Thanks Marconi for this video. I followed this video and could calculate 1/4 wave resonant jumper. I set the analyzer in Impedance R & X on 27,205 KHz.
( Channel 20 ). In order to use this method, one must cut the coax longer like Dr_DX said, to cut coax 20% longer ( I recommend to use formula first and then add the 20% to play with it) and cut little by little in order to find resonance.
I think it is more convenient to calculate a 1/4 wave length ( less hassle and cutting valuable coax ) and then multiply it by the odd or even multiple you will need.
When R = 0 and X = 0 then I began to cut little by little until X disappeared like in the video.
Resonant 1/4 wave jumper length at 27,205KHz calculated by my MFJ-269 C analyzer is 7.25’ = 7’,3” long. Using formula give me 7.5926 = 7’,7”. If I have around 50 feet from antenna to station, it would be an important difference to affect resonance in the coax cable.
If I am going to make a jumper from antenna to station, ( 50 feet distance ) should cut the cable by odd or even length ? ( I plan to use 7.25’ given by the analyzer).
Is it right my thinking of multiplying by X multiples of the result given by the analyzer?
For sure I know coax length is not important as long as antenna is resonant on the frequency you want it to be, but sometimes cutting coax for resonance as well, can resolve some SWR issues like I am having right now with my Vector 4000.
By the way, Bob85 said to use choke ( I used a line isolator ) but adding a line isolator got things worse. I could not get SWR lower than 1.5 and bandwidth was higher. From a SWR of 1.3 and a BW of 2,070 KHz @ 16 feet high above roof, by adding the line isolator,SWR went up to 1.5 BW went up to 2,470 KHz @ 16 feet high above the roof.
