Larid anttenta Laird 144-174 MHz 3 dBi 5/8 Wave Base Loaded

bmendez

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Hi I have a larid anttenta I it tells me I have to tune it to what the frequencies which is 155.4450 but on my cutting chart they don’t listed so should I cut it to 40 for 156mhz or should I cut it for 154mhz
 

mmckenna

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Hi I have a larid anttenta I it tells me I have to tune it to what the frequencies which is 155.4450 but on my cutting chart they don’t listed so should I cut it to 40 for 156mhz or should I cut it for 154mhz
If the cut chart has a measurement for 156, then use that. It's close enough. The 5/8 wave antennas have a few MHz of useable bandwidth that will provide acceptable SWR.

Ultimately the cut charts will get you close, but it's still a good idea to follow up with an SWR meter if you are going to use this for transmitting.
 

bmendez

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Right now I have the anttenta cut for 154.00mhz which is 42inch would that affect the 155.MHz freq
 

prcguy

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The only way to tell is to do what has been mentioned, check it with an SWR meter or antenna analyzer. The cutting chart is approximate and your same antenna mounted on a van roof or sub compact trunk lid will give slightly different resonant points when cut to 42in. At least you cut it erroring on the slightly longer side, which is a good idea. Borrow or steal an antenna analyzer and dial it in perfect for your frequency, then enjoy it.

Right now I have the anttenta cut for 154.00mhz which is 42inch would that affect the 155.MHz freq
 

kayn1n32008

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The cutting chart should be a linear scale. Take the length for 156, subtract it from the length for 154, divide by two and subtract the resultant number from the 154MHz length. That will be your length for 155Mhz. If it’s for receive only, that will work just fine.

if you are using the antenna for transmit, start at the 154MHz length, and trim 1/4” at a time until you get a 1.1:1 or 1.2:1 VSWR match.
 
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