12/29/2022 0 Comments 50 ohm hardline coaxWhen you talk about 50-60feet high do you mean elevation above the closest surface or the earth? With a single dipole, impedance and phase are not a big issue. If one Yagi hogs power due to a mismatch, this improper phasing may wreak havoc on the overall pattern. I really posted the 75:50 ohm, 1/12 wave unun for use when matching multiple elements or Yagis - to give perfect power divisions and transfers. Be sure to wind ~ 10-12 turns of coax onto a 3-4" diameter (PVC pipe) to act as a choke at the feedpoint. It's really not that critical because it is a low band (75M) and a single element. I agree with Steve that the dipole will be a FB match for 50 ohm coax on 75M. it will probably only be a couple feet off the surface of the roof. When you talk about 50-60feet high do you mean elevation above the closest surface or the earth? i plan to mount the antenna on the roof of my studio which is on the second floor of a two story strip mall. should i still use a 1:1 balun to match the balanced antenna to the unbalanced coaxial cable? Thanks for the tips! thats one less thing to worry about. On 75 meters, if it is less than 50-60 feet high, it will probably have a feedpoint impedance closer to 50 Ohms than 75.Įven if it did turn out to be 75 Ohms, the mismatch is not worth worrying about. Your dipole will not be in free-space but over real ground. Yes, a dipole has a feedpoint impedance of 75 Ohms in free-space. You will probably not need any such matching for your dipole. If so, would the transformer K1JJ mentions in this thread be appropriate for my situation? i assume i need some sort of 75ohm to 50ohm impedance matching between either a 75ohm coaxial line and the transmitter or between a 50ohm coaxial line and the halfwave dipole. 8) i plan to use a half-wave dipole with a 5w transmitter for QRP CW on the 80m band.Īs i understand it a halfwave dipole is ~75ohm impedance, coaxial cable comes in 75ohm or 50ohm impedance, and the linear amp i am looking at expects a 50ohm load. i'm planning out how i want to setup my station once i get a chance to get my license. Sorry to resurrect an old thread but this seems like the sort of technique i might need to use when i setup my station. Re: How to MATCH a 50 Ohm antenna/coax to 75 ohm Coax/hardline
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