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  #1  
Old 03-22-2008, 07:12 PM
M0TIU M0TIU is offline
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Join Date: Jan 2008
Posts: 2
Default MFJ 1798 vertical antenna

Has anyone experienced difficulty in tuning this antenna. I have been using and antenna analyser and have horrendous difficulty in tuning the bands on it.
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  #2  
Old 08-24-2008, 10:51 PM
KC7NOA KC7NOA is online now
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Join Date: Mar 2001
Location: Spokane Valley
Posts: 35
Default Mfj-1798

I have read that the reason that the antenna is horrible to tune is to two problems, one -- the coax connector at the base of the antenna has a broken center connector at the pl-259, the other affects the lower bands, ie - 30m down, the 4 similar capacitors on the pcb at the top of the antenna( that has the tap for 2-meters) needs to be replaced with 390pF that are RF rated. I have Bought some off of ebay and still waiting for delivery.

The symptoms on 75/80 and 40 is that as you get close to the resonance say at 3.950 the impedance goes up above 3:1 ...

Ill know more for sure when my capacitors show up and i install them ... im also going to try to add 160M by adding 3/4Y to the end of the loaded section.

KC7NOA
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