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Premium Subscriber
Jun 21, 2007
Toronto, ON, Canada
This has been an ongoing issue..

I've got 4 scanners mounted in my Hyundai Santa Fe -- 3 of them are Uniden BCT15's and 1 of them is a BCD996T. The 996 is used for VHF, and the BCT15's are all for 800 Mhz systems.

The antennas are Larsen mag mounts; the model for the 800 Mhz antennas is SPEC800. They are chrome, tuned antennas. They sit on the back of the SUV near the hatch. The problem is the signal that I am getting.. I'll be side by side somebody else with almost the same setup (except with antennas that are permanently mounted) and they'll have a signal and I won't. Everybody seems to have a different opinion about what the problem could be.. and others say it is because they are Uniden's and not Motorola's (but others who have Uniden's aren't having these problems). I've been told all sorts of things could be the problem...interference, intermod, ground plane, mag mount, etc. I'm getting frustrated with the setup and am not sure where to turn. Any advice?


Feb 6, 2007
4 radios... and how many antennas?

Everybody knows that mag mounts aren't as effective as permanent mounts. The issue is the counterpoise, or the ground plane, for the whip. The mag mount capacitively couples to ground (maybe), where the permanent antenna mount digs into the metal on the backside of the mounting hole and at least makes a half-hearted effort to make an electrical connection.

The importance of the ground plane is one of feedline radiation or, in the case of a receiver, feedline pickup. You don't want the coax to be acting as part of the antenna. This is part of the problem with mag mounts, and why, at best, they never seem to measure up to permanent antennas.

There may be something else wrong, too. Want to make it better? Drill holes.
Apr 7, 2008
Yes, drilling holes makes all the difference! Well, I guess I never tried a mag mount, I just went straight to drilling holes. I drive a 12 year old Honda Accord though, so I was perfectly willing to turn my trunk lid into swiss cheese. ;)

At the very least, you could get some of those nifty Comet adjustable trunk/hatch lip mounts, I believe those have screws that dig into the metal on the inside of the lip (I could be wrong, in fact I often am!) I think they even make a luggage rack mount if that's your style, don't know if your luggage rack needs to be electrically bonded to the car body for that to work though (I would think it does.)
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