| Author |
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cooper
| | Posted on Thursday, June 06, 2002 - 01:53 pm: | 
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I have mine mounted on my ARB and it comes up about 5 or so inches above my mirrors, height wise. It's mainly used for trail use, within about one mile or so. It's a two footer. Will this work? |
Bill Bettridge (Billb)
| | Posted on Thursday, June 06, 2002 - 02:25 pm: |
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Mine works great mounted on the ARB - 4ft firestik though so it is well above the hood. I get as good a xmit & receive as many with above the roof antennas. |
Al Oliveira (Offroaddisco)
| | Posted on Thursday, June 06, 2002 - 06:54 pm: |
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The higher the antenns is mounted and with the best ground plane possible will give you the best performance. This is often on the roof since the bumper gives you a poor ground plane. The only problem is while off road an antenna that has snapped off because it hit a tree limb will be of little use for transmitting or receiving. In fact it's only use would be as a trail marker. So the bumper mount is just fine and has worked well for many here.
If you go UHF then a 1/4 wave (6") roof mounted antenna would be okay since they'll give more than a 2' fiberglass antenna. |
Mike Rupp (Mike_Rupp)
| | Posted on Thursday, June 06, 2002 - 06:55 pm: |
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A simple check would be to install the antenna and then check the swr. If the swr isn't too high you know that the antenna is radiating the energy away from the vehicle.
Read this:http://www.firestik.com/Tech_Docs.htm. It has a lot of good info about CBs.
Mike |
Paul T. Schram (Paulschram)
| | Posted on Friday, June 07, 2002 - 11:40 am: |
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Three erroneous comments here.
First off, the length of a quarter wave whip for 11 meters is closer to 102". Whoops, my bad, that was a reference to UHF. Sorry Al...
Secondly, the SWR of an antenna system does not give any indication whatsoever as to radiation effectiveness, efficiency, angle, nor pattern. A 50 ohm resistor will give you a perfect SWR, but not radiate well, if at all.
Third, the ground plane is not affected by the placement of the antenna. A ground at RF is more concerned with having things bonded to the same ground potential. It should be symmetrical around the base of the antenna, but most of the improvements gained by mounting an antenna on the roof are due to a better radiation pattern due to being above obstructions than the ground plane (reference-new-tronics insert with the new mast I just bought, the MO-4). It is best if the entire vehicle is bonded and grounded and acting as a counterpoise to the radiating element. A bumper might not make a good ground plane if it is electrically isolated from the frame of the vehicle, but I find that difficult to envision.
The reasons to mount an antenna as high as possible are essentially to reduce any coupling from other objects nearby which can and will affect your match (SWR) and radiation pattern, and absorbance of the RF by those same things.
A short (>1/4 wavelength physical dimension) has so many compromises that one is best trying to maximize what you have left. In order to do this and achieve the greatest degree of omnidirectionality one must get it up in the air and away from metallic obstructions, although people, trees, etc. will act as great sinks for RF.
Will your radio work acceptably for trail riding mounted lower-damned straight. Will it work better if mounted higher, not if it gets broken off by a tree or other obstacle.
The best way to solve this issue is to petition the FCC that ownership of a Rover satifies the ITU's requirements for Amateur Radio licensing, then we will have far more options. Now that the Morse code requirements are so modest (5wpm), there are even fewer impediments to becoming licensed. The last code test I took was 20 WPM, before the loosening of the restrictions-day late and a dollar short.
Peace,
Paul
WD9HRP |
cooper
| | Posted on Friday, June 07, 2002 - 01:16 pm: |
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Holy crap Paul, where did you go to college to learn all that? My brain just collapsed just after reading the first couple of paragraphs. Thanks for the info. though. |
gp (Garrett)
| | Posted on Friday, June 07, 2002 - 01:27 pm: |
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yeah....me too. my brain just too a huge steamer!! wow. |
Paul T. Schram (Paulschram)
| | Posted on Friday, June 07, 2002 - 01:40 pm: |
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Believe it or not, I learned it all before I went to college. My dad has been a ham for almost fifty years and my house looks more like a lab than a home, in spite of the wife:-). OK, just the basement.
Almost all of what I wrote above came from my amateur radio background. I dropped ham radio to go to college and was amazed at how easy the radio stuff was after I got my chemistry degree and worked as an engineer for a few years.
I credit my college success to the ham radio. How many 14 year-olds can do math in scientific notation?
Glad I was able to help.
Peace,
Paul |
Curtis N (Curtis)
| | Posted on Friday, June 07, 2002 - 02:09 pm: |
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My suggestion:
CB's are pretty bad because they carry such little power for such a low frequency. You really need some more horsepower in a CB for it to be effective at any real range. The problem is that everyone has CB's on rides so you practically have to have one. I use one that I Velcro to my dash where my radar detector sits, and use a mag mount antenna on the roof. Yup...sometimes I have to go reattach it when branches knock it over, but even then I can just pull it down if needed. Other than wheeling in groups, it stays out of my rig entirely or buried in my recovery kit.
I would not reccomend permanenty mounting a CB in a rig since they are of little practical use and just get in the way. The best solution is to go get your FCC Technicician Amatuer Licenses and buy a decent dual band radio. The test is easy, fast, and cheap. Permanently mount the radio because they are incredibly useful. It is hard to go anywhere that you cannot hit a repeater and summon help or assistance.
On a recent 4x4 trip, I was talking to another Rover on another trip as far as 40 miles away with no repeater. Clear as a bell!
Curtis
KD7MMK |
Paul T. Schram (Paulschram)
| | Posted on Friday, June 07, 2002 - 03:39 pm: |
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Curtis:
With apologies to Brian Bonner, YOU ARE WRONG.
Five watts on eleven meters is enough to work the world. The new Yaesu FT-817 only puts out five watts. The SGC 2020 only puts out 5 watts. The old Yaesu FT-7 only put out ten watts. My FT-7 has worked around the world many times. With only 100 watts, I commonly speak with OZ or South Africa on my way to/from work-everyday!
The amount of power is not a real impediment to HF communications. If one picks frequencies and modes of emission carefully, one can communicate.
Go back and study up some more, or you'll never upgrade.
The reason we do not have better long-distance communications on 11 meters is due to many things, but not the power. The main reason we have poor performing CBs is due to poor antennas, the amount of congestion, and right now, atmospheric conditions are pretty bad all around-damned sun! The use of Amplitude Modulation, versus suppressed sideband also limits the effectiveness. While I'm not suggesting that our CBs are comparable to a spark gap rig, they are pretty old technology.
While I support everyone obtaining their amateur radio license, it is not the answer for everyone as some don't have the time (or willingness to make the time-Perrone!) or aren't willing to make the commitment to learn the 5-wpm code. Also, in many cases, the equipment is far more expensive, just like Rovers.
I'll get off my soapbox now.
Paul |
cooper
| | Posted on Friday, June 07, 2002 - 03:41 pm: |
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UMM, so do i need to take back the CB Radio i got back to Radio Shack? After hearing all this, my little 70 dollar CB Radio i got seems pretty worthless. I'm assuming you have to have a license to buy a dual band radio and an FCC Tech Amatuer License. Since i probably dont have time to do this, whats the next best thing. I have already mounted the antenna to the ARB and it actually looks pretty sweet to me and is out of Mr. Pine and Mr. Oaks way. So, i'm back to the radio now.
For Paul and Curtis, what kind do ya'll have? (Ya'll, i'm from the south) |
Ho Chung (Ho)
| | Posted on Friday, June 07, 2002 - 04:31 pm: |
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nah, just keep the CB. and consider getting the fancy stuff as an addition to the CB.
CB is what is mostly used on trail rides anyways. |
Axel Haakonsen (Axel)
| | Posted on Friday, June 07, 2002 - 04:58 pm: |
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And CB's are not just useful on the trail. I keep one permanently in both the Disco and the Freelander. When you travel on the Interstate, the absolute best way to figure out where the speed traps are, what road conditions are etc, is good old CB channel 19. As long as there are truckers around, channel 19 will outperform a radar detector any day. |
Al Oliveira (Offroaddisco)
| | Posted on Friday, June 07, 2002 - 05:14 pm: |
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Also... alternatives to CB...
Ham... no you don't need to learn 5wpm code anymore but everyone you talk to has to be tested and licensed.
MURS... (151 and 154 MHz) cheap VHF no license service but since it's so new almost no one uses it (yet).
FRS... (462Mhz) uh... it's okay but it's also a toy. 1/2 watt power output and no external antenna can be used but widely adopted.
GMRS... (462 and 467 MHz) you can talk to FRS users and use repeaters. UHF frequency gives you the use of small 6" 1/4 wave antennas. Hand helds can use external antennas and mobiles can use up to 50 watts of power (not that power is all that important). I think this srvice is very much like the UHF CB service in Austrailia. Most if not all communication on GMRS and FRS is in FM not AM like the US CB. You need to pay $75 for a license that covers your entire family but you can still talk to FRS users on your GMRS radio. GMRS radios tend to be more expensive and of commercial Mil-spec quality but this is changing.
CB... (27MHz) er... pop in that 8-track. 1/4 wave CB antenna is 102" making it a poor frequency for mobile use and even worse for hand held use. Cheap radios are very available.
I personally use CB and GMRS. I do have some MURS radios but they are of limited use right now. With the GMRS radios I keep a couple of hand helds in the truck along with my ICOM IC-F2020 mobile. When I have to get out of the vehicle I can carry one of the hand helds and still talk to eveyone in the group. One drawback for UHF is that it can't go around hills very well but it does a better job than CB of getting the signal out of your vehicle or building. |
Al Oliveira (Offroaddisco)
| | Posted on Friday, June 07, 2002 - 05:21 pm: |
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Third, the ground plane is not affected by the placement of the antenna. A ground at RF is more concerned with having things bonded to the same ground potential. It should be symmetrical around the base of the antenna...
Actually Paul you proved my point about mounting on the roof over mounting on the bumper. The roof will provide more symmetry than a bumper. This is one reason why fenders and bumpers are not a good location. A trunk or roof is much better. In our vehicles a trunk is not an option but the roof is. But since installing a 24"-102" antenna on a roof of a 7'+ vehicle is not practical, bumper mounts will generally work. Next time you're behind a police car take a look at where the antennas are mounted. In most cases they will either be mounted on the trunk or roof. I have only see a few cases where the antenna was mounted on the fender. |
Axel Haakonsen (Axel)
| | Posted on Friday, June 07, 2002 - 06:54 pm: |
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I have my antenna mounted in the middle of the roof. I use a short whip when on the trail, and a 5 footer on the highway. I have quick disconnects on them, so I can swap them in a couple of seconds. Works like a charm. |
cooper
| | Posted on Friday, June 07, 2002 - 08:33 pm: |
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I'll take some pictures of how it's mounted and send them and you can tell me what you think.
As for the CB, it's a Radio SHack CB. It was on sale so i bought it. It's small and compact was the other reason, very easy to mount. There's no where to mount the bigger ones, they were huge and the only difference was that they had a compass and a weather radio. I dont need that. The little one had the same talking ability as the bigger one.
Now, there are Cobra's and Midlands and other nicer more expensive one's but are they more capable. Can i talk and receive from a greater distance because of their name? They seem to have the same capabilities. Am i wrong? |
Axel Haakonsen (Axel)
| | Posted on Friday, June 07, 2002 - 09:20 pm: |
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Cobra's and Midlands more capable than a Radio Shack CB? It depends on how you define capable. I think it has more to do with build quality and durability. The more expensive units will also have features like noise reduction and so on. Like the saying goes, you get what you pay for. Will the little Radio Shack radio do the job on the trail? Sure. Will it do it 5 years from now, after being bounced around, exposed to heat, dust etc? Maybe, maybe not. But who cares, if you got a good price and it does the job for you, that's what matters. If it stops working, throw it out and get another one. |
Curtis N (Curtis)
| | Posted on Friday, June 07, 2002 - 11:12 pm: |
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Paul,
While I agree with you on most of your points, you only went to prove (fogive me Brian Bonner?) that I AM RIGHT and this must mean that YOU ARE WRONG 
You spake:
"The amount of power is not a real impediment to HF communications. If one picks frequencies and modes of emission carefully, one can communicate."
Uh huh. Try this with an improper antenna, one of 40 channels chosen by one other than yourself, cheap circuitry, and deep in a canyon. Go back and read my post. We are talking CB...not quite 11M. We are also talking about QSLs in many circumstances, and not standing on a mountaintop with a nice, big high pressure system overhead.
Then you babbled:
"Go back and study up some more, or you'll never upgrade."
Paul, this is the silliest assumption I have heard today. What in the world makes you think I want to upgrade? I don't get it. FTR - I have no intention of upgrading. My radios are for emergency and fun. I do not have the time or inclination to do HF.
However, I will reiterate that my above opinion that a CB would be more effective with more power is true and for you to say it is not is goofy .
Curtis |
Paul T. Schram (Paulschram)
| | Posted on Monday, June 10, 2002 - 10:57 am: |
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Curtis:
The wavelength of the CB channels is 11 meters.
Yet another example of what happened when they lowered and eliminated the morse code requirement.
Also, go reread your comments about power. I was only referring to the power not being the controlling component here. With a good antenna and good atmospheric conditions, extreme long distance communications are indeed capable of being conducted on CB frequencies. Back before it was taken from the hams, it was a very popular frequency for long distance communications. |
Curtis N (Curtis)
| | Posted on Monday, June 10, 2002 - 03:42 pm: |
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Paul,
You are correct. My post should have read 10M. But please, tell me how this would be an example of "what happened when they lowered and eliminated the morse code requirement"? The test I took certainly did cover frequencies and thier uses.
I am sure your knowledge of the topic at hand is much better than mine. However, you have still said nothing that makes me think that a CB would not operate better under adverse conditions with more power.
Regardless of what 11M may have been, it is regulated now as a CB freq. I am sure you know the wattage limitation. IMO this has cripled what could be done on 11M, but I am sure you will say something to prove me wrong
Curtis |
Paul T. Schram (Paulschram)
| | Posted on Monday, June 10, 2002 - 04:43 pm: |
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Curtis:
There are many hams who are doing wonderful things with extremely low power levels, even on 160 meters. Under adverse conditions, digital forms of communications are our best means of communicating-ie. PSK-31 or CW.
Again, one does not need high power levels to effectively communicate.
I definitely agree with you that the majority of the problem with CB is the method of modulation and the incredible amounts of QRM, but, it just sounds like 75 meters on the weekend. See, I don't disagree with all of your statements Curtis! I wish I knew how to do the cute little smiley face:-).
It is far too common for folks trying to improve their radio's efficiency to attempt to do so by adding watts, when in most, if not all cases, the antenna would allow for greater signal strength improvement. When one does the necessary math, one will learn that it takes incredible increases in power to gain even a single S-unit improvement.
Again, 15 meters and 10 meters are great DX bands, so why isn't CB? Other than the fact that communicating over distances greater than five miles are illegal (or used to be-I admittedly do not keep abreast of 11 meter regulations), there is no reason why one could not conduct trans-oceanic communications on CB frequencies, using CB equipment and power outputs, in fact, it used to be very common to convert CB rigs to 10 meters. The 10-10 group used to have nets where they encouraged only folks who had such radios to congregate.
Hope to see you on the trail or the air.
peace,
Paul |
Curtis N (Curtis)
| | Posted on Monday, June 10, 2002 - 06:07 pm: |
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Paul,
I think we are pretty much saying the same thing from two different side of the room I agree that 11M would be a good freq to use for long distance comms. The problem is more complicated though. It is almost impossible to optimize a CB antenna on the trail. Antennas cannot be mounted in just the right place, you are talking to people with less then desirable set-ups, and you are communicating in obstructed terrain. This leads to people not being able to communicate further than they can usually yell.
I guess my solution would be more power and in this regard you are very correct. FCC says you can�t go over 4.5W so this solution is useless. The best solution is to make the best out of what you have and optimize your antenna�or get your license.
Under the most difficult circumstances I use my TM-D700A on 2M with great success. Sure, I have to keep the damned CB around, but still � it s a worthless box when it comes to summoning help. Even in the most remote areas of the West I can listen to chatter on 2M repeaters. If I need help � I can probably reach it.
It is also worth noting to any unlicensed readers that you do not need an Amateur license to own a radio or to listen to it, only to communicate under normal conditions. If an emergency occurs involving the jeopardy of life or property, you may transmit on any frequency at whatever power is necessary to summon help. For those that like deep explorations in the bush this is essential knowledge.
Cheers,
Curtis |
Paul T. Schram (Paulschram)
| | Posted on Monday, June 10, 2002 - 06:08 pm: |
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Well put. See you on the trail and the air |
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