Types of antenna mounts?

[Miescha]

For vhf/uhf I only own the Larsen NMO mounts. I'm not opposed to others, I just have limited experience.

For HF, I only own the 3/8 x 24 stud mount ham sticks (typical CB antenna mount I guess). Again, only due to lack of experience.

My understanding is that there are only two types of mounts for vhf/uhf antennas: The NMO and the UHF (which apparently goes by various other names including the PO, but I'm not sure on this). Among NMO mounts, there is also some variation among manufacturers such that a Larsen NMO coil may not mount properly on a Diamond NMO bracket.

For HF antennas, there are the same two options as above plus the standard CB type ham stick mount (the 3/8" x 24 stud).

Is this correct? What am I missing? I know I've seen 80s with dual antennas mounted on the front ARB bull bar (despite the ground plane issues). And I know these are commonly one HF (usually 11m CB in the states) and one VHF/UHF.

Here is the problem I ran into today when trying to order from HRO. The holes in the ARB front bumper (top mounting tabs) are 3/8" and work fine for the common 11m CB type ham stick antenna. But I'm told there no vhf/uhf antenna that will mount on this tab without enlarging the hole.

So is this correct? If I enlarge the hole, all I can think to use is a 3/4" drill bit and that will put the vehicle side of the hole pretty darn close to the edge of the tab. Also, enlarging the hole will make mounting aux lights in that position more difficult if I decided to do so in the future.

I don't have room on the roof for the optimal drilled hole NMO mount, so I guess the only other option is to ignore the bull bar and just use a hood groove mounting tab and the Larsen NMO I already have.

Thoughts?

 

[wesintl]

It was a pita to drill out the antenna brackets on the arb bar. I decided against it and would make an adapter bracket. Then I was at the local HRO and bought this. $10

Dodge Ram Fender Mount - Vehicle Specific Antenna Mounts

I bolted it to the arb bar tab and used the nmo on the other side. I did open the nmo hole just a tad to get the though the opposite way rather then feeding the wire though. I could probably take a pic tomorrow if you really needed it.

You could also use an trunk style mount on the side of the hood.

HTH

 

[Miescha]

Damn, I was really hoping to mount up an antenna on those tabs. I guess I'll still use one for the HF until I switch over to an NMO style HF antenna.

I guess I'll just go with the hood groove bracket - probably just fab up something myself for now.

 

[Miescha]

I did find this comet ad-25m adapter that allows conversion from SO-239 to NMO. I don't know what size hole is used for SO-239, but it sure looks like the kinds of thing that would allow a 3/8" hole to be used for an NMO mount.

 

[Kofoed]

I would double check on that 3/8" measurement for the standard UHF connector (as opposed to the mini UHF connectors) THe standard UHF connector OD is the same one on the back of the radio.

 

[stu050]

For vhf/uhf I only own the Larsen NMO mounts. I'm not opposed to others, I just have limited experience.

For HF, I only own the 3/8 x 24 stud mount ham sticks (typical CB antenna mount I guess). Again, only due to lack of experience.

For HF antennas, there are the same two options as above plus the standard CB type ham stick mount (the 3/8" x 24 stud).

Is this correct? What am I missing? I know I've seen 80s with dual antennas mounted on the front ARB bull bar (despite the ground plane issues). And I know these are commonly one HF (usually 11m CB in the states) and one VHF/UHF.

Here is the problem I ran into today when trying to order from HRO. The holes in the ARB front bumper (top mounting tabs) are 3/8" and work fine for the common 11m CB type ham stick antenna. But I'm told there no vhf/uhf antenna that will mount on this tab without enlarging the hole.

So is this correct? If I enlarge the hole, all I can think to use is a 3/4" drill bit and that will put the vehicle side of the hole pretty darn close to the edge of the tab. Also, enlarging the hole will make mounting aux lights in that position more difficult if I decided to do so in the future.



Thoughts?

It is no problem to enlarge the holes in the ARB bar to the size you require. The mount is designed to support the HF autotune antennas that we have here in Australia. These are typically 2.4 metres long and weigh 5-6 KG.

This is the spec sheet for the Codan 9350 HF autotune antenna.

http://www.codan.com.au/Portals/0/publications/hfradio/9350whip_data.pdf

Failing that, quite a few people here weld additional mounting brackets on to their bar to suit their specific needs. Eg, lights satphone microwave antennas etc.


Here is a pic of my HZJ105 with Codan 9350 HF antenna on bullbar.

 

[JMZ-]

where can I purchase the Larsen NMO mount. I want to buy a Larsen 2/70B and mount it on my 80's hood. Could not figure it out on universal-radio.com

Thanks.

 

[rusty_tlc]

The Damond K400SNMO hatch mount works well on the 60, 80 and 100 series. It is also available in the So-239 version (for use with PL-259 base antennas)
It can be mounted on the hatch, trunk or hood.

BTW Universal and HRO have higher prices than Ham City.


Miescha, trick tabs are a better option than the flat tabs used for lights. A shop would only charge a few bucks to weld one on for you.

 

[JMZ-]

thanks, Rusty_tlc.

will the K400 mount attach on the margin of the hood, or attach on the fender?

Seems like Ham City does not carry Larsen antenna.

THX.

 

[Miescha]

Ham City doesn't show anything under Larsen.

Gigaparts.com has the Larsen NMO 2/70 BK (its the kit with everything you need), but the price is $110 and that seems high (and gigaparts is generally pretty competitive IME).

I ordered my stuff from HRO as part of a much larger order that was, overall, very competitive (including my Icom IC-7000).

HRO does have it, but you'll need to order the NMO 2/70 B (assuming you want it in black). This includes the coil and whip only and the costs is $54 ($70 if you want the chrome).

Then you'll need to add the Larsen NMO-K coax kit for $13 for a total of $67 which is a damn site better than $110 from gigaparts.

Of course, if you don't trust your soldering skills with the PL-259 connector, you can order the Larsen NMO-K with FME termination for $16 and then just buy the Larsen FP which is the FME to PL-259 adapter for $4.20.

As for mounts, I think Rusty-TLC gives good advice. I've only used the Larsen hood-groove mounts which are pretty simple 'L' brackets. Otherwise, I use the mounting tabs on the ARB front bumper.

Good Luck.

 

[Miescha]

For vhf/uhf I only own the Larsen NMO mounts. I'm not opposed to others, I just have limited experience.

Well, things change quickly. I placed another order about two weeks ago and received the following antennas:

1. Diamond NR 770 HNMO (3.0/5.5 dBi gain ; 200w PEP ; 38.2" height ; 1/2 wave on 2m and 2 5/8 wave on 70cm) This is planned for poor ground plane applications such as the bull bar
2. Diamond SG 7500 NMO ((3.5/6.0 dBi gain ; 150w PEP; 41" height ; 1/2 wave on 2m and 2 5/8 wave on 70cm) Same application as above
3. Larsen NMO 27 (for the 11m CB band)
4. Larsen NMO 2/70 SH (this is the shorter, more stout larsen dual band with a built-in spring. I'm certain the reception/gain will not be as good as the Larsen NMO 2/70 I have, but it is supposed to hold up better to some abuse

I don't have much time with the Larsen NMO 2/70 SH but it seems a fair performer so far and is definitely sturdier for the car wash or off-road. My first trip off-road was with the standard Larsen NMO 2/70 and it lasted most of the day despite getting knocked around by low branches. However, as we were making our way off the trail, the coiled portion of the antenna got caught in a low branch and pulled the whip right out of the coil! I stopped immediately (I watched it happen) but couldn't find the black stick of an antenna in the woods full of black sticks. Oh well, the whip alone was only $16 on my next order from HRO.

I tried the Diamond NR 770 on the way home from the trail (I had it in the back as a spare). I mounted it on the existing NMO mount I have on a hood-groove tab. Performance was definitely sub-par compared to the Larsen NMO 2/70 but this is a 1/2 wave antenna and I didn't have the required/recommended matching Diamond coax in place (just the Larsen I'd previously installed).

Since that trip, I've mounted the Diamond NR 770 on the ARB bull bar tab (it required no enlarging of the hole) and I ran the matching Diamond coax to it. The performance now is MUCH better than when it was mounted on the hood groove tab, but probably isn't a fair comparison as I didn't have the matching coax connected (the 1/2 wave antenna uses the coax as a counterpoise which is why I ordered it for the bull bar location which has a relatively poor ground (image) plane).

I can't really say whether the Larsen NMO 2/70 mounted on the hood is better/worse than the Diamond NR 770 mounted on the bull bar with matching coax as I don't have enough test time yet. But I can say that both are very good performers in their given locations and each is better than the other if the other was mounted in the same location (i.e. the Larsen does not do well on the bull bar and the Diamond did not do well on the hood). I have both installed and connected via a switch so I can test them in real-time. I'll let you know if anything changes, but I don't expect it will.

I have yet to connect the Diamond SG 7500 or the Larsen NMO 27 (time is short - and the 80 is starting to look like an up-side-down porcupine already).

Miescha, trick tabs are a better option than the flat tabs used for lights. A shop would only charge a few bucks to weld one on for you.

Actually, I think it was STU050 that was referencing light tabs for the antennas - but either way, those are some pretty nice mounts you linked from tech tabs! Better still, I can weld them in place myself even with my meager skills (the Miller Trailblazer and mig gun with suitcase feeder make up for my poor skills ).

Thanks for the link!

 

[JMZ-]

Miescha,
Thanks for your wonderful advice. I'll go with HRO.

I like the black NMO 2/70B. My stupid question is that do I need soldering if I only buy NMO 2/70B and NMO-K coax kit? Will that make a cleaner finish than wirh FME and adapter?

For the mount, I do prefer the simple "L" bracket. Just read some complain of Larsen mount rusting issues on eHam review. That's why I'm thinking of Dimond K400C. But I'd like to mount the antenna on fender rather than hood.

Thanks.

 

[Miescha]

I like the black NMO 2/70B. My stupid question is that do I need soldering if I only buy NMO 2/70B and NMO-K coax kit? Will that make a cleaner finish than wirh FME and adapter?

The NMO-K coax kit from Larsen comes with a PL-259 connector that must be soldered in place - unless you specifically request the NMO-K with FME termination. Visit www.k0bg.com for directions on exactly how to properly solder the PL-259 connector as there is some key methodology (though many hams think it isn't that important). You'll find a ton of other great info on his site also.

If you order the kit with FME termination, you just need to add the FME-to-PL259 adapter for your radio (or FME-to-BNC adapter if using a typical handheld).

I didn't know the FME termination option existed until my last order when I expected to receive three (3) NMO-K kits with the soldered PL-259 but instead received one as expected and two (2) with the FME termination (and no adapter ). But HRO made good by sending me two adapters at no charge and also sent the correct NMO-K kits with solder PL-259 ALSO AT NO CHARGE Nice recovery on their part, so I'm pretty happy.

As I have little experience with FME termination, I don't know if there is a downside in terms of signal loss or the like. All I can say is that it was slightly harder to fish the cable through the firewall - but only slightly. It wouldn't discourage me from using it again in the future (especially as I have two sitting on the shelf now). Also, the matching coax that I ordered for the Diamond NR 770 antenna had the FME termination (but included the PL-259 adapter). I have this in use right now and seems fine - but again, I have nothing for direct comparison.

For the mount, I do prefer the simple "L" bracket. Just read some complain of Larsen mount rusting issues on eHam review. That's why I'm thinking of Dimond K400C.

I don't have enough experience to say as my two larsen brackets have been in use only two months. I do think the eham reviews tend to be pretty fair and accurate (even though I see occassional antenna reviews that make no sense). The Diamond mounts I've seen look terrific and appear to be made very, very well. They are a favorite among 80 owners here on mud (especially for mounting on the upper rear hatch). I have no experience with them, but I wouldn't hesitate to buy one if it fit my needs (and likely will in the near future).

But I'd like to mount the antenna on fender rather than hood.

I'm not sure I'm following you here. The typical "L" bracket slides into the groove between the hood (or bonnet) and the front quarter panel (or fender). It actually mounts to the fender, but uses the flat area of the hood (bonnet) for its ground (image) plane. I can take a pic if that would help.

My only point is that if you are mounting somewhere with a decent image plane, then the 5/8 wave antenna will perform better than the 1/2 wave. However, if you are mounting somewhere with a relatively poor image plane, then I think the 1/2 wave antenna will perform better as it uses the matched coax for a counterpoise (the coax is part of the image plane).

I hope this helps - Good luck.

 

[JMZ-]

That's really helpful, thanks so much.