Dipole SWR

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RogerD
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Re: Dipole SWR

Post by RogerD »

A dipole at resonance is about 72 Ohms IIRC, so with 50 Ohms feeder you'll get at worst a mismatch of just under 1.5:1 - barely worth worrying about most of the time.

The 4:1 balun is most often used with balanced 300 Ohm antennas (like the FOLDED dipole) to bring them down to 75 Ohms for an unbalanced (coax) feeder at that impedance.

Using the 4:1 balun "just in case, for safety" will cause more problems than you were trying to safeguard against :geek:
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spanerman
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Re: Dipole SWR

Post by spanerman »

thanks for the help, the Windom in working brilliantly on 40 20 11 and 10m

need to finish it off with the 1:1 choke :D

Sam.
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HomerBB
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Re: Dipole SWR

Post by HomerBB »

RogerD wrote:A dipole at resonance is about 72 Ohms IIRC, so with 50 Ohms feeder you'll get at worst a mismatch of just under 1.5:1 - barely worth worrying about most of the time.

The 4:1 balun is most often used with balanced 300 Ohm antennas (like the FOLDED dipole) to bring them down to 75 Ohms for an unbalanced (coax) feeder at that impedance.

Using the 4:1 balun "just in case, for safety" will cause more problems than you were trying to safeguard against :geek:
The only suggestion I proposed was to use a coax choke (1:1) to maintain a control over potential CMC. I also said that my experience is that a coax choke - called ugly balun by some - smooths out the SWR curve in virtually all applications I've used it. I'm sorry I wasn't more clear on that.

I agree with everything you've said.
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