background image

MFJ-1768 Dual Band Yagi                                                                       Instruction Manual 

8  

 
Adequate protection can be accomplished by grounding the shield of the coax where it enters the 
building to a good earth ground or directly burying the cable in the earth for several feet  before it 
enters the building.  The coaxial cable should be totally disconnected from the station during 
threatening weather conditions for maximum lightning protection. 
 
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 is 
recommended at the bottom coax connection and also around the center-feed connections, especially in 
coastal areas where salty mist is commonplace. 
 
GE makes a pure silicone grease called 

"SILICONE DIELECTRIC COMPOUND"

 that can be 

applied SPARINGLY to the threaded area of the female connector. This compound, or even a clear 
silicone heat sink 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. 
  
A less desirable, but still adequate sealer is the automobile seam sealer commonly sold as "coax seal". 
This is a pliable black 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 it does NOT collect moisture! 

Technical Assistance 

 

If you have any problem with this unit first check the appropriate section of this manual. If the manual 
does not reference your problem or your problem is not solved by reading the manual you may call 
MFJ toll-free at 1-800-647-TECH (8324).  Outside of the continental U.S.A. call 601-323-5869.  You 
will be best helped if you have your unit, manual and all information on your station handy so you can 
answer any questions the technicians may ask. 
 
You can also send questions by mail to MFJ Enterprises, INC., PO. Box 494, Mississippi State, MS 
39762; by FAX to 601-323-6551 or on Compuserve at [email protected].  Send a 
complete description of your problem, an explanation of exactly how you are using your unit and a 
complete description of your station. 
 
 

Содержание MFJ-1768

Страница 1: ...ruction Manual Table of Contents Introduction 2 Choosing a Location for the Antenna 2 Tools and Time Requirements 3 MFJ 1768 Parts List 3 Safety Precautions 3 Assembly and Installation 4 Tuning 7 Grounding Considerations 7 Maintenance 8 Technical Assistance 8 ...

Страница 2: ... band antenna there is no need to switch antennas when changing bands With the use of a duplexer such as the MFJ 916 you can connect two different radios two different bands to the MFJ 1768 at the same time Choosing a Location for the Antenna The MFJ 1768 can be mounted on any 1 to 1 1 2 mast conductive or non conductive capable of supporting the weight of the antenna and the torque developed by t...

Страница 3: ...One bag containing the following hardware Twenty 3 16 ID insulators 30 push nuts 3 16 ID Two 1 1 8 red end caps One U bolt and saddle clamp assembly Push nut assembly tool Two capacitor thin plates for 2 m elements Two 4 40 x 1 2 SST screws Ten 4 40 SST nuts One 1 1 8 diameter 6061 T6 aluminum tubing boom Safety Precautions WARNING This antenna is an electrical conductor Contact with power lines c...

Страница 4: ...nstallation During assembly of this antenna refer to figures in this manual and the picture on the front cover The assembly instructions tell you step by step how to install the insulators the driven and parasitic elements and the U bolt assembly All parasitic elements for 2 meter and 70 cm band are color coded at their ends and alphabetically labeled on figure 1 and on figure inside front cover t...

Страница 5: ... start the assembly of the driven elements as follows A The 2 meter driven element Align the holes drilled on the end of a 19 1 4 x 1 4 tube with the 4 40 screws located on the rear end of the feed plate see figure 3 for exact location Insert the 4 40 screws into these holes Thread 4 40 nuts over the two screws and tighten to ensure good connections Repeat the same procedure for the remaining 19 1...

Страница 6: ...or section 7 and 8 refer to figure 1 figure 4 and figure 5 while assembling 7 Insert element A black end from GROUP 1 into its designated hole in the boom as shown in the figure on the inside front cover Assemble another push nut from the other side see figure 4 and figure 5 and slide it until it reaches the 3 16 black insulator Make sure that the element is secured in place with minimum free play...

Страница 7: ...e boom and run it along the permanent mast Hold it in place using either electric tape or black cable ties Tuning The MFJ 1768 is pre tuned on both bands additional tuning is not required The antenna bandwidth is very wide it covers the entire 2 meter and 70 centimeter band with an SWR less than 2 1 Grounding Considerations Although this antenna is designed to operate efficiently without the requi...

Страница 8: ...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 A less desirable but still adequate sealer is the automobile seam sealer commonly sold as coax seal This is a pliable black sealing compound When installing any coax seal NEVER completely cover the barrel of the coax connector Th...

Страница 9: ... cashiers check or money order must be provided to cover postage and handling 4 This warranty is NOT void for owners who attempt to repair defective units Technical consultation is available by calling 601 323 5869 5 This warranty does not apply to kits sold by or manufactured by MFJ Enterprises Inc 6 Wired and tested PC board products are covered by this warranty provided only the wired and teste...

Отзывы: