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frequency a bit lower because I'm a CW op and don't care much about ssb above 7250. I found that lengthening the driven element 3 inches from the stated directions for 7080 worked perfectly. The tuning is very broad. I hoisted the driven element up about 30 feet and found the resonant frequency a bit low but thought I would go with instinct which turned out to be right on the money. If you shorten the driven element by 6 inches from the length suggested for 7080 you should be just fine. It won't make any difference in SWR if it's 1.2 or 1.1 to 1 (hi). Mine is very flat up to about 7220 from 7000. I checked the driven element and then when the whole antenna was assembled hoisted it up as well. I found that the resonant frequency was low due to proximity to the ground. You won't get a decent reading until you get it up in the air. But, again, the tuning is very broad so you don't need a micrometer to measure the elements. It's better to cut them long and then if you absolutely need to, trim back. But again, don't be fooled by readings close to the ground. A word of caution. If your friend has a Packet or other signals being transmitted on 2 meters while you are measuring or otherwise using an MFJ antenna analyzer, turn off the transmitter. I found it was getting into the MFJ and causing all sorts of erratic readings. BTW, I've had the antenna up since May 23. Since then, I've worked 120 counties and 36 zones (I need 2, 12, 22 and 23). I'm only running 200 watts! Enjoy the antenna -- it's the best I've ever had on 40. Pete, W1RM -----Original Message----- From: Paul B. Peters, VE7AVV [mailto:ve7avv@shaw.ca] Sent: Sunday, October 12, 2003 3:29 PM To: Force12Talk@qth.com Subject: [Force 12 Talk] Tuning a Magnum 240N? I'm helping a friend assemble (and tune) a brand new Magnum 240N. To say that I have found the printed instructions hard to follow as it relates to tuning this antenna is a real understatement -- I could really use some assistance from the group. Here is the situation: The owner wants to operate from 7050 to approximately 7250 -- so the mid point would be 7150. With that in mind, I have the following questions: 1) What are the tip lengths for the Reflector & Director, when a center operating frequency of 7150 is required? 2) Are the two (2) individual element final resonant adjustments with a meter done with individual elements or with the assembled antenna raised above ground? 3) Tuning of the Reflector is done with the balun and feed line attached to it and the Director "open", according to the manual. Is the Reflector also "open" when adjusting the coil on the Director for lowest SWR? Asking this question suggests that the answer to 2) (above) is that the entire antenna is assembled above ground for checking rather than the individual elements. I would appreciate hearing from anyone who has this exact antenna -- maybe you've been through this same series of questions and hopefully found the answers. The final resting place for this new antenna will be atop a brand new US Towers 88' crank-up. 73 de Paul, VE7AVV StoneyGround Station -|<*><*>||<*><*>||<*><*>||<*><*>||<*><*>||<*><*>||<*><*>||<*><*>|- "All email from this address is checked by Norton AntiVirus 2003" -------------------------------------------- Force12Talk mailing list provided as a service by Force 12 Antennas, Inc. Force12 Web Site: http://www.force12inc.com To Submit Message to the List: Force12Talk@qth.com To unsubscribe and view the Message Archive: see http://qth.com/force12/list For problems with the list: contact force12@qth.com -------------------------------------------- Force12Talk mailing list provided as a service by Force 12 Antennas, Inc. Force12 Web Site: http://www.force12inc.com To Submit Message to the List: Force12Talk@qth.com To unsubscribe and view the Message Archive: see http://qth.com/force12/list For problems with the list: contact force12@qth.com |
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