coils on mobile antennas

[JesseJamesDallas]

I use a tone generator App I downloaded on my Smartphone, and a 4' florescent light bulb...

Duck tape the Mic's PTT button down, then set the tone generator...Then I stick the light bulb up to the antenna to make it light-up, and start walking around the truck and where ever the bulb go's out, I place a Playing Card on the ground...

Then re-adjust the antenna, and do it all over again!.......Trick is holding the light bulb at the same height while walking...