Excursion Install

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Motradio
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Joined: Tue Jan 06, 2004 9:11 pm
What radios do you own?: HT1000, MTS2000, Maxtrac

Excursion Install

Post by Motradio »

Hi, looking for some Antenna help. Almost done with a stealth install of 2 100w MCS2000's in my 2003 Ford Excursion. I have 2 remote head units and speakers carved into the console of the truck (all mostly invisible). Radios are going under the 3rd row seat and nothing is really visible...yet.

The antennas are a problem, the truck is pretty tall and I can't pop much on the roof or I won't be unable to squeeze into the 6'8" parking structures that are common. My AM/FM antenna hits as it is so it's tight due to the height of the truck.

I have a Glass mount Antenna from Larsen (Dual Band) and would need one on each side of the truck, and it would look like something that says "RADIOS ARE IN CAR, PLEASE BREAK IN". They wouldn't get much but would likely mess up my ride. Also the larson dual band glass mounts are taller then the roof, but I think would survive the dragging under the parking structure but hard to say depending on how high I mount them on the windows. This is my fall back.

My idea for a hidden antenna would be to run a copper tape window antenna. I have seen a few folks that have tried them for stealth condo antennas but figured it might work for mobile work too. Basically make a 1/4 wave antenna with ground plane taped to the each of the side windows. I know it will be far from ideal and much lower gain then unity, but I'm willing to give up some performance for 'stealthy-ness' The use will be mostly for local repeaters all of which could be hit with a 5w HT.

I also have a Maxrad UHF low profile antenna and was also thinking about trying one in the back doors on the truck (They are fiberglass). Would have to do a ground plane but not at all sure about the fiberglass and the radiating pattern which would be horrible.

Any other interesting ideas besides mag mounts and pulling antenna's in?

This is not for public service, this is for Ham use in case that wasn't clear :)

Sandy
tvsjr
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Re: Excursion Install

Post by tvsjr »

I've done several Excursions/Super Duties. The back doors will suck... glass mount antennas won't withstand 100 watts and will suck... not sure I like the copper tape idea.

Have you considered an L-bracket on the front left, with a dual-band antenna like a RadiallLarsen NMO2/70? They are good performing antennas and won't be too "un-stealthy" across from your AM/FM antenna.

You could also consider two low-profile antennas on the roof, but you will need to reduce the power output to 50 watts, most likely. UHFs aren't terrible... VHFs are rather narrow bandwidth. VHF would work for ham, but don't expect to transmit across the full range of the radio... a few MHz is about it, at best.
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Motradio
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Re: Excursion Install

Post by Motradio »

I have one of the larson dual band NMO2/70 antenna's but was thinking I would need 2 of them since I have 2 radios. I have a duplexer but not really sure if it could work with a pair of separate radios since it would be possible to transmit to happen on either radio at the same time. Not that it would be often, but more by accident. I had thought of the cowl mount of the dual band Larsen antenna as it's black and not too obvious, but not sure if running 2 radios on one antenna is a good thing to do since these were I see most used for single radios that have multi-band capability and can't possibly xmit on both bands at the same time and 'I think' they also mute all receivers when any tx happens, just not sure and that is something I'm not going to try unless someone knows it's safe. And note: the Japanese instructions on the Diamond/Comet duplexer is of no help ;)

The tape antenna would be something I would try, and I don't think at 100watts with 3/8" or 1/2" copper wide tape would be an issue if properly loaded. Can't know till I fry a transmitter I guess, but for loading and matching that an easy check with the Antenna analyzer before I get to the fireworks :)

The low profile antennas on the roof really worry me as they would be just about the same height as my AM/FM antenna and that just nicks the cement roofs on some structures, I can only imagine what would happen if it caught one of those on something. I have used the UHF low profile with OK results, but was told that the VHF is essentially a Dummy load so don't waste the $$ one it ;)

Thanks for the ideas, would be interested to see if other have run the duplexers with multiple radios on one antenna, that might make this much easier and a better antenna then what I would hack up.

Sandy
tvsjr
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Re: Excursion Install

Post by tvsjr »

Diplexers (not duplexers - different beast) are either a low-pass/high-pass filter (for a two-port, say VHF/UHF) or a low-pass/band-pass/high-pass (for a three-port, say VHF/UHF/1.2). There's no muting of receivers, etc... just some filters.

You can use a diplexer with a VHF and UHF radio, transmit at the same time, no problem. They can also be used the other direction, as I do... one dual-band radio, two single-band antennas (height issues).

Maxrad makes a decent VHF/UHF diplexer if you want to get away from hammy-grade crap. If you really want to spend money, look at Sinclair's FX2300...
mmckenna
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Re: Excursion Install

Post by mmckenna »

My grandfather used to talk about using foil tape antennas on an aircraft they were working on that needed to be very quiet. They didn't want a whip whistling in the airflow. They used the foil tape and it worked fine.
Shouldn't be an issue to cut for 1/4 wave and ground to the truck body. Issues will obviously be reflections for the nearby sheet metal around the window, and the RF exposure issues from anyone inside the vehicle. Not to mention it will suck. I certainly wouldn't want to ride inside while you were transmitting with 100 watts, or even 50.

Dual band antenna opposite the AM/FM antenna with a diplexer would work, but you will have some shielding fro the cab. You can get the short dual band antennas that are 19 inches with either an open or enclosed coil in the middle. Not ideal, but probably the best option given the restrictions.

If you don't mind me asking, why do you need 100 watt radios when you can hit the repeaters with an HT?
Last edited by mmckenna on Thu Jan 05, 2012 6:03 pm, edited 1 time in total.
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Tom in D.C.
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Re: Excursion Install

Post by Tom in D.C. »

Here are some suggestions you might find useful in your search and decisionmaking:

1. http://www.diamondantenna.net/nr72bnmo.html

2. http://comtelco.net/PDF/A2543.PDF

3. http://www.dci.ca/pdf/qst-dec-2004.pdf

#1 is a dualbander that works quite well and is only 13 inches high.
#2 is a UHF low-profile unit with 3db gain
#3 lets you run two radios into one antenna or vice-versa

Both antennas are NMO mounts; the diplexer is SO-239 on all three connectors.
Tom in D.C.
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tvsjr
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Re: Excursion Install

Post by tvsjr »

I didn't know DCI was making a diplexer - good to know. They build nice stuff. I would call and see if you can get their box with a real connector on it (N, BNC) rather than SO239s...
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Motradio
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Re: Excursion Install

Post by Motradio »

tvsjr wrote:Diplexers (not duplexers - different beast) are either a low-pass/high-pass filter (for a two-port, say VHF/UHF) or a low-pass/band-pass/high-pass (for a three-port, say VHF/UHF/1.2). There's no muting of receivers, etc... just some filters.
Thanks, for the correction, and what's funny is I jut pulled the 2 that I Diamond Diplexer and Triplexer and I think the translation got lost as the MX72H has Duplexor on it as well as the packaging :)

This might make things go a bit smoother in coming up with something other then copper tape on the side window ;)

Sandy
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Motradio
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Re: Excursion Install

Post by Motradio »

Tom in D.C. wrote:Here are some suggestions you might find useful in your search and decisionmaking:

1. http://www.diamondantenna.net/nr72bnmo.html

2. http://comtelco.net/PDF/A2543.PDF

3. http://www.dci.ca/pdf/qst-dec-2004.pdf

#1 is a dualbander that works quite well and is only 13 inches high.
#2 is a UHF low-profile unit with 3db gain
#3 lets you run two radios into one antenna or vice-versa

Both antennas are NMO mounts; the diplexer is SO-239 on all three connectors.
Tom -

Thanks for the article! That is excatly the info I needed to know. The packaging for the models I have are written in most all Japanese. I have the Diamond MX-72H and the Diamond MX2000D Triplexer. I'm going to give them a try on the bench with the Larson 2m/70cm dual band that I have.

And that short diamond antenna may be an option. I have the Larson and it uses the same mount so might be just a good compromise.

TVSJR -

I'm in for the night, but where did you mount the antenna on the Superduty's, on the area like were the AM/FM antenna (through the plastic) or with a trunk mount to the hood? Trying not to drill any holes if possible.

Again thanks everyone, all this bits of info is keeping me moving!
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Motradio
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Re: Excursion Install

Post by Motradio »

mmckenna wrote:My grandfather used to talk about using foil tape antennas on an aircraft they were working on that needed to be very quiet. They didn't want a whip whistling in the airflow. They used the foil tape and it worked fine.
Shouldn't be an issue to cut for 1/4 wave and ground to the truck body. Issues will obviously be reflections for the nearby sheet metal around the window, and the RF exposure issues from anyone inside the vehicle. Not to mention it will suck. I certainly wouldn't want to ride inside while you were transmitting with 100 watts, or even 50.

Dual band antenna opposite the AM/FM antenna with a diplexer would work, but you will have some shielding fro the cab. You can get the short dual band antennas that are 19 inches with either an open or enclosed coil in the middle. Not ideal, but probably the best option given the restrictions.

If you don't mind me asking, why do you need 100 watt radios when you can hit the repeaters with an HT?
Yeah I found a few hits on line about home built aircraft and the 'Tape Antenna'. Works Ok if tuned correctly and 7000feet clear shot to the tower :)

I think the Diplexer will solve some of the antenna issue. And can get back to maybe the front cowl mount.

For the 100w of power, the radios have High and Low and what looks like about 70watts from the High UHF and a bit more on the VHF, low seems to be about 30w-40w and if the radios will do high power then the antenna should be able to, no real reason other then they can and I changed the Horn/Lights button to High/Low power. Not worried about power, the Diesel has 2 big batteries and a huge alternator. Nothing says overkill like a Diesel and Motorola...

Sandy
tvsjr
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Re: Excursion Install

Post by tvsjr »

Just a basic L-bracket that screws to the metal inside the quarter panel and emerges in the gap between hood and quarter panel. They use three #6 sheet metal screws and are not visible unless the hood is open.

I'll try to stay off my soapbox, but why are you concerned about drilling holes? It's an 8 year old truck. Do you think a couple NMO holes, some screw holes for an L-bracket, etc. are going to make any difference to the truck's trade-in value? If you keep it just 2 years, it's 10 years old (and likely high mileage)... it'll go to auction and either become a work truck or head south of the border. A few holes won't make a bit of difference. So, drill the holes you want, make the truck work for you, and don't worry about it.
mmckenna
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Re: Excursion Install

Post by mmckenna »

Motradio wrote:
Yeah I found a few hits on line about home built aircraft and the 'Tape Antenna'. Works Ok if tuned correctly and 7000feet clear shot to the tower :)

I think the Diplexer will solve some of the antenna issue. And can get back to maybe the front cowl mount.

For the 100w of power, the radios have High and Low and what looks like about 70watts from the High UHF and a bit more on the VHF, low seems to be about 30w-40w and if the radios will do high power then the antenna should be able to, no real reason other then they can and I changed the Horn/Lights button to High/Low power. Not worried about power, the Diesel has 2 big batteries and a huge alternator. Nothing says overkill like a Diesel and Motorola...

Sandy
Yeah, my grandfather worked on a couple of weird projects at Lockheed, including two quiet observation aircraft, the Q-star and the YO-3a (used for a bit in Viet Nam) He did the electrical systems and worked around some of the radio stuff. He said it worked fine for what they were doing, in fact, I still have a roll of the tape in my garage.

The diplexer you have likely will work fine for what you want. Expect to see some loss through them, however.

I hear you about the power, you've got what you've got, so might as well use it. I had a 1997 F250 with the 7.3 liter Diesel and it was a great truck. 2 batteries, so never a problem with power. I miss that truck a lot.

I think based on what you are trying to do, the "L" bracket, like TVSJR said, will work well. They are pretty low profile, and really easy to install. I used one for a while on one of my trucks for the same reason you are. There is a pretty good picture of one installed on this page, about half way down http://www.expeditionportal.com/equipme ... cle/part3/

Sounds like a pretty good set up based on your limitations. Post some pictures of your radio installation, I always like to see well hidden radios.
"The nice thing about standards is that there are so many to choose from."
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Motradio
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Re: Excursion Install

Post by Motradio »

That mount will do the job. Yeah, I would miss the rattling of pistons if I ever sold this truck. Every time I start it up it puts a smile on my face (except for having to do some injector work a couple of weeks ago...).

The funny thing is I think I got the diplexer years ago for a pair of Syntor's (yes your read right) that I had in the truck of my car. The price on the Diamond Diplexer package is 5,500 Yen. It's all coming back to me now...

The Diplexer that I already have and the Larsen 2m/440 antenna I already have will be most of the stuff I need, just a simple bracket and I have some of NMO cable assemblies that can be used on that bracket. And I'll bet the bracket is cheaper then a roll of copper tape ;)

Thanks again for the tips, I'm too close to the project to have come of with the simple solution!

Sandy
mmckenna
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Re: Excursion Install

Post by mmckenna »

Always helpful for me to get a second opinion. I have some strange fascination with mobile installs. I love doing them on my own vehicles, but no way I'd want to do that for a living. Too old for that stuff.

I used to refer to it as my "turbo grin" when ever I romped on the pedal. Loved the sound of that engine and the noise the turbo made when it spooled up. I remember when I first bought it, my brother and I headed over to Reno by way of Highway 80. Going up those long grades was a lot of fun. The truck just kept accelerating all the way up the hill and just wouldn't stop. I think I was up near 80MPH at one point and chickened out and pulled my foot out of it. Couldn't get over the felling of that much power. 4x4 too, I could pop in in 4wd low range and it would idle over anything, didn't even need to push the pedal!
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mike m
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Re: Excursion Install

Post by mike m »

Aircraft radios are typically only 10 to 20 watts of carrier power and similarly the antennas are only rated for around 25 watts maximum carrier power so they can get away with small radiators.


Don't even think about running 100 watts into any of the glass mount antennas, I would question any MFG. who says any of their antennas are rated for more than 50 watts.

Your MCS at 100 watts is not going to work very well with any of those antennas that you are thinking of using unless you drop the power output to under 50 watts and more preferably around 15 to 25 watts.

Also stay away from Comet and diamond Diplexers unless you are running 25 watts or less, I know that some say 100 watts but anymore they must mean pulse power because I haven't seen any that don't heat up real fast.

A portable FLIR IR scope looking at a diamond or Comet diplexer is really an eye opener as to what's going on inside under even 50 watts of RF power.

Do it the correct way, don't use mag mounts either at that power level, drill some holes in your vehicle and use real commercial antennas rated for more than 100 watts.

Mike
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