Amateur Mobile Antenna Questions

[yaknamedjak]

Also, should have mentioned this photo is from the street/port side angled towards the rear of the Expedition.


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[yaknamedjak]

So measured the NMO distances that are currently on the roof. Still haven't taken the truck over to get the roof done, but also still waiting on my console from Troy which has taken like 5 weeks now. Should get the roof done first week of February. Could anyone comment on best arrangement and if everything will be far enough apart?


Also would like to put another nmo opposite of 4 on the other side for the other 4g, so they're symmetrical. And then need a recommendation on GPS placement. Was thinking forward of 1 in the center.

1 to 2 -18"
2 to 3 - 14"
1 to 4 - 15"
3 to back of roof -26"

Thanks


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[yaknamedjak]

That's pretty common practice around here. Reality is that most departments do not need 100 watt radios. Even CalFire here in California, who does wildfire suppression has switched to 50 watt radios as their standard.

The PD I look after had to have 100 watt radios (if 50 watts is good, 100 must be better, right?). I had the shop that did the installation turn them all down to about 80 watts. The radios will thank you for this.







The Motorola equipment should have pretty good filtering on the front ends, so you should be OK with those with some reasonable spacing. I've always done at least 1/4 wavelength on the lowest frequency, but that has always been with 50 watt radios. I've heard people say 1/2 wavelength, which would be better if you have the space.



The scanner is the one you should be concerned about. They have very wide front ends with little filtering. Pretty easy for those to get popped by a 100 watt VHF or UHF radio.



GPS antennas will probably be OK either way. Many manufacturers sell antenna mounts with the GPS and NMO base on the same mount.



Physical location would depend on the existing hole locations. Photos would be helpful.



Other thing to consider is feed line losses. Since higher frequencies suffer more from feed line losses, you might want to have your UHF radio be the shortest cable run followed by the VHF, then the scanner. The GPS shouldn't matter since most of them have some sort of amplification built into the antenna module.

Any thoughts?


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