Multiple Antenna Question for 2M/70CM

[ccg_ga]

Not sure if it would fit under the hood, but I fabricated mine out of 1/8" or so aluminum bar stock.

This is what I fabricated onto a roll bar clamp mount. The NMO mount was recycled off an old mag mount base.


The challenge you'll have is making the NMO mounts fit. They are designed for thin sheet metal, like the roof of a car. You can get thick mount NMO's that will handle much thicker mounts, but you'd have to replace yours. You could probably get creative with some aluminum stock and make a brace for the ones you have.

That would actually probably fit under the hood as there is a gap between it and the fender when it is closed. I was thinking get 2 of the same Laird mounts and use some type of adhesive to stick them together then mount that in the same place as the current one. I think the NMO mount might fit since it will still be thin more or less. Good suggestion on the aluminum, I will check that out as another option. I wish I had more metal fab tools so I could just make something custom.

We were talking about limb risers on the trail yesterday (the thin metal lines that are attached to the fender and top of the windshield if), I figured the extra metal that close to the antennas would cause an issue, so I was thinking of maybe trying to make some out of a strong plastic/synthetic material.

Are there by chance any type of plastic case or covers (for lack of a better word) that go around the coil on the 2/70B? That is what kept getting snagged by the tree limbs and pulled the antenna.

 

[ccg_ga]

The GMRS radio worked on the trail yesterday as well.

 

[mmckenna]

We were talking about limb risers on the trail yesterday (the thin metal lines that are attached to the fender and top of the windshield if), I figured the extra metal that close to the antennas would cause an issue, so I was thinking of maybe trying to make some out of a strong plastic/synthetic material.

Yeah, a synthetic line would probably work great. I was going to put some of those on my Polaris Ranger, but the angle is really weird.

Are there by chance any type of plastic case or covers (for lack of a better word) that go around the coil on the 2/70B? That is what kept getting snagged by the tree limbs and pulled the antenna.

I've never seen any.

 

[WA8ZTZ]

Weed whip line for the limb risers and shrink tube on the antenna coil may help.

 

[ccg_ga]

Weed whip line for the limb risers and shrink tube on the antenna coil may help.

Thanks - good suggestions! I'll check into the weed eater line.

 

[mancow]

Based on a couple of hours reading after I posted this I now understand that mounting any antenna in this location is a horrible idea.

It looks like my only option is to mount it on one of the front fenders - so still interested in any fender/lip mount or antenna suggestions.

It's not that bad. I have a quad band 10/6/144/440 on the same mount and it sweeps good and works fine.

Only difference is I cut a short bit of aluminum flat stock and drilled two holes. I mounted it using the antenna 3/8" hole with a bolt and drilled a hole in the bar for the antenna. That moved it over toward the edge some and allowed the angle forward and back to be adjustable.

 

[ccg_ga]

Here is take 2 on the antenna mounting brackets. I used 2 of the Laird straight brackets and some clear epoxy to bond them together. The NMO mount still fits fine and it feels much stiffer. I ended up putting a piece of heat shrink on the antenna coil also.

 

[ladn]

Are there by chance any type of plastic case or covers (for lack of a better word) that go around the coil on the 2/70B? That is what kept getting snagged by the tree limbs and pulled the antenna.

Some vendors may have NOS (New, Old Stock) of the old style closed coil whip. Otherwise, heat shrink tubing over the coil.

 

[ccg_ga]

@mmckenna @ladn

So I think the LED on the switch I have now is staying lit even when in the off position and is slowly draining the battery. I went out to crank it yesterday after sitting for about a week and the battery was nearly dead.

This SPDT switch looks like it is the same dimensions as the current switch, so I was looking into swapping the switches out. Can I use this one?

Contura II Switch SPDT Black - ON-OFF-(ON) - Blue Sea Systems

Specifically manufactured for use in Blue Sea Systems Contura Water Resistant Panels

www.bluesea.com

On the wiring, would this be correct:

- LED Ground > Ground to body
- Load 1 > Ignition switched power
- Power > Relay Pin 86
- Load 2 > Constant 12V power

 

[mmckenna]

The "Load 1" position is shown as momentary, so that's not going to work.

By the time you purchase switches, relays, deal with drained batteries, purchase different switches, you'll get a lot of headaches and spend a lot of money.

Yes, with the correct switch, you can make this work.

Or, you can just purchase the Lind timer I linked to earlier and be done with all this. It'll protect your battery and do it all automatically. They do cost more initially, but they pay for themselves in the long run.

 

[ccg_ga]

The "Load 1" position is shown as momentary, so that's not going to work.

By the time you purchase switches, relays, deal with drained batteries, purchase different switches, you'll get a lot of headaches and spend a lot of money.

Yes, with the correct switch, you can make this work.

Or, you can just purchase the Lind timer I linked to earlier and be done with all this. It'll protect your battery and do it all automatically. They do cost more initially, but they pay for themselves in the long run.

Got it, fair point. I checked the battery again and it has drained 50% since it was fully charged last night so this sounds like the way I need to go.

I went back and looked at the thread (wiring for car-battery, fuse block, etc.) where you mentioned the Lind timer and it was the SDT1230-014 model. I checked on the Lind page and there are 19 different models for 11-16V input, so is this the correct one to go with?

I pulled one of the instruction manuals from the Lind website and read through it. On the wiring, and placement within the system are these correct?



To Ignition Switch - Ignition switched power (currently hooked to a 10A fuse tap on the OEM interior fuse block for the DPDT switch)

To Vehicle Ground - Ground to Jeep chassis

The instruction manual said that both the GRD and IGN connections carry very little current, so would 14 ga wire be sufficient for this ground or should I use the 8ga wire to ground it?

To Battery Positive (+) - Red 8ga battery positive wire after the 1st maxi fuse block?

I have the 2nd maxi fuse block mounted in the interior and the 8ga red battery positive goes from the 2nd maxi fuse block to the positive terminal on the Blue Sea distribution fuse block. Should I just remove the 2nd maxi fuse block and mount the timer in its place?

It would go battery positive > 1st maxi fuse block > interior of the Jeep > Lind timer 'To Battery (+)' terminal

+OUT - To the positive terminal on the BS distribution fuse block still (still using the 8 ga red positive wire).

I guess I can just take DPDT the switch out completely as well if I go this route or can I leave it in place if I wanted to run the radios without the Jeep on?

 

[ccg_ga]

@mmckenna

One other thing I was thinking about today for my Uniden SDS100 scanner. I have been reading a bunch of wideband antenna posts from the scanner antenna sub-forum. I'd like to get a wideband antenna for the Jeep as well, mainly to monitor between 150-173, 406-463 and 765-857 frequency bands mainly for awareness or weather while off-road.

I've seen multiple suggestions for the Larsen NMO 150/450/800 and 150/450/758 antennas, but the Laird WPD136M6C-001 caught my attention because it covers 136-174/380-520/760-870. Could I get away with mounting it on the front fender also since it's really just for reception only or could it cause issues with the GRMS or Ham radios? If I can I was thinking of putting it on the passenger fender where the GMRS antenna is. I also thought about mounting it on the tire carrier again, but the antenna is 20" and it's about 23" from the mounting surface on the tire carrier to the soft/hard top. I also looked at the PCTEL Maxrad PCTWSLMR and the Austin Spectra.

Is RG58 fine for the scanner antenna or should I look at LMR400 or RG6? I'm also trying to find a way to hardwire the power lead for the SDS100 but I haven't come up with anything yet. It looks like Uniden doesn't make hardware cables for it yet and I was thinking of trying to rig up some type of USB power solution that ties into the BS distribution fuse block.

I need to stop reading all this stuff or I am going to go broke...

 

[ladn]

've seen multiple suggestions for the Larsen NMO 150/450/800 and 150/450/758 antennas, but the Laird WPD136M6C-001 caught my attention because it covers 136-174/380-520/760-870. Could I get away with mounting it on the front fender also since it's really just for reception only or could it cause issues with the GRMS or Ham radios?

You are a Jeep owner, so you know what it's like to fill a black hole with $$ Radio just makes the hole deeper.

Since the scanner antenna is RX only, I'd try a less expensive antenna first, like maybe an 19" whip, and you don't need any fancy cable. Try to keep the length as short as practical and be careful of it routing.

 

[ccg_ga]

You are a Jeep owner, so you know what it's like to fill a black hole with $$ Radio just makes the hole deeper.

Since the scanner antenna is RX only, I'd try a less expensive antenna first, like maybe an 19" whip, and you don't need any fancy cable. Try to keep the length as short as practical and be careful of it routing.

Oh isn’t that the truth. The rear locker won’t engage right now so I’m sure that is going to eat up some
more $.

Do you think I can get away with mounting the scanner antenna on the front fender or would it be best to put it up high on the rear tire carrier?

Good to hear on the RG58. I can use the stripper and crimp tools for this project too!

 

[mmckenna]

Got it, fair point. I checked the battery again and it has drained 50% since it was fully charged last night so this sounds like the way I need to go.

I went back and looked at the thread (wiring for car-battery, fuse block, etc.) where you mentioned the Lind timer and it was the SDT1230-014 model. I checked on the Lind page and there are 19 different models for 11-16V input, so is this the correct one to go with?

Yes, I have a few of those.

To Ignition Switch - Ignition switched power (currently hooked to a 10A fuse tap on the OEM interior fuse block for the DPDT switch)

To Vehicle Ground - Ground to Jeep chassis

The instruction manual said that both the GRD and IGN connections carry very little current, so would 14 ga wire be sufficient for this ground or should I use the 8ga wire to ground it?

14 gauge would be fine.

To Battery Positive (+)

- Red 8ga battery positive wire after the 1st maxi fuse block?

I have the 2nd maxi fuse block mounted in the interior and the 8ga red battery positive goes from the 2nd maxi fuse block to the positive terminal on the Blue Sea distribution fuse block. Should I just remove the 2nd maxi fuse block and mount the timer in its place?

Yes, that would work. You don't need the second fuse. That would be a good place to mount this. They are pretty durable, but not waterproof, so you wouldn't want it under the hood.

It would go battery positive > 1st maxi fuse block > interior of the Jeep > Lind timer 'To Battery (+)' terminal

Yes.

+OUT

- To the positive terminal on the BS distribution fuse block still (still using the 8 ga red positive wire).

Correct. That will disconnect power to the BlueSea fuse block when the timer runs out. So that will kill power to everything on that fuse block.

I guess I can just take DPDT the switch out completely as well if I go this route or can I leave it in place if I wanted to run the radios without the Jeep on?

So, what you could do is get rid of the switch you have now. Replace it with a single pole single throw (SPST) Momentary switch. Wire power from an always on source to that switch. Take the output of that switch and connect it to the Ignition input terminal on the Lind timer. What that will let you do is momentarily apply power to the ignition input on the Lind timer. That will reset the timer and turn your radios on until the timer runs out again. That's handy if you want to sit for a bit with the engine off but keep the radios on.
Our patrol cars are set up that way, it's handy if they are just sitting somewhere with the engine off and keep the radios on. Since it's a momentary switch (you could use a simple push button, too), it won't get accidentally left on.

 

[mmckenna]

@mmckenna

One other thing I was thinking about today for my Uniden SDS100 scanner. I have been reading a bunch of wideband antenna posts from the scanner antenna sub-forum. I'd like to get a wideband antenna for the Jeep as well, mainly to monitor between 150-173, 406-463 and 765-857 frequency bands mainly for awareness or weather while off-road.

I've seen multiple suggestions for the Larsen NMO 150/450/800 and 150/450/758 antennas, but the Laird WPD136M6C-001 caught my attention because it covers 136-174/380-520/760-870. Could I get away with mounting it on the front fender also since it's really just for reception only or could it cause issues with the GRMS or Ham radios? If I can I was thinking of putting it on the passenger fender where the GMRS antenna is. I also thought about mounting it on the tire carrier again, but the antenna is 20" and it's about 23" from the mounting surface on the tire carrier to the soft/hard top.

You want some separation between the transmit antennas and the scanner antenna. If it's too close, the transmitted RF can get coupled to the scanner antenna and route some of that RF energy into the scanner. Too much and it'll let all the magic smoke out of the soft expensive bits inside your scanner.

I'd find somewhere else to mount it. And from my calculations, you are running out of room for antennas…. You might have to get creative.

I also looked at the PCTEL Maxrad PCTWSLMR and the Austin Spectra.

Laird, Larsen and PCTel/Maxrad are all higher end commercial antenna brands. Austin Spectra seems to focus on hobby grade stuff. I'd stick with one of the commercial brands. While I have never owned an Austin Spectra, I have owned other hobby/amateur grade antennas, and they were all a disappointment. I don't own any of them anymore, and replaced everything I have with either Larsen or Laird.

Is RG58 fine for the scanner antenna or should I look at LMR400 or RG6?

RG-58 is just fine. LMR-400 is way to big to route in a vehicle, and RG-6 won't do anything for you that the RG-58 can't in any length you'd need in a Jeep.

I'm also trying to find a way to hardwire the power lead for the SDS100 but I haven't come up with anything yet. It looks like Uniden doesn't make hardware cables for it yet and I was thinking of trying to rig up some type of USB power solution that ties into the BS distribution fuse block.

And this is why some like mobile scanners over using portables.
There are 12 volt to 5 volt USB converters. They are cheap and you can find them online. Problem is some of them are really noisy on the RF side and can wipe out your other radios.

I need to stop reading all this stuff or I am going to go broke...

Yeah, but you know what will make you go broke faster? Constantly buying low tier radios, antennas and other parts, and having to replace them all the time. Like I said earlier, I have 30 year old Larsen antennas. I paid more for them than the hobby/hammy grade stuff, but I've long since made my money back on them. Do it right the first time, and it'll save you money in the long haul.

 

[mmckenna]

Do you think I can get away with mounting the scanner antenna on the front fender or would it be best to put it up high on the rear tire carrier?

Didn't you have a CB antenna back there? If you do, you want the antennas separated by a few feet at least.

 

[ccg_ga]

So, what you could do is get rid of the switch you have now. Replace it with a single pole single throw (SPST) Momentary switch. Wire power from an always on source to that switch. Take the output of that switch and connect it to the Ignition input terminal on the Lind timer. What that will let you do is momentarily apply power to the ignition input on the Lind timer. That will reset the timer and turn your radios on until the timer runs out again. That's handy if you want to sit for a bit with the engine off but keep the radios on.
Our patrol cars are set up that way, it's handy if they are just sitting somewhere with the engine off and keep the radios on. Since it's a momentary switch (you could use a simple push button, too), it won't get accidentally left on.

Got it - I ordered the Blue Sea switch below. I believe this is the correct SPST momentary model from the pin out diagram. Does it look correct?

Contura II Switch SPST Black - OFF-(ON) - Blue Sea Systems

I think the only other question was on the relay pin 86. It is currently connected to the center pin on the DPDT switch. Does the shut-down timer take the need for that pin out of the system or do I still need a way to trigger the relay?

Do you think I can get away with mounting the scanner antenna on the front fender or would it be best to put it up high on the rear tire carrier?

I do, but I think it's time to remove it along with the CB as well. I have an idea on how to make a mount using 2" aluminum bar stock and a NMO mirror mount that will allow me to raise the NMO base up so the antenna extends about the roofline. I just need to figure out the clearance for the garage. The Laird WPD136M6C-001 is 19.5", so I think that may work. That would leave me with just the scanner antenna on the tire carrier and nothing else. I think I am officially out of room after this one is installed.

More details to come if this looks like it will work.

And this is why some like mobile scanners over using portables.
There are 12 volt to 5 volt USB converters. They are cheap and you can find them online. Problem is some of them are really noisy on the RF side and can wipe out your other radios.

Thanks for the suggestion, I'll dig into this and see if I can find anything that is quality enough to warrant installing to the distribution fuse block.

 

[mmckenna]

Got it - I ordered the Blue Sea switch below. I believe this is the correct SPST momentary model from the pin out diagram. Does it look correct?

Contura II Switch SPST Black - OFF-(ON) - Blue Sea Systems

Yes, that switch will do what you want.

I think the only other question was on the relay pin 86. It is currently connected to the center pin on the DPDT switch. Does the shut-down timer take the need for that pin out of the system or do I still need a way to trigger the relay?

The timer has the relay built in. Bypass the relay completely, remove it.

I do, but I think it's time to remove it along with the CB as well. I have an idea on how to make a mount using 2" aluminum bar stock and a NMO mirror mount that will allow me to raise the NMO base up so the antenna extends about the roofline. I just need to figure out the clearance for the garage. The Laird WPD136M6C-001 is 19.5", so I think that may work. That would leave me with just the scanner antenna on the tire carrier and nothing else. I think I am officially out of room after this one is installed.

Those antennas are beasts. And not in a good way. The base is very wide and sticks up quite a bit. If it hits a branch, something is going to break. Might be the branch, might be the antenna, might be the mount. If you go with that antenna, keep it down low so the spring will protect the whip. Keep the base down out of the way.
Or, better yet, go with the Larsen with the spring base lower down.

 

[ladn]

Do you think I can get away with mounting the scanner antenna on the front fender or would it be best to put it up high on the rear tire carrier?

You want to keep it as far away from your transmit antennas as possible. As @mmckenna said, you're running out of room.
Will it will be far less than optimal, will your SDS 100 receive what you want using the stock rubber duckie antenna on the radio inside the vehicle? If that will give you acceptable performance, you'd have one less mounting problem and that would mitigate RF overload.