If I possessed the talent to cut a clean hole into a vehicle and run the coax neatly, you bet your back side that my vehicles would have Larsen NMO 30's with the appropriate mast size. But I don't, so magnet mounts rule the day.
On the other hand, keep your eyes open, and you may run across someone local to you that would be happy to assist. Many ham operators have the right tools. 3/4" hole saw, coax crimpers and a simple antenna analyzer isn't uncommon.
If I possessed the talent to cut a clean hole into a vehicle and run the coax neatly, you bet your back side that my vehicles would have Larsen NMO 30's with the appropriate mast size. But I don't, so magnet mounts rule the day.
Greenlee knockouts are better than hole saws.
Greenlee knockouts are better than hole saws.
I have a 3/4" knock out punch, and it's been handy on a few occasions.
But as prcguy said, it can take longer to do the work since you need access to both sides of the sheet metal. Not always possible on a mobile install.
The DeWalt brand 3/4" hole saw designed for steel works really well. Got in a pinch once and left my hole saw in the office. A quick trip by Home Depot got me what I needed and finished the job just fine.
The step bits (aka Christmas Tree bits) are sketchy. They can grab if you are not careful. Not something an inexperienced person should be trying. The nice benefit to the true NMO hole saws is that they have a depth limitation design, so no risk of going to deep and damaging the headliner.
A longer whip would have to be trimmed to the same length as a stock whip so I don’t see any advantage unless the new whip is thicker. If you get a higher freq coil like 30 or 34MHz as mentioned in post 52 then you can make use of a longer whip and improve efficiency.Just looking at this thread again. Has anyone tried the longer (W640) whip with the NMO27? Based on the comments with cut charts, it sounds like it would be much too long, and have to be trimmed to the point of the shorter whip.
Is there a recommended spring that can be used with the Larson NMO30 and the 64" whip?
@mmckenna assuming I use my soon to arrive nanoVNA to properly tune the system, is there a downside to having the spring in the system?