Whip Antenna Length

[RadioDitch]

I'm actually embarrassed that I have to ask this, but it's been that long since I've cut a whip antenna, and I've forgotten.

When I'm cutting a 5/8th wave mobile whip, do I also have to account for the length of the space between the contact pin, and the bottom of the insert space for the whip?

Thanks guys. CRS syndrome setting in...

 

[jim202]

I'm actually embarrassed that I have to ask this, but it's been that long since I've cut a whip antenna, and I've forgotten.

When I'm cutting a 5/8th wave mobile whip, do I also have to account for the length of the space between the contact pin, and the bottom of the insert space for the whip?

Thanks guys. CRS syndrome setting in...

Normally the antennas come with a cutting chart that should get you close. The chart should point out where the measurement was made from.

Then use an SWR meter to bring down the reflected power as low as you can go. If you make a measurement at the highest channel and then at the lowest channel, take notes. The lower SWR should indicate which frequency is the direction to go. The lower SWR points you in that direction. If the lower reading is on the higher channel, that indicates the antenna is too long. If the lower reading is on the lower channel, that generally indicates that the antenna is too short.

If the whip needs to be cut, I would only take off about 1/4 of an inch each time. Make sure the rod is pushed all the way down into the coil. You should have maybe 1/4 to 1/2 inch to play with on the depth of the hole the antenna rod goes into.

 

[cmdrwill]

I'm actually embarrassed that I have to ask this, but it's been that long since I've cut a whip antenna, and I've forgotten.

When I'm cutting a 5/8th wave mobile whip, do I also have to account for the length of the space between the contact pin, and the bottom of the insert space for the whip?

Thanks guys. CRS syndrome setting in...

That depends on the manufactures cutting chart. A "5/8 wave base load" antenna would be affected by the transformer/loading coil.

If at all possible use the manufactures cutting chart, and cut a little off at a time.