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antenna length?

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unidcom

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Aug 10, 2006
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hii
What is the length i neet to set up(to cut) my motorola MAXTRAK\LTS2000 antenna for best transmitting and best receiving for 164MHZ?
did there any formula to calculate this?

thanks..
 

jhooten

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Those appear to be the whips and springs from a 5/8 wave antenna there should be more pieces.

Do a web search for Larsen antenna web site. They have cutting charts in the tech section.
 

kf4lne

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A cutting chart is great, but the best way to do it is to cut it close, but long and trim to a match using a SWR meter. For receiving only, you can just cut it to a length based on 234/MHz*12=inches to get a 1/4 wl measurement. (234/162.4=1.44ft*12=17.29in)
 

mcema699

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Mar 11, 2005
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1/4 wave?

Be sure those aren't loading coils (gain antenna) before you use the formula above. The chart for the particular antenna is the best bet and swr for xmit.
 

Yokoshibu

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speed of light (299 792 458 m / s) / (164000000 freq) = (1.82800 meters) * (V factor of coax ??? example fig .89 % ) = (1.626922 meters) * (5/8 wave) = (1.01682 meters)

Those do not look like loading coils, I have seen them before with tinned copper straps on the inside or something similar.
 

kb2vxa

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Hi Uni and all,

The picture says nothing but some still are guessing they're some sort of 5/8 wave. My experience tells me they could be HF, VHF Lo or VHF Hi depending on what sort of "base load" coil they have. That can only be determined by reading the label, the frequency range is marked if the label hasn't fallen off. Once that has been determined you must use the frequency cutting chart supplied by the manufacturer, without the above information we're all clueless as you are. Then too like Yoko says they may not be coils at all which would make them 1/4 wave antennas. The long and short of it is we have no idea what we're looking at, I won't even venture a guess and come up looking stupid.

FYI, the chart always puts you spot on the money, no SWR measurement is need because the resonance curve usually puts the 2:1 points at over 4MHz from center.

Jhooten, whips and springs? OOOooo, KINKY!
 
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