Multiple Antenna Question for 2M/70CM

[ccg_ga]

@mmckenna @prcguy

So I got the COMPACTenna installed today. The thick NMO mount and bracket all worked fine, but the coax cable isn't long enough to run all the way up through the dash and to the windshield where the scanner is mounted. I can leave it out and just pass it through the middle of the front seats and up to the scanner but I rather hide it back in the dash along with the coax for the other antennas.

What is the best approach here, I can buy the Larsen NMOHFTHK as just the mount, then a length of coax (like one of the Belden models) and build it myself but I wasn't sure how involved attaching the coax to the NMOHFTHK would be?

I also see Antenna Farm offers custom cable builds, but I didn't have the best experience with him on the last order for some of the scanner antenna install, unfortunately. Is there another shop either of you would recommend for a custom cable build?

 

[prcguy]

I would have used one of the NMO mounts that terminate in an N female or SMA female, then use a custom length of LMR-240 all the way to the dash area. SMA is nice because you can easily feed the cable with small SMA connector through the vehicle. If there is no connector on your NMO mount you could cut the stock cable very close to the mount and install a male and female SMA or BNC or anything, then run a new low loss cable to the dash area.

 

[mmckenna]

Yeah, I agree, roll your own...

https://www.theantennafarm.com/catalog/laird-technologies-vtpm800-1156

Or, depending on the style NMO mount you have, you can desolder the coax and run a longer length.

Or if you want to go really cheese-ball, just get an extension cable.

I'd get the Laird mount, and as prcguy said, get the length of LMR-240 you need to reach your scanner. Antenna Farm will make custom cables, so N male on one end, SMA male on the other.

Just be aware, LMR-240 is a bit stiffer than the RG-58 you ran for your other antennas. Not a huge problem, but can be a bit more of a challenge to install.
And make sure you waterproof the N connector at the antenna base.

 

[AK9R]

Steel belts in the tire. Steel frame around the rear window or steel roll bar in the back of the Jeep. I have to wonder how well that COMPACTenna will work.

 

[mmckenna]

Steel belts in the tire. Steel frame around the rear window or steel roll bar in the back of the Jeep. I have to wonder how well that COMPACTenna will work.

Post #90.

 

[ccg_ga]

Steel belts in the tire. Steel frame around the rear window or steel roll bar in the back of the Jeep. I have to wonder how well that COMPACTenna will work.

The tires are bias-ply, so they have no steel belting. Other than that, there are no other feasible places to mount it where it won’t get ripped off on the trail. It may not be optimal, but I think it will work fine for my needs. More details to come as I test it out...

 

[vagrant]

What about LMR-240-UF on his short run? It is much easier to work with vs. regular LMR-240. I ask because there may be something I am unaware of, besides the slight loss difference.

Just be aware, LMR-240 is a bit stiffer than the RG-58 you ran for your other antennas.

 

[ccg_ga]

I would have used one of the NMO mounts that terminate in an N female or SMA female, then use a custom length of LMR-240 all the way to the dash area. SMA is nice because you can easily feed the cable with small SMA connector through the vehicle. If there is no connector on your NMO mount you could cut the stock cable very close to the mount and install a male and female SMA or BNC or anything, then run a new low loss cable to the dash area.

Yeah, I agree, roll your own...

https://www.theantennafarm.com/catalog/laird-technologies-vtpm800-1156

Or, depending on the style NMO mount you have, you can desolder the coax and run a longer length.

Or if you want to go really cheese-ball, just get an extension cable.

I'd get the Laird mount, and as prcguy said, get the length of LMR-240 you need to reach your scanner. Antenna Farm will make custom cables, so N male on one end, SMA male on the other.

Just be aware, LMR-240 is a bit stiffer than the RG-58 you ran for your other antennas. Not a huge problem, but can be a bit more of a challenge to install.
And make sure you waterproof the N connector at the antenna base.

The mounting bracket is the Laird LBMB9034 which has a 3/4" mounting hole. If I use the VTPM800 will it still fit correctly on this mount since it is for a 5/8" mounting hole. I looked around a little bit for something comparable with a N connector and 3/4" mounting hole but haven't found anything yet.

On the LMR-240 - to @vagrant's question would it be fine to use the LMR-240-UF since it is more flexible? From looking on Antenna Farm either at LMR-240 or LMR-240-UF would one of the Belden cables be a good choice?

And on the connectors, I was thinking of using these 90-degree models:

N Connector - RFI RFN-1009-X-04
SMA Male - RFI RSA-3010-X

And last question - the coax stripper I have is the Terrawave HT-312B. Will it work for the LMR-240? This stripper is listed in the page with the RG58/RG59/RG8X/R6 models. I wasn't sure since the LMR-240 cable is listed as RG-8X as well.

 

[prcguy]

In the past when I had a 3/4" hole and 5/8" connector body, I wrapped one turn of 14ga solid copper wire around the connector body as a spacer. This will center the connector in the hole and the lock washer and nut should hide the wire.

I think LMR-240UF would be a good low loss cable choice for mobile use. I'm not up on the Belden versions.

The connectors look ok, I'm not familiar with your stripper and would probably manually strip the coax to spec if I didn't already have a Times CST-240A tool.

The mounting bracket is the Laird LBMB9034 which has a 3/4" mounting hole. If I use the VTPM800 will it still fit correctly on this mount since it is for a 5/8" mounting hole. I looked around a little bit for something comparable with a N connector and 3/4" mounting hole but haven't found anything yet.

On the LMR-240 - to @vagrant's question would it be fine to use the LMR-240-UF since it is more flexible? From looking on Antenna Farm either at LMR-240 or LMR-240-UF would one of the Belden cables be a good choice?

And on the connectors, I was thinking of using these 90-degree models:

N Connector - RFI RFN-1009-X-04
SMA Male - RFI RSA-3010-X

And last question - the coax stripper I have is the Terrawave HT-312B. Will it work for the LMR-240? This stripper is listed in the page with the RG58/RG59/RG8X/R6 models. I wasn't sure since the LMR-240 cable is listed as RG-8X as well.

 

[mmckenna]

On the LMR-240 - to @vagrant's question would it be fine to use the LMR-240-UF since it is more flexible? From looking on Antenna Farm either at LMR-240 or LMR-240-UF would one of the Belden cables be a good choice?

Either one would be fine. I've run LMR-240 in vehicles before, and it wasn't impossible, but I wasn't running it through any hinged points like a tailgate or spare tire support. The UF might be a better choice since it'll stand up to flexing better. And, RG-58 would still work fine, just won't perform quite as well as the 240.

And on the connectors, I was thinking of using these 90-degree models:

N Connector - RFI RFN-1009-X-04
SMA Male - RFI RSA-3010-X

I've used RFI connectors before and never had an issue with them. Never used the 90º models, but I don't think they'd be any different.

And last question - the coax stripper I have is the Terrawave HT-312B. Will it work for the LMR-240? This stripper is listed in the page with the RG58/RG59/RG8X/R6 models. I wasn't sure since the LMR-240 cable is listed as RG-8X as well.

I have a similar one. LMR-240 is close enough to the same size at RG-8X so I think it'll be fine. The strippers don't do a perfect job, and I keep a small X-acto knife in the kit with mine for cleaning things up.

 

[ccg_ga]

@mmckenna @prcguy

Thanks gents. Here is what I wound up with/ordered:

Coax Cable - Times Microwave LMR-240UF - 30 feet
N Connector - Times Microwave TC-240-NMH-RA-D N-Male Right Angle
SMA Connector - Times Microwave TC-240-SM-RA-SS-X SMA Male Right Angle

I ordered the cable with the N-connector attached from Antenna Farm. I'll cut the coax and add the SMA connector once I get it ran up to the scanner.. and put the marine heat shrink on both ends as well.

On the mount, I did some more Googling and would up at Arcadian and their product page for the VTPM800 states that it is 3/4" NMO to 5/8" N-Female - so either that is perfect and it will fit the 3/4" bracket mounting hole as-is or I will give the 14ga solid wire a try as @prcguy suggested. I know this may be just stating that the NMO connector itself is 3/4" so we'll see how it fits.

One cool thing about Arcadian - their site said the mount was out of stock so I chatted with one of the customer service reps and they told me they could "spare 1 from their reserve stock" and already processed the order.

@vagrant Thanks for the LMR-240UF suggestion as well!

 

[mmckenna]

N and UHF connectors are 5/8 x 24 thread size.

If it's 5/8" diameter at the mount, the 14ga wire is a good solution. It'll only be 1/16 off all around, and some careful install will probably reveal this isn't a big issue.

 

[prcguy]

14ga is about .064 dia and there is 1/8" to make up, so a full circumference of .064 wire around the connector body is right about .128" and there is also a little slop in the 3/4" hole.

N and UHF connectors are 5/8 x 24 thread size.

If it's 5/8" diameter at the mount, the 14ga wire is a good solution. It'll only be 1/16 off all around, and some careful install will probably reveal this isn't a big issue.

 

[cmdrwill]

Like this..

 

[vanhalo]

This is what I came up with for my JKU.

 

[ccg_ga]

This is what I came up with for my JKU.

Nice, I like that foldable mount. I run the soft top in the summer and a hardtop in the winter.

If I had the hardtop on full time I would set it up similar to yours. Solar power also!

 

[vanhalo]

Nice, I like that foldable mount. I run the soft top in the summer and a hardtop in the winter.

If I had the hardtop on full time I would set it up similar to yours. Solar power also!

It wont fit in my garage if I take the spare tire off. A folding antenna mount was a must.

 

[krokus]

This is what I came up with for my JKU.

How well does the antenna work without a (proper) ground plane?

 

[vanhalo]

How well does the antenna work without a (proper) ground plane?

I do not appear to have any issues with reception.
I am running an SDS-200 scanner.

 

[ccg_ga]

The LMR-240UF showed up today. I think it will route just fine, doesn't seem too stiff to me.

The NMO mount is the last thing I am waiting on, and it should be here on Tuesday. Planning on getting it all swapped out over the upcoming week and doing some testing.