16” Cap Plug 2 455644 23 10-32 hex nut 4 705-10328 24 #10 lock washer 2 711-1037S-EX 41 Trap, Beam, DE15M 2 878637 43 Trap, Beam, 10M 2 878749 Instructions For installation, you will need some items not supplied with the antenna installation kit: о A 6'-8' ngid mast or other mounting pipe between 1" and 1.5" outside diameter is convenient for a preliminary test of resonant frequencies. Suitable materials include TV mast sections, galvanized iron pipe, or heavy duty rigid conduit. e Quality low-loss 50-Ohm coax with a PL-259 from antenna to transmitter. * An Antenna Analyzer (MFJ-259B or similar), or SWR meter and transceiver SAFETY PRECAUTIONS: WARNING! You can be killed if the antenna, feedline, or the equipment used to install the antenna accidentally contacts any utility lines. Never install an antenna near power lines! MFJ-1769 Rotatable Dipole Instructions 1. Be careful when carrying and installing the antenna. It 1s heavy enough to cause you to lose your balance if it is handled too casually or if the antenna is snagged on anything. 2. Mount the antenna high enough so that it 1s out of reach. The ends of the antenna can cause eye injury, serious RF burns or both. 3. Make sure that the mast is sturdy enough to support the 8-pound weight and the wind loading of approximately 1-square foot. ASSEMBLY and INSTALLATION PROCEDURE Refer to the figures in this manual during assembly. Assembly consists of putting together the center insulator assembly, then connecting the aluminum radiating elements to the center insulator assembly, and finally attaching the feedline. After the antenna is assembled and adjusted for resonant frequency and SWR, it can then be mounted on a tower or rooftop. WARNING: Wear safety glasses whenever working with this antenna. Step-By-Step Procedure |) Find a flat work area with the necessary clearance for assembly. The 1769 is easily assembled on the ground. 2) After examining the antenna parts, gather the following tools needed for assembly: e Small (47-6) adjustable wrench OR 5/16" nut driver for hose clamps and 7/16" open end wrench for center insulator bolts. e Safety glasses. 3) Loosely assemble the U-bolt set to the 1-1/4” fiberglass rod using supplied hardware. The nuts will be tightened when the antenna is mounted on the mast. See Figure 1. U-Bolt set >| | a al Fiberglass Rod IV nn > ЕЁ a (2 ples) Figure 1: Center Insulator Assy — Top View 4) Slide the 1-3/8 x 12” aluminum tubes over each side of the center insulator assembly. Insert the 14-20 bolts through the aluminum tube/fiberglass assembly. Add the 74-20 split MFJ-1769 Rotatable Dipole Instructions lockwashers and nuts and fasten loosely, as the feedline will be connected to this hardware later on. See Figure 2. (COS ВЫ 12” AL (2 ples) Fiberglass Rod >t > НЕ 14” Solder = — 7-20 hdwr Lugs (2 plcs) Boles (2 ples) Figure 2: Center Insulator Assy — Top View 5) Shde the two 1-1/4 x 48” aluminum radiator tubes into each of the 1-3/8” x 12” aluminum tubes mounted to the 1-1/4” x 12” fiberglass rod. The 48” aluminum tubes should slide up against the fiberglass rod. Clamp the 1-1/4 x 48” aluminum tubes to the 1-3/8 x 12” aluminum tubes using #16 tubing clamps as shown in Figure 3. 1-1/4” Fiberglass 1-3/8x 12” AL Tube 1-1/4x48” AL Tube Tube (< pies) (2 ples) Ss = IMM rr" zz E, - i hos a nk 4-20 hdwr — (end view) w *16 Tubing N Clamps Figure 3: 48” Radiator Tube to Center Insulator Assembly 6) Assemble each side of the dipole as shown in Figure 4. The item numbers in Figure 4 correspond to the item numbers on the parts list. 14 22 9 17 41 18] 18 43 18 12 19 14 Ц су [92475 — < di > MID 424.75" Pp 7 00” «> < 48" > py [924.75 > 7.00” M > — ae > a, а À SRE Figure 4: Element assembly details This total length from feed bolt is the important parameter MFJ-1769 Rotatable Dipole Instructions 6 Mtr stub ASSEMBLY and INSTALLATION 7) Assemble the two small "L" brackets to the two long fiberglass insulators with 6-32 x 3/8" screws (3 each) and the 6-32 kep nuts (3 each) as shown in Figure 5. Hole for 6 or 2 if meter stub 6-32% 3/6 >El El <—9.6' Aluminum и screws (3) L-bracket CTT | Ei | Fiberglass insulator 6-32 nuts (3) Figure 5 8) Open up two #16 hose clamps and install then over the HF beam’s driven element as close to the inside ends of the driven element as possible. Clamp the two aluminum stub channel brackets (one on each radiator) as shown in Figure 6. Da brkt 55” threaded rod #10 nuts (2 ( ) НЕ Ta — = | AL brkt — 9 | 4 35" »|«- —20” — > = — = | Center Insulator O — HF Beam Driven Element Ш к > h Balun I Figure 6: 6 meter stub assembly and mounting 9) Open up the remaining two #16 hose clamps (one on each radiator), clamp the fiberglass insulators so as to support the 55” threaded rods. Position the insulators as shown in Figure 6. 10) Mount the two stubs by threading a 10-32 x 3/8" nut 1/2" near the end of the threads. Add a second nut and lockwasher to sandwich the bracket between the two nuts, leaving no more than 4” of threaded rod exposed beyond the aluminum bracket. See Figure 6. 11) Strip four inches of insulation from the end of your coax feedline. Separate the braid from the center conductor and install the '4” solder lugs on the shield and center conductor wire (solder in place). Coat the leads liberally with Liquid Electrical Tape “ and let dry. Once the Liquid Electrical Tape!" is dry, connect the feed to the 74-20 hardware as shown in Figure 7. MFKJ-1769 Rotatable Dipole Instructions Note: The 1769 is a balanced antenna, and as such should be balun fed. An effective balun can be created by coiling the coax feedline into 6-turns with a diameter of 4-6 inches as close to the antenna as possible (the coil should be no more than about 12-inches from the antenna). Do not scramble-wind the turns. Le., preferably wind the turns side-by side. Finish the balun by holding the turns together with black tie-wraps. 7 1-3/8x 12” AL (2 E bea | - Fiberglass Rod Slot > = ‘ /” Solder — > ~~ (2 plcs) | Balun Figure 7: Balun/Feed Connections = Y _ Y4-20 hdwr Coax/Balun feed (2 ples) wire (2 plcs) 12) Double check the tightness of all the hardware. 13) Tune the antenna as discussed in the next section. 14) Mount the antenna in the final location. Slight re-tuning may be necessary. FREQUENCY AND SWR ADJUSTMENT An SWR analyzer such as the MFJ-259B or equivalent is highly recommended when tuning the 1769. While a transceiver and SWR meter can be used, an SWR analyzer will significantly decrease the time and effort necessary to tune the antenna. The entire antenna must be accessible during tuning and testing. Because of the non-criticality of 6-meter tuning, final tuning of the 6-meter resonant frequency can be made with the antenna mounted 5-6 feet above ground. During tuning, feed the antenna with a reasonably short length of good quality 50 ohm coaxial cable and a balun to ensure proper results. If using a transceiver and SWR meter, set the transceiver to the lowest power possible when making measurements. MFJ-1769 Rotatable Dipole Instructions Tuning the Antenna 1) Adjust the 6-meter resonant frequency first. Then proceed to 10-meters, 15-meters, and finally 20-meters. The SWR should be below 2:1 at resonance on each band. 2) The six meter band 1s tuned by lengthening or shortening the threaded portion of the stubs. This adjustment 1s very coarse. If the frequency is still too low with the stub element extension at a minimum, the unthreaded ends of the stubs can be trimmed. NOTE: The six meter stub covers 50 to 54 MHz. Resonance at 50.15 MHz (popular SSB part of the band) typically requires the full 55-inch stub lengths (flat side of aluminum mounting bracket to end of stub). 15) If available, mount the antenna on a short temporary mast 6-8 feet above the ground and check the resonant frequency of the antenna on 20-, 15-, and 10-meters. Note: The resonant frequency will increase about 50 kHz on 20 meters, 75 kHz on 15 meters, and 100 kHz on 10 meters when the antenna 1s raised to 20-feet or higher. 16) If necessary, adjust the resonant frequency on the three bands. Start with 10-meters by adjusting the innermost tubing lengths, then move to 15-meters (adjust the spacing between the two traps), and finally 20 meters (adjust the length of the end tubes). Shortening the tubes Increases the resonant frequency, and lengthening the tubes decreases the resonant frequency. Note: Changing the resonant frequency of a higher frequency band will also change the resonant frequency of the bands below the changed band. I.e., increasing the resonant frequency of the 10-meter element will also increase the resonant frequency of both 15- and 20-meters. 17) Mount the antenna in the final location. GROUNDING CONSIDERATIONS Although this antenna 1s designed to operate efficiently without the requirement of an earth ground, safety grounding must still be provided to protect equipment, property and persons from the hazards of lighting strikes and other weather related electrical discharges. Adequate protection can be accomplished by grounding the shield of the coax to a good earth ground where it enters the building, or directly burying the cable in the earth for several feet betore 1t enters the building. For maximum lightning protection, the coaxial cable should be totally disconnected from the station during threatening weather conditions. MFJ-1769 Rotatable Dipole Instructions A less effective method of protecting station equipment is to install an in-line coaxial lightning arrestor with a heavy duty ground wire to a suitable earth ground, or a safety switching system as part of the basic ham station equipment. MAINTENANCE Your antenna is constructed of heavy duty non corrosive materials and should withstand normal climates for many years. The use of some type of coaxial connector moisture protection 15 recommended at the balun/coax connection, and also around the center-feed connections, especially in coastal areas where salty mist 1s commonplace. GE makes a pure, silicone grease called "SILICONE DIALECTRIC COMPOUND" that can be applied SPARINGLY to the threaded area of the female connector. This compound, or even a clear silicone heatsink compound, will prevent moisture from entering the connector through the threads and protect the connectors from corrosion. This is the same type of sealer that commercial antenna installers and CATV companies use with great success. Plast-Dip'* and Liquid Electrical Tape'", available at your local hardware store, also do an excellent job of insulating/waterproofing connectors, and can be easily peeled off when desired. A less desirable, but still adequate sealer is the automobile seam sealer commonly sold as "coax seal". This 1s a semi-pliable black or white sealing compound. When installing any "coax seal", NEVER completely cover the barrel of the coax connector. The sealer should ONLY be placed near the junction of the threaded part of the chassis connector and the knurled area of the male connector. This will leave the bottom of the male outer sleeve open and permit the connector to "breathe" so 1t does NOT collect moisture! TECHNICAL ASSISTANCE If you have any problem with this product, first verify that you have assembled, installed and tuned it correctly. If your problem is not solved by following the manual you may call MFJ toll- free at 1-800-647-TECH (8324) or FAX to 601-323-6551, or TELEX 53 4590 МЕЛ УТКУ. Outside of the continental U.S.A. 601-323-5869. Please have your manual and all information on your station handy so you can answer any questions the technicians may ask. You can also send questions to MFJ, P.O. Box 494, Mississippi State, MS 39762. Send a complete description of your problem, an explanation of exactly how you are using your unit and a complete description of your station. 10 LIMITED 12 MONTH WARRANTY МЕ Enterprises, Inc. warrants to the original owner of this product, if manufactured by MFJ Enterprises, Inc. and purchased from an authorized dealer or directly from MFJ Enterprises, Inc. to be free from defects in material and workmanship for a period of 12 months from date of purchase provided the following terms of this warranty are satisfied. 1. 10. 11. The purchaser must retain the dated proof-of-purchase (bill of sale, canceled check, credit card or money order receipt, etc.) describing the product to establish the validity of the warranty claim and submit the original or machine reproduction of such proof of purchase to MFJ Enterprises, Inc. at the time of warranty service. MFJ Enterprises, Inc. shall have the discretion to deny warranty without dated proof-of-purchase. Any evidence of alteration, erasure, or forgery shall be cause to void any and all warranty terms immediately. MFJ Enterprises, Inc. agrees to repair or replace at MFJ's option without charge to the original owner any defective product under warrantee provided the product is returned postage prepaid to MFJ Enterprises, Inc. with a personal check, cashiers check, or money order for $7.00 covering postage and handling. This warranty 1s NOT void for owners who attempt to repair defective units. Technical consultation is available by calling the Service Department at 662-323-0549 or the MFJ Factory at 662-323-5869. This warranty does not apply to kits sold by or manufactured by MFJ Enterprises, Inc. Wired and tested PC board products are covered by this warranty provided only the wired and tested PC board product is returned. Wired and tested PC boards installed in the owner's cabinet or connected to switches, jacks, or cables, etc. sent to MFJ Enterprises, Inc. will be returned at the owner's expense unrepaired. Under no circumstances 1s MFJ Enterprises, Inc. liable for consequential damages to person or property by the use of any MFJ products. Out-of-Warranty Service: MFJ Enterprises, Inc. will repair any out-of-warranty product provided the unit 1s shipped prepaid. All repaired units will be shipped COD to the owner. Repair charges will be added to the COD fee unless other arrangements are made. This warranty is given in lieu of any other warranty expressed or implied. MFJ Enterprises, Inc. reserves the right to make changes or improvements in design or manufacture without incurring any obligation to install such changes upon any of the products previously manufactured. All MF] products to be serviced in-warranty or out-of-warranty should be addressed to: MFJ Enterprises, Inc., 300 Industrial Park Road Starkville, Mississippi 39759 USA and must be accompanied by a letter describing the problem in detail along with a copy of your dated proof-of-purchase. This warranty gives you specific rights, and you may also have other rights which vary from state to state. ">

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