cutting antenna
- Thread starter jakegday
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jonny290
Member
B, but there's likely a loading coil between B and C so it's not just a simple quarter wave calculation.
You cut the whip itself, usually from the bottom, and while it's removed from the rest of the assembly, so it works out to "B", like jonny said. This is what most manufacturers show in their cutting charts, which I presume you don't have.
yes, that is a loading coil, im not sure what you mean by the "simple quarter wave calculation" i bought the antenna and loading coil together, and the mount was a separate piece, the website i got it from has a cutting chart for my specific antenna/coil, but since its gotta be down to the exact 1/4 inch, i wanted to be sure i was measuring it correctily
so B it is....
so B it is....
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Bill_White
Member
What radio are you using this antenna with??
If it's a transmitter, measure the SWR.
Take a reading at the top and bottom of the band you want to use the antenna for and make a note of it. If the SWR is low at the bottom of the band AND high at the top end of the band, the whip is too long. AND, yes you guessed it...
If the SWR is high at the bottom of the band and low at the top end of the band, the whip is too short.
If it's a transmitter, measure the SWR.
Take a reading at the top and bottom of the band you want to use the antenna for and make a note of it. If the SWR is low at the bottom of the band AND high at the top end of the band, the whip is too long. AND, yes you guessed it...
If the SWR is high at the bottom of the band and low at the top end of the band, the whip is too short.
jim202
Member
Being the old timer radio grunt that has had to replace untold antenna coils that have
been ripped from the roof of vehicles over the years, I tend to remove the top of the
whip. I have come to do this for a number of reasons. The first is to get rid of the
small round ball that is at the top of all new whips. This just adds to the damage
the whip gets when it hits a tree branch. The more weight, the further the tip bends
when it strikes an object. Second and foremost, the ball has a bad habit of getting
caught in the branches and won't let go. When this happens, you can actually rip
the mount out of the roof if the coil doesn't break first.
Use to see body shop repair bills that were rather high to repair torn roofs on cement
mixers. I started using a different style of antenna coil and whip and no more roof
repairs. Just replace the whip and coil and keep on trucking. Repair cost was about
$60 on the average instead of around $600 for the roof repair, plus a new antenna
system.
Do what you want and use the parts you want. Just thought I would let you know how
I fared over the years.
By the way, I use the measure points from the top of the whip to the bottom flat point where
the mounting stud screws into the top of the coil.
Jim
been ripped from the roof of vehicles over the years, I tend to remove the top of the
whip. I have come to do this for a number of reasons. The first is to get rid of the
small round ball that is at the top of all new whips. This just adds to the damage
the whip gets when it hits a tree branch. The more weight, the further the tip bends
when it strikes an object. Second and foremost, the ball has a bad habit of getting
caught in the branches and won't let go. When this happens, you can actually rip
the mount out of the roof if the coil doesn't break first.
Use to see body shop repair bills that were rather high to repair torn roofs on cement
mixers. I started using a different style of antenna coil and whip and no more roof
repairs. Just replace the whip and coil and keep on trucking. Repair cost was about
$60 on the average instead of around $600 for the roof repair, plus a new antenna
system.
Do what you want and use the parts you want. Just thought I would let you know how
I fared over the years.
By the way, I use the measure points from the top of the whip to the bottom flat point where
the mounting stud screws into the top of the coil.
Jim
jakegday said:when you cut an antenna, you measure it from the top down to the..... A, B, or C??
thanks!
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im using it with a scanner, a pro 83 to be exact, no transmitting, although it doesnt pick up the 42mhz range as well as i'd like, it does it way better then it did before, i dont know if i need an even better antenna, or just a better scanner to pick it up perfectly
i just thought of another question maybe someone could help me with.... when the antenna is on the roof of my car it works great, then when i take it off and bring it inside, it doesnt work so well, im assuming this has to do with it being grounded, so can someone give me a suggestion as to how i can ground it inside my house??
jhooten
Member
Take the whip off and cut it to the length in the cutting chart.
Inside stick the magnet on the largest metal object available like the fridge.
Inside stick the magnet on the largest metal object available like the fridge.
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