Multiple mobile antenna question

[Sacramento_Bill]

Hello, I am a little confused and would appreciate some enlightenment.

I have a F150 that I want to mount a dual band 2m 440 antenna and a wide band scanner antenna on. Is there a rule on how close they can be together? Can I put them both near the middle say a foot apart?

Secondly can I run the coax side by side to the two radios in front or will that cause interference issues when I transmit?

Thank you for your wise advice.

 

[popnokick]

At least a foot apart, but every inch farther apart the better. The farther apart the less chance of inflicting damage to the scanner when transmitting. I've never damaged my scanner by transmitting with my 2M/70cm dual bander in multiple mobile setups and antenna placements... but never closer than 12 inches in any of them. And yes if you can... run the antenna coax to each antenna along a different path. Don't tie them to each other. HOWEVER - You are still going to get interference on the scanner when you transmit. If it's severe, it will go right in the front end of the receiver and appear on nearly every frequency. If not so severe.... which is what you are trying for... it may only appear on certain scanner channels. And even if you don't hear your own transmission on the scanner, you could still be desensing the scanner. It's a fact of operating a scanner near a transmitter in the same vehicle... I just turn my scanner down when I transmit... haven't damaged a scanner yet. Currently, my antennas are about 3 feet apart.

 

[mmckenna]

What cab model is the F150?

I've got a 2011 F150 crew cab with two antennas on the roof, one 1/4 wave VHF whip and one 1/4 wave 800MHz whip. Both are transceivers, and I have no issues with the two interfering with each other. The two antennas are probably 20 inches apart. Both are on the center line of the cab on the left/right plane.

RF decks are behind the rear seat with remote heads under the dash. Coax cables are run up either side of the "C" pillars, however they do run side by side down the center of cab coming from the antennas to the rear. Both are double shield RG-58 with NMO's.

I agree with Poponokick, get the antennas as far apart as you can. I've heard a lot of different measurements, 12 inches is probably the minimum I'd go with. I try to do at least 1/4 wavelength, more if I can.

I did have one instance on my dad's Chevy Colorado a few years ago where we had a 2 meter VHF and UHF (GMRS/70cm) antenna about 12 inches apart. The UHF radio was a commercial 35 watt radio. The VHF radio was a Yeasu amateur radio. It appeared that the RF from the 35 watt commercial UHF radio wiped out the diodes on the front end of the Yeasu hammy radio. The Yeasu went completely deaf and had to go back for repair. UHF Icom never had any issues from the 60 watt VHF.