Where's The Coax???

[mlevin]

The other day I noticed that my mom's Chevy Express had an NMO mount on it. My question is where/how do I get to the coax to hook up my antenna? Or is there no coax installed at all? If there's no coax, then how would I go about accessing the NMO mount to hook something up, while doing minimal damage? It's notmy car so I don't want to do anything to out there :wink:

 

[nmfire10]

Well, I find it unlikely that there is a mount with no cable. Look around under the dash or center console. Pull up the carpet, etc. It is around somewhere.

 

[INDY72]

Umm they sell a few mounts that you do it yourself with cable.. its tricky,.. you better be good with crimping/soldering to do your own attach... if that mount has no cable already that is,.... is this a permanent mount? Look in the trunk and see where the base lead is,.. and youll know soon if there is one attached or if it got cut off.... if its still attached,.. follow it,... the other end is the key lol,.. if its cut then youll have to get an bnc and crimp/solder it on.... or you may get lucky and it has an plug you can get an adapter for... best of luck. BTW,.. what kind of ant is on the mount?

 

[mlevin]

Nothing is on the mount. I want to put my 800 mobile on it. It fit's just don't know where the coax is. Also, there's no trunk. This a twelve seater passenger van. The other day I noticed that my mom's car had a permanent NMO mount installed, and I would like to take advantage of it if possible. I have no idea why it has the mount. She bought it used, and before she bought it, it was part of a rental fleet.

Okay, so pardon my ingnorance, but what's a base lead, and what does it look like?

 

[nmfire10]

There is a piece of coax going from that NMO mount to somewhere. Again, it is probably under the dash, shoved under a carpet, or under a seat. It is around somewhere. No idiot would put in a mount but not install the coax that goes with it, Very often, the coax is an integral part of the mount to begin with. It is there somewhere, you just have to look.

 

[mlevin]

Okay, thanks for the info. I'll start looking around and let you know what I find.

 

[mlevin]

I found it!!!! A whole bunch of what looks to be RG58 right underneath the steering column. It does have a connecter but not a BNC. I don't know what it's called, but it looks like the same kind of connecter that goes from the VCR to the TV. I'm sure you know what I'm talking about. Now all I have to do is somehow hook up a BNC connecter. Thanks for all the help

 

[mr_hankey]

are you sure that's not the "black box" interface?

: )

 

[mlevin]

I don't think so, it's not hooked up to anything, just rolled up, tied together, and tucked away under there. I didn't have time to get such a good look, but the cable did say Antennex on it. When I have some more time, I'll do some further investigation.

 

[unitcharlie]

with apologies...

pull some of the cable out to see if you can find a number.... if it has an "f" or "n" connector on it it might be 75 ohm stuff.... if it isn't 75 and is compatible with the scanner then you can go to rat shgack and buy an adapter for about 2.50....

 

[nmfire10]

I don't know of any mobile radio stuff that uses F connectors or 75 ohm coax. Unless they have that plugged into a little TV, there would be no reason for that. Plus, I've never seen an NMO mount that used RG-59 or RG-6 which is what it would have to be for 75 Ohm.

My guess is it is normal RG-58 coax. Are you SURE the connector is an F connector like for a TV? It might be a "Mini-UHF" which is a small version of the PL-259. Lots of Motorola mobile radios use Mini-UHF connectors for the antenna.

Either way, you should use that for your scanner. Get an NMO scanner antenna, cut the cable to the proper length, and put the proper connector on the end. It will work 10x better than any Mag mount POS.

 

[mlevin]

Well I'm pretty sure it's RG58, so it must be a UHF-mini. Both F connecter, and the UHF-mini, do look similar. When I have some more time to take a thorough look, I'll pull some out to see for sure.

 

[mlevin]

Okay, after further investigation I've confirmed that the cable is RG58/U and that it has what appears to be a mini-UHF connecter on it. Now my next question is how would I get a BNC connecter on. Is there some sort of adapter I can buy, that would screw right on? (I'm useless with a soldering iron)

 

[ECPD279]

Mo, you'll need to figure out if it's a Mini-UHF or a TNC.....they look very similar. If it's TNC, Radio Shack will have the following:

TNC to BNC Part# 278-144 $5.29 in store

Unfortunately it is more likely Mini-UHF in which case you'll either have to string three RS adapters together (Mega Loss) or look elsewhere.

If it was me, I'd just go to RS and buy a crimp on BNC, cut the Mini-UHF off and throw a BNC on there. That'd give you the best signal. Good Luck Mo!!

 

[nmfire10]

If this is for a scanner, cut off the Mini-UHF and get the BNC connector that doesn't require soldering. Putting a stack of adaptors on it will just make a ton of loss.

 

[INDY72]

Yepper if your mom has no issues,... cut the connecter off,.. do the proper foldback with the outer shield, make sure you have the middle wire extended the right length and crimp on a BNC! At least that'll fix up the one on your mom's car... but for the van,... If you do not wish to have holes drilled get a mag mount for it.... and if you have the cash flow for it get a NMO mag mount,... that way you can play around a lot easier with the ant whip elements.For suggestions on running the cable on the van,.. try this... run it tight to the driver's door,.. run the cable under the weather seal so it is not only protected,.. but also prevents water from leaking into your van. Then once its all the way to the "step on plate" , run it under your seat,... or under the floormat to where your installing your scanner. This is how mine is mounted in our van.

 

[Halfpint]

Uhmmm, milf...,

I `think* that `mom's car' *is* a `van' and I'd suspect that the mount was for some company's `system' radio or possibly `data system'. (I worked with an outfit that serviced a `RF Modem to GPS' system for the `gummit' and we mainly used cellphones for comms out of the `field' and a few RELM HTs between ourselves in the `field'. Our `test rig' was hooked up to a roof mount and had a proprietary connector on the co-ax for hookup. (When I asked why not just use a magmount so that we didn't have to always be setting up every time we went out the explanation was that the *location* of the antenna was `critical' for the measurements and us `field agents' couldn't be depended upon to set the antenna correctly all the time. [What was really funny was we'd done exactly what I suggested when we had to go out and all three of the vans were in the shop for repairs, which was about 50% of the time, and no one had `carped' about our measurements being `off'! I'd also carried along at least a couple scanners with magmounts *and* even brought along another magmount for use with one of the HTs for when my partner was just outside the range of the HT's rubberducky! {SNICKER!} BTW, just before the `project' finished they went and bought three more vans to augment the other three! Some `bean counter' someplace decided that it would be cheaper than all the renting we'd been doing *and* they used magmounts on them instead of the NMOs! {CHORTLE!}] ) Just a `thought?

mlevin,

Sounds like `luck' is on your side! If the `extra' co-ax isn't *excessively*, IE: Only 6' - 8', long and you cannot use just one adapter *I* wouldn't do more than just remove and replace the connector. There just *may* come a time when that little bit extra will come in handy. Coiling it back up under the dash *isn't* going to affect things all that much and it can be surprising as to how much co-ax it can take to reach even the middle seats and keep it out of the front seat's way. (It may seem that it may not be something you might be planning on but, according to his wife, Edsal Murphy was an optimist. {VBSE GRIN!})

Just an `Olde Fart's' 2¢ worth. {GRIN!}

 

[mlevin]

I would love to cut off the connecter and crimp on a BNC, one problem. I tried doing that once before on another project and almost pulled my hair out :? . If someone doesn't mind giving me a brief tutorial on how to use it then I'll give it a shot. The instructions on the back of the package where less then helpfull.

Milf, BTW my mom's car is the van. You need to have a big van when you have five kids and carpool another five kids. As for my mom minding me doing anything. Her words where "Do whatever you please, just don't screw up the car "

 

[INDY72]

OK as requested by Mo in chat.... Here is a basic crimping lesson:

One, cut off old connector.
Two, cut off outer shield for working space.
Three... fold back the inner braided wire so that it has contact with the outer edge of your connector.
Four, cut away the inner shielding around the inner wire so that you can insert it.
Five, insert your coax into the BNC connector.
Six, Make sure the inner wire is "seated" in the tip slot.
Seven, Take your crimping tool, or pliers, and "crimp" by squeezing the base of the connector down tightly.
You should then be good to go.

 

[mlevin]

Okay now what? I went to RS and got a crimp on BNC, went home and got to work. The problem is that when I pulled out the cable, it turns out there are two different cables. One is RG58A/U, and one is RG58/U. Which one do I use. I think the A/U is for a TV and I should use the /U. Also the /U says 50 ohms on it, so I'm pretty sure that's what I want to use, but I want to make sure before I cut anything.

PS, The RG58/U is much longer then the other cable, so I think I want to use this one.