coil vibration, anyone else have this problem

[racetra]

I have 2 k40 bcmax antennas on my peterbilt. One day i noticed a howl sound and a bad vibration in the drivers door. Turns out it was the air flow causing the coil to vibrate. Any ideas on how to stop it.

 

[Beetle]

It's a natural vibration, so you'd need to change the airflow OR the mass of the antenna...it's only on the one side? (The other antenna is quiet?).

You could change speed, but ...

Check to be sure that everything is properly tightened. Figure out what's different about the airflow. Try getting a piece of shrink tubing just large enough to slip over the stinger and see if that is enough damping to silence things a bit. This is sort of like putting pieces of rope in yagi elements. That works for them; the shrink tubing might work for you.

 

[W5LZ]

Something else that might help is to tie a length of string/cord/ribbon to one turn of that coil. That will change the coil's 'shape' slightly so that air movement around/through that coil is different. That means the vibration caused by that air movement will change. It can also make it worse, so it's one of those try it till it's right thingys. Which turn to tie that thingy to? Beats me, that's just another variable you could try.
One thing to keep in mind is that the 'size', shape and weight/mass of that string (or whatever) will also affect the resulting resonant frequency (physical resonance) so if it get's wet, things change.
- 'Doc

 

[HomerBB]

Sometimes you can place a washer between the lower antenna shaft and the antenna mount so that the portion of the open coil that turns back into shafts are set front to back in the direction the vehicle is traveling resulting in less to no vibration from the coil.
Sometimes . . . It has worked for me.

 

[racetra]

I actually put a piece of Coca Cola box in the coil about 1/2 inch wide & 3 inchs long. I am not getting the antenna hot yet so not worried about any heat issues. Today i am gonna try to just turn it to same position as tbe other one