Low impedance on Gainmaster 5/8 antenna

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chr0nik
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Low impedance on Gainmaster 5/8 antenna

Post by chr0nik »

Hi,

I'm relocating some of the antennas that I have and I came across the Gainmaster that I have on a 6m aluminium pole (on a 2m high extension roof) and I plugged it to my meter and it shows as having between 15 to 25 omhs across the 11m band. The coax used is 3m long RG213 cable and the antenna is isolated from the pole.

I'm sure this is not normal as it should be 50omhs but I'm unsure of what might the issue be as I would need to take it all down and re-test.

Also, I have an EFHW for 11m and I'd like to know if this would perform better than a GM if positioned horizontally at around 6m high.

Thanks!
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ch25
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Re: Low impedance on Gainmaster 5/8 antenna

Post by ch25 »

Should be 0 when measuring with DMM.
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InTheClouds
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Re: Low impedance on Gainmaster 5/8 antenna

Post by InTheClouds »

DMM = digital multi meter... are you using an analyzer to read the impedance ?

Performance for what ? Local, European DX or long haul DX.

Local = GM, Short DX Euro about the same assuming your EFHW is cut ONLY for 11m and your nulls (ends of antenna) are facing North - South.
Long haul I would go for the GM unless interference from domestic sources are causing you a lot of S meter noise floor. That is likely to drop 2-3 S point on the horizontal.
paulears
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Re: Low impedance on Gainmaster 5/8 antenna

Post by paulears »

If you put a normal multimeter on many 50Ohm antennas it reads a direct short circuit - maybe .5 Ohms, for lightning protection. Do you have a VSWR meter? this uses what goes out of the radio into the antenna and compares it to what comes back as a reflection. The better match the antenna has the more goes out and the least gets reflected. You cannot use a multimeter - it doesn't work because we're talking RF energy not resistance of a cable.
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