Amateur Mobile Antenna Questions

[yaknamedjak]

Hi, sorry for this being an amateur question, I'm new to mobile radios/antennas.

First question: I currently own the following antennas relevant to this question:

Laird 1/4 wave VHF whip
Laird 1/4 wave UHF whip
The big whip from laird that does UHF/VHF/800 I think model # starts with WPD.


The equipment I'm installing is:
MCS2000 VHF
MCS2000 UHF
BCD536HP

My initial thoughts were to use the respective quarter waves for their respective radios and the wideband for the scanner.

Should I be doing it a better way? I don't mind having all the antennas up there at all, there are already four holes drilled in the roof. Just want to do it right.


There's also a cellular band laird phantom to go up and I need to get a GlobalSat unit to throw up there as well. (If anyone has a suggestion on a GlobalSat unit to get and how to connect one to the scanner as well as a laptop, I'd be glad to hear it. My ToughBook has a GPS built in but it kind of sucks so I might as well stick one on the roof.

I may have to make another thread asking about spacing since I'm not sure if the current spacing is correct seeing as the VHF MCS2000s is 110w, though I plan on dialing the high power mode back a bit if I can figure out how.

WX4EMT is sort of my role-model for this install.


Also, can anyone knowledgeable confirm that the models in the attached screenshot are the antenna mounts I'd need for the above antennas? Is Antenna Farm currently closed for business?




Thank you in advance to anyone who can help me, I'm grateful such a knowledgeable community exists.


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[12dbsinad]

Looks like you got it right. Quarter waves for the MCS's are the way to go and will give you wide band capability. They are what I run on my pickup and work fine.

 

[mmckenna]

Yeah, I agree, 1/4 waves give you a lot of useable bandwidth, which can be nice for amateur, LMR, interop, etc. I run only 1/4 wave antennas on my work and personal radios due to the wide spread of frequencies I need to use.

The multiband will work for your scanner. That antenna is an overkill, probably might be used better somewhere else, but it'll work fine.

As for the satellite antenna, you really need to do some research. A vertical antenna isn't what you want. A patch antenna is usually what comes with the Iridium phones. The purpose built mobile antennas for satellite phones is usually a dome type. NMO mount probably isn't going to work.

 

[yaknamedjak]

Thank you both for your replies. Looks like I'll stick with the setup I imagined.

I'll probably add a spacing photo on here tomorrow to see what you and others think.

Would either of you be able to confirm those mounts? The bottom item in the screenshot is for the MCS2000s, middle for scanner, top for 4G.

Yeah I do realize the tri band WPD is a beast, but don't have anything else to use it for, I bought it for this vehicle since WX4EMT raved about it so much. With the right connectors I imagine it could feed all three radios somehow, ha..anyway I'm fine using it just to scan, or maybe for other radios in the future, not sure. Also, haven't decided yet on the custom PDU or ChargeGuard...the PDU came in but I haven't really opened it yet.


@mmckenna Yeah well not for satellite phone use just for GPS. GlobalSat makes some hockey puck units, WX4EMT used one on his 2011 Chevy Tahoe install if you're familiar with the thread. Thinking a puck-type, just not sure which one and how it would interface ideally with both scanner and laptop.


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[mmckenna]

OK, if it's just for GPS, Larsen makes a GPS specific NMO antenna that should work well. I think it uses one of the NMOHF mounts, but confirm before you purchase.

For all your antennas, the standard NMO should work fine.
The Motorla's need a "Mini-UHF" type connector. I didn't see those on your list.
The list itself looks fine. The NMO mounts with RG-58 will work fine for the VHF and UHF radios as well as the scanner.
For the GPS and Cellular, you might want to consider something with a bit less loss, but usually in a mobile environment, the length isn't enough to make that much of a difference. There is an RG-58 dual shield that has a bit less loss. That would be helpful for GPS and Cellular. You could even try LMR-200, or LMR-240, but they can be a bit stiff and harder to route.

 

[Rred]

I don't know how old that Toughbook is, and Toughbooks in general lag a generation behind in technology. But even 10 years ago, an inexpensive portable GPS could be jammed between the sun vior and the metal roof of a car, and STILL pick up signals and work 1000% normally. Anything with a "Gen4" fourth generation GPS chip will do this. Third generation usually will do this as well. They'll also often work indoors, through building roofs and with just a skyview through a window, when older equipment wouldn't.
Dedicated roof antenna for a GPS? These days? There are too many other good options.

 

[yaknamedjak]

It's old. Mk5 Cf-18 but it's in mint condition and still works well for me. All my CPS is on it, monitor dispatch command center screen and weather, and can run EMS call sheets if needed. But yeah the GPS tends to take a while to locate... Can you recommend a good solution that would allow me to feed GPS to the laptop and the scanner? Appreciate your insight.


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[Rred]

There are many "GPS pucks" on the market now. I would check online, look for SirfStar4 or similar G4 technology and a Bluetooth connection, so you can leave the puck on the dashboard if that's good enough for you. You'd need to consider battery run time or whether it can plug into a power cord if that's an issue, and if your laptop has no Bluetooth, add a tiny bt dongle in the USB port. Also cheap enough, they barely stick out of the socket now. Avoid the cheapest no-name GPSes and look for a brand and warranty, or at least a reputable vendor who gets good feedback.

 

[yaknamedjak]

Thanks. How would I go about getting the data to both the laptop and the BCD536HP?


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[Rred]

I don't know if they can share one GPS. That would depend on whether they use BT or USB and the specifics of the drivers, and whether they would tolerate sharing. You might ask Bearcat if they have any known solutions for that.

 

[Project25_MASTR]

Immediately I was thinking, man this would be a great place for a Sharkee since it fits in a standard 3/4" hole.

Anyway, Panorama (it's actually an accessory for the Sharkee) makes a "splitter" which can feed two GPS receivers from a single antenna (it only sends power from one receiver).

 

[yaknamedjak]

Immediately I was thinking, man this would be a great place for a Sharkee since it fits in a standard 3/4" hole.

Anyway, Panorama (it's actually an accessory for the Sharkee) makes a "splitter" which can feed two GPS receivers from a single antenna (it only sends power from one receiver).

Thank you! I accidentally just made a new thread to ask about the splitting before I saw your post. I'll look in to this now.

[Edit] I'm going to reply to you on the other thread to help anyone else who might go searching for this.

 

[yaknamedjak]

Also, so far all the antennas I have are Laird, as mentioned above. I've been trying to get Laird mounts as you can see in the cart screenshot up there.

Neobits wants like $48 to ship them. Antenna Farm seems like it's closed, can't put payment method in during checkout process. Is there anywhere else to get them? Or is there another brand someone could recommend as being quality? Does it matter? I need them by Friday since my headliner will be down after some roof work at the shop.

NMO->SMA for the cellular
NMO->BNC for the 536HP
2x BMO->Mini UHF for the MCS2000s


Thanks again to everyone for your assistance, I realize I'm being rather needy but I'm new to this and there's so much to gain from the members of this forum.

 

[yaknamedjak]

Ordered from WPSAntennas.com

Antenex is Laird right? Same quality?

Ordered from WPSAntennas, hope this order looks right. Expensive. We'll see how it goes.

 

[mmckenna]

Antenex, Laird, Larsen, ComTelco are all good companies. NMO is a standard mount, so it doesn't matter what brand you purchase.

I'd recommend avoiding Browning, Tram or any other Chinese brand. What little money you save won't be worth it in the long run.

Prices look "OK", but not great. I install my own connectors, so it's a lot cheaper for me. Basically you are paying extra for the installation and (hopefully) testing. If you don't have the tools or experience in installing these connectors, it's worth the extra money. Purchasing the crimpers, burning through a few connectors making mistakes, etc. can get expensive. If this is all you are doing, then it's a good deal. If you were going into the installation business or had plans to do this frequently, it would be worth buying the tools and learning how to do it.
Other benefit of "rolling your own" is that you can cut the cable to the length you need. 17 feet might be more than what you need in your installation, so you'll have to find a way of dealing with the extra cable. Loss wise, I wouldn't worry about it. A few extra feet isn't going to break anything.

 

[yaknamedjak]

Antenex, Laird, Larsen, ComTelco are all good companies. NMO is a standard mount, so it doesn't matter what brand you purchase.

I'd recommend avoiding Browning, Tram or any other Chinese brand. What little money you save won't be worth it in the long run.

Prices look "OK", but not great. I install my own connectors, so it's a lot cheaper for me. Basically you are paying extra for the installation and (hopefully) testing. If you don't have the tools or experience in installing these connectors, it's worth the extra money. Purchasing the crimpers, burning through a few connectors making mistakes, etc. can get expensive. If this is all you are doing, then it's a good deal. If you were going into the installation business or had plans to do this frequently, it would be worth buying the tools and learning how to do it.
Other benefit of "rolling your own" is that you can cut the cable to the length you need. 17 feet might be more than what you need in your installation, so you'll have to find a way of dealing with the extra cable. Loss wise, I wouldn't worry about it. A few extra feet isn't going to break anything.

Thanks for your confirmation. Appreciate the knowledge. Totally agree, if I were doing this more definitely worth it to roll my own, like my Cat6 cables at the office.

Also I ended up adding another SMA to the order, since it seems like I can run two of the 4G Laird phantoms to a cradlepoint device. Ordered another phantom as well. This install is getting awfully expensive.

 

[Astro_Spectra]

Be a bit cautious with 100W radios when you have antennas close. I've had to repair VHF radios (non-name marine and Moto) taken out by high-power UHF radios when antennas were mounted only 3 feet apart.

 

[yaknamedjak]

Be a but cautious with 100W radios when you have antennas close. I've had to repair VHF radios (non-name marine and Moto) taken out by high-power UHF radios when antennas were mounted only 3 feet apart.

Thank you, will try to. If I can figure it out how, I'd probably like to dial the VHF MCS2000 down to about 65% operating power, though I don't have any kind of test equipment.

I do plan on posting some photos of how the holes are drilled in the roof currently so I can get some advice on ideal antenna layout before they go in and get wired up. The vehicle is former state trooper with 4 NMOs (that I'll be replacing) installed, but I don't think they were using anything that high power. I'll have to drill one more NMO for the second 4G that's on the way, and another hole for the GPS.

Of the listed equipment, which antennas should be the farthest apart?

 

[mmckenna]

Thank you, will try to. If I can figure it out how, I'd probably like to dial the VHF MCS2000 down to about 65% operating power, though I don't have any kind of test equipment.

That's pretty common practice around here. Reality is that most departments do not need 100 watt radios. Even CalFire here in California, who does wildfire suppression has switched to 50 watt radios as their standard.
The PD I look after had to have 100 watt radios (if 50 watts is good, 100 must be better, right?). I had the shop that did the installation turn them all down to about 80 watts. The radios will thank you for this.

I do plan on posting some photos of how the holes are drilled in the roof currently so I can get some advice on ideal antenna layout before they go in and get wired up. The vehicle is former state trooper with 4 NMOs (that I'll be replacing) installed, but I don't think they were using anything that high power. I'll have to drill one more NMO for the second 4G that's on the way, and another hole for the GPS.

Of the listed equipment, which antennas should be the farthest apart?

The Motorola equipment should have pretty good filtering on the front ends, so you should be OK with those with some reasonable spacing. I've always done at least 1/4 wavelength on the lowest frequency, but that has always been with 50 watt radios. I've heard people say 1/2 wavelength, which would be better if you have the space.

The scanner is the one you should be concerned about. They have very wide front ends with little filtering. Pretty easy for those to get popped by a 100 watt VHF or UHF radio.

GPS antennas will probably be OK either way. Many manufacturers sell antenna mounts with the GPS and NMO base on the same mount.

Physical location would depend on the existing hole locations. Photos would be helpful.

Other thing to consider is feed line losses. Since higher frequencies suffer more from feed line losses, you might want to have your UHF radio be the shortest cable run followed by the VHF, then the scanner. The GPS shouldn't matter since most of them have some sort of amplification built into the antenna module.

 

[yaknamedjak]

That's pretty common practice around here. Reality is that most departments do not need 100 watt radios. Even CalFire here in California, who does wildfire suppression has switched to 50 watt radios as their standard.

The PD I look after had to have 100 watt radios (if 50 watts is good, 100 must be better, right?). I had the shop that did the installation turn them all down to about 80 watts. The radios will thank you for this.

Yeah, I'm gonna see if I can figure it out.




Finally got around to getting a couple (crappy, sorry, didn't have time to bust out the drone to get some proper ones) photos of the roof. You can see some rust and marks from previous equipment, my next step before the install is having the roof re-painted and the holes covered with "knickels" as the body shop called them. Anyhow it's $450 and I'm waiting till I have a couple days that I can drop it off.

Didn't have my measuring tape with me but you can get an idea. I screwed the antennas on there to see how they'd look in that layout. It seems like perhaps it would be better to put the wideband in the rear-most spot, the VHF in the front and the uhf in the middle.

Plan to drill another for the other 4g opposite of where the one on there is for symmetry. Also plan to put the GPS forward of nmo that's currently forward-most.

Should I try to re-use holes like the one that was there for the lightbar control cable? It's filled with silicone.


TIA


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