I am building a 6 m 2 el Yagi dK7ZB design and it is matched with a transformer made from 75 Ohm coax. 2 stubs of 1/4 Lambda in parallel. I tohought I could ?put a 28 Ohm resistor replacing the radiator ?and then have 50 Ohms on the Nano VNA at 50 Mhz resonnance. ?But that is not, what I see. ?Resonance is 37.8 Mhz ?at 47 Ohms resitance . At 50 Mhz resistance would be 38 Ohms and SWR 1,4. ?Prior to that I had mesured the coax with a velocity factor of 1 and could calculate a Velocity factor of 0,63 for the cable which is an unknown TV cable. Then calculated the lenth with that VF so I thought I should not be too far of. ? Any suggestions ?
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Marin
DK3 UW
