Roof antennas

[lw8000]

Hello:
My current project is trying to wire up a 2-way GMRS radio in our coach. There's an antenna that is mounted on the roof just behind the front seats
which I thought was installed from the previous owner so I was looking for a way to hook to it or where it runs to inside the coach. Then it struck
me that maybe it is actually just the FM antenna but I can't recall if our GMCs have a whip antenna for FM, or if it was integrated to the frame. ?

Second question, if I need to install a new antenna, where are some good spots to put it so that I can run the wire in and up to the front of the
coach (radio is to be mounted under the front dash)? One idea was mounting to one of the mirrors and run the cable in. I'd prefer it on the roof and
out of the way, but each spot I've considered so far has its challenges on how to run the wire in and over to a wall and up to the front. I'm curious
what others have done for roof antennas.

Thanks in advance!
Chris
--
Chris S. -
77 Kingsley, 3.70 FD, mostly OEM -
S.E. Michigan

 

[Tom Lins]

> Hello:
> My current project is trying to wire up a 2-way GMRS radio in our coach. There's an antenna that is mounted on the roof just behind the front
> seats which I thought was installed from the previous owner so I was looking for a way to hook to it or where it runs to inside the coach. Then it
> struck me that maybe it is actually just the FM antenna but I can't recall if our GMCs have a whip antenna for FM, or if it was integrated to the
> frame. ?
>
> Second question, if I need to install a new antenna, where are some good spots to put it so that I can run the wire in and up to the front of the
> coach (radio is to be mounted under the front dash)? One idea was mounting to one of the mirrors and run the cable in. I'd prefer it on the roof
> and out of the way, but each spot I've considered so far has its challenges on how to run the wire in and over to a wall and up to the front. I'm
> curious what others have done for roof antennas.
>
> Thanks in advance!
> Chris

The antenna in the middle just behind the front cap is the factory AM-FM radio antenna. It runs up inside the center divider between the front
windshields.

--
Tom Lins
St Augustine, FL
77 GM Rear Twin, Dry Bath, 455, Aluminum Radiator Quad-Bag Suspension Solar Panel
Manuals on DVD
GMC Dealer Training Tapes
http://www.bdub.net/tomlins/

 

[Ken B]

For GMRS (I believe the frequency is around 465 mhz.) you want the antenna at the highest and clearest sideways view possible. Also you need to mount
in the metal portion of the roof and not the front or rear cap. The antenna requires a ground plane and that is what the metal roof up there does. I
have one ham radio antenna up there on mine and it is mounted behind the factory AM/FM antenna about 1/2 way between the front roof vent and the AM/FM
antenna. I forget what routing I used for the cable.

Speaking about cable DO NOT USE RG-58. USE something like RG-8X. RG-58 has way to much loss at the GMRS frequencies you will be running.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[lw8000]

Thank you guys! That helps tremendously. At least now I know I will need to put in a new antenna

Ken, Thank you for the mention on the cable. I was just starting to check on that and will do as you mentioned. Might as well be running the
correct cable since I'd prefer to only do this one time and be done with it.

I thought about putting the new antenna in the exact same location as you did, it is easy(ish) to get to. The only thing I haven't figured out is how
to route the cable as there are cross beams that look to be tight to the ceiling, however I see that there's a hole through them and there's also a
group of wires that run down the driver's side just behind the driver side window, so I'll probably try to follow those and see if it will work.

Take care,
Chris
--
Chris S. -
77 Kingsley, 3.70 FD, mostly OEM -
S.E. Michigan

 

[ghickey]

I am in the process of re-wiring the the entire coach and have pretty
much everything stripped out of the coach. I also need to run 3-4
antenna lines with NMO mounts. I will tell you it seems the best way
that I can see is to bring the coax to the channel that is right behind
the front headliner. There is plenty of room there to run the
coax--there is only a romex there that runs to the electrical outlet
behind the passenger seat underneath the dining table if you have one.
From there you run beside the passenger chair around to the dashboard.
I would probably run it behind the glove compartment to where you are
going to mount the radio.

Hope that helps.

--
Gerard Hickey / WTØF IRLP:3067/Echolink:529661
hickey DMR: 3102272
425-395-4554

> Thank you guys! That helps tremendously. At least now I know I will need to put in a new antenna
>
> Ken, Thank you for the mention on the cable. I was just starting to check on that and will do as you mentioned. Might as well be running the
> correct cable since I'd prefer to only do this one time and be done with it.
>
> I thought about putting the new antenna in the exact same location as you did, it is easy(ish) to get to. The only thing I haven't figured out is how
> to route the cable as there are cross beams that look to be tight to the ceiling, however I see that there's a hole through them and there's also a
> group of wires that run down the driver's side just behind the driver side window, so I'll probably try to follow those and see if it will work.
>
> Take care,
> Chris

 

[lw8000]

> I am in the process of re-wiring the the entire coach and have pretty
> much everything stripped out of the coach. I also need to run 3-4
> antenna lines with NMO mounts. I will tell you it seems the best way
> that I can see is to bring the coax to the channel that is right behind
> the front headliner. There is plenty of room there to run the
> coax--there is only a romex there that runs to the electrical outlet
> behind the passenger seat underneath the dining table if you have one.
> From there you run beside the passenger chair around to the dashboard.
> I would probably run it behind the glove compartment to where you are
> going to mount the radio.
>
> Hope that helps.
>
> --
> Gerard Hickey / WTØF IRLP:3067/Echolink:529661
> hickey DMR: 3102272
> 425-395-4554

Thank you Gerard, yes that does help! Per the other responses, I am thinking the exact same thing to run it inside that channel just behind the
headliner. I suspect the trick will be getting it over to the wall, but from there it seems straight forward. In this case my thought is to run it
down the driver's side instead of passenger, but to be determined soon
Thanks
Take care,
Chris

--
Chris S. -
77 Kingsley, 3.70 FD, mostly OEM -
S.E. Michigan