ecps92
Member
Tunable means - You cut to the Length you need (ie: Tune it) - remember tho you can't go back 
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Antenna choice for business band and Amatuer band
- Thread starter kixntuff
- Start date
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Project25_MASTR
Millennial Graying OBT Guy
He got $38,000 for the 3/4 ton he traded last February. I got $19,000 for the 1 ton with a blown motor I traded off 2 years ago. The half ton that replaced it cost more new (2014) than the 1 ton did in 2006 and gets 4 mpg worse fuel mileage.
I understand his irrational fear...I just said F-it and stopped caring about mine.
I have a chrome mount just like those shown in the link you supplied. I know a few on this thread aren't keen on mag mounts, but I find they work well. They hold nice and firm.
As far as the connector is concerned.. Get the one that will screw into the back of whatever radio you choose.
I have four vehicles. One has a VHF/UHF antenna mounted on the trunk using a proper trunk mount. But, I can't afford to buy a radio and antenna for my other two cars and my truck. So I have one radio that I carry between the vehicles and just leave it sitting on the seat. I feed that to the mag mount that I plunk in the middle of the roof. (Which is the optimal placement).
The only downside to mag mounts is running the coax. I slam it in the rear passenger door For me it's not that bad because I rarely carry passengers. But if you do carry passengers a lot, the door slamming can be hard on the coax.
mmckenna
I ♥ Ø
Good choice. I've had one of those for many years. I don't use it anymore, but it's been used well. Larsen is a good name and well backed up.
Likely you don't need the spring. The whip on this antenna is pretty flexible on it's own. Unless you expected hitting really low tree branches or parking garages, I'd skip it. Springs can -sometimes- introduce some unwanted noises.
You should get whatever connector matches the back of your radio. Since we don't know what radio you are going to use, we can't answer for you.
The only real choice here is this one:
Get what matches your radio
or,
Get the FME connector and then the adapter to match your radio. While I'm usually against adapters for any sort of permanent install, the FME is specifically designed to be small diameter to pass through holes without needing to remove the connector. You then simply screw on the adapter that fits your radio. One of the few places where using an adapter can make sense.
Since this is a magnetic mount, you won't be trying to snake the pre-terminated cable through a hole, so this shouldn't be an issue. Therefore, I'd suggest just getting the right one that matches your radio. Any adapters will be problematic. They put a lot of stress on the antenna connector on the back of the radio and can easily damage it, especially in high vibration environments.
Yes, you will need to cut it. The frequency range has more to do with the base coil and the overall frequency range. You'll need to trim it to work right on the frequencies you are licensed for. To do that it's best to find the center of the frequency range you'll be using and cut for that. The cutting charts usually only go down to 1 or 2 MHz of resolution, so you don't need to be exact.
Example:
If one frequency was 151.000MHz and the other was 156.00MHz, you'd want to cut the antenna for 153.000MHz.
In the mountains a 1/4 wave antenna is the thing to have. A 1/4 wave can "see" in more directions than a 1/2 wave can. A 1/2 wave has a narrower view, which would be better for flat lands.
1/4 wave is the most compact and versatile.
I like the Tram 1185 for a mag mount. If you can go with a permanent mount such as nmo, go with one. A nmo mount with a large area of metal underneath it.
kixntuff
Member
Yeah,
I'm leaning more toward a 1/4 wave now. I figured that if I have to hit weatherman flying in an airplane or hit him on top of Mt. Diablo sitting at 10,000 feet, I better go with a 1/4 wave. So this leads me to a few more questions.
1. When the antenna says that it is only good for 144 to 174Mhz, could I still dial up my buddy 200 yards away by the race course using a Midland GMRS hand held radio on one of the GMRS channels which I think is around say 462.550Mhz. Will I be able to communicate with him?
2. I noticed that some of the VHF radio connections for some radios are PL-259, and when you go to buy an antenna with this already mounted it calls it a UHF PL-259 connector. Will that connector work on a VHF radio?
3. Will this antenna http://www.theantennafarm.com/catalog/larsen-nmoqw144-722.html with it's 8Hhz bandwidth get me up to 155Mhz or is the 152Mhz it's peak counting the 8Mhz? Also Larsen is saying that this antenna doesn't need to be tuned, but Larsens Cut length list for 152Mhz is like around 18 or 19 inches and this Antenna is 21" long. What's up with that?
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mmckenna
I ♥ Ø
Depends on your radio. If you have a dual band radio, then yes, you could, but there are a few issues:
1. You would need a valid FCC issued GMRS license to do this in the USA. Not sure what you'd need to do it legally in Mexico.
2. A 1/4 wave VHF antenna acts as a 3/4 wave UHF antenna on the UHF frequencies (GMRS/FRS/70cm amateur). It's not quite as wide a bandwidth, so you'd have to be really careful and make sure the antenna was somewhat resonate on the UHF frequency. I've used VHF quarter wave antennas on dual band amateur radios with good results, but it was limited to 144-148/440-450MHz.
3. There are some tricks to setting up a commercial radio to work well with consumer grade GMRS/FRS radios. Not impossible....
Yeah, that gets a bit confusing.
Some of the terminology for the antenna connectors is problematic.
"UHF" connectors are often used for 2 way radios. It doesn't mean it's limited to UHF radios, it's just the type of connector.
UHF connector is the same as a SO-239 (socket) and PL-259 (plug). Just different terminology.
Many VHF mobile radios have a UHF type connector. A few of the brands might be different. Just get the right one to match your radio and you'll be OK.
The issue is UHF = Ultra High Frequency. Back when this connector was developed, VHF (Very High Frequency) was considered "Ultra High". As technology progressed the connector name didn't keep up.
I wish the industry/hobby/manufacturers would stop using the UHF connector term and stop using the UHF connector all together.
It'll work fine. The claimed bandwidth really depends on exactly how you are measuring it. That antenna will work just fine for use on the 2 meter amateur radio band AND the 151-155MHz frequencies you will be using. Just tune/cut it for somewhere around 150MHz and it'll work fine.
That specific antenna is cut for 148MHz, and it's saying that it'll work fine between 144MHz and 152MHz. Your radio/antenna will do just fine up to 155MHz and probably farther.
I'm going to see if I can pull the plot of my analyzer to show what the VHF quarter wave antenna looks like in the way of bandwidth. If I can get it off the machine, I'll post it here.
ecps92
Member
To use FRS/GMRS Frequencies in Mexico, make sure the radio is Certified with the Mexican Authorities, just like our FCC and Industry Canada
Mexico's Family Radio Service (FRS) equivalent
https://en.wikipedia.org/wiki/Family_Radio_Service#Mexico
Mexico's Family Radio Service (FRS) equivalent
https://en.wikipedia.org/wiki/Family_Radio_Service#Mexico
mmckenna
I ♥ Ø
OK, here's the plot from a quarter wave VHF antenna. NMO permanent mount in the dead center of a pickup truck roof. Ideal install for a mobile antenna.
This one is on my work truck. It's specifically cut/tuned for some VHF repeaters I have around 158MHz. The lowest SWR on the antenna is at 159.000MHz a 1.16:1.
144.000MHz, the bottom of the Amateur 2 meter band shows 1.69:1, well within the acceptable range for a mobile antenna. Not ideal for -just- amateur use, but acceptable considering the antenna is intended/cut for use on my work repeaters.
Even looking at the very high end of the VHF LMR band, well into "federal" frequencies, it's still showing 1.74:1, acceptable...
It's really hard to beat a quarter wave.
This is the same antenna you linked to above. Cutting it a bit longer will bring the lowest SWR down closer to the 151 range and will lower the SWR across the 2 meter band.
This one is on my work truck. It's specifically cut/tuned for some VHF repeaters I have around 158MHz. The lowest SWR on the antenna is at 159.000MHz a 1.16:1.
144.000MHz, the bottom of the Amateur 2 meter band shows 1.69:1, well within the acceptable range for a mobile antenna. Not ideal for -just- amateur use, but acceptable considering the antenna is intended/cut for use on my work repeaters.
Even looking at the very high end of the VHF LMR band, well into "federal" frequencies, it's still showing 1.74:1, acceptable...
It's really hard to beat a quarter wave.
This is the same antenna you linked to above. Cutting it a bit longer will bring the lowest SWR down closer to the 151 range and will lower the SWR across the 2 meter band.
mmckenna
I ♥ Ø
OK, not to confuse things, but here's a plot from a 1/2 wave VHF antenna mounted on the rear of the roll cage of a 2010 Polaris Ranger UTV.
The machine was set up a bit different, so the numbers don't match up the 1/4 wave plot above, but you can get the idea. The 1/2 wave antennas are narrower bandwidth. They do offer some more gain if you give them some ground plane to work with. The rear of the roll cage on my UTV isn't ideal. It's also tuned for the center of the amateur radio 2 meter band, where we usually talk between UTV's when we ride (everyone I ride with has their amateur radio license). I do have some commercial stuff in that radio, so I was checking the performance on those frequencies.
Anyway, what I'm getting at here is that as you increase the gain, you lose usable bandwidth. You can see from this plot that the "dip" is narrower than the 1/4 wave above:
The analyzer was set up for showing return loss instead of SWR like the plot above.
A quick and dirty conversion will show that:
at 146.121MHz 40.11dB equals right about 1.02:1 SWR.
Out at 153.630MHz 16.85dB equals 1.336:1 SWR
So, still good, but not quite as good. The trade off is that the 1/2 wave antenna probably is showing a bit more gain.
The machine was set up a bit different, so the numbers don't match up the 1/4 wave plot above, but you can get the idea. The 1/2 wave antennas are narrower bandwidth. They do offer some more gain if you give them some ground plane to work with. The rear of the roll cage on my UTV isn't ideal. It's also tuned for the center of the amateur radio 2 meter band, where we usually talk between UTV's when we ride (everyone I ride with has their amateur radio license). I do have some commercial stuff in that radio, so I was checking the performance on those frequencies.
Anyway, what I'm getting at here is that as you increase the gain, you lose usable bandwidth. You can see from this plot that the "dip" is narrower than the 1/4 wave above:
The analyzer was set up for showing return loss instead of SWR like the plot above.
A quick and dirty conversion will show that:
at 146.121MHz 40.11dB equals right about 1.02:1 SWR.
Out at 153.630MHz 16.85dB equals 1.336:1 SWR
So, still good, but not quite as good. The trade off is that the 1/2 wave antenna probably is showing a bit more gain.
kixntuff
Member
OK, not to confuse things, but here's a plot from a 1/2 wave VHF antenna mounted on the rear of the roll cage of a 2010 Polaris Ranger UTV.
The machine was set up a bit different, so the numbers don't match up the 1/4 wave plot above, but you can get the idea. The 1/2 wave antennas are narrower bandwidth. They do offer some more gain if you give them some ground plane to work with. The rear of the roll cage on my UTV isn't ideal. It's also tuned for the center of the amateur radio 2 meter band, where we usually talk between UTV's when we ride (everyone I ride with has their amateur radio license). I do have some commercial stuff in that radio, so I was checking the performance on those frequencies.
Anyway, what I'm getting at here is that as you increase the gain, you lose usable bandwidth. You can see from this plot that the "dip" is narrower than the 1/4 wave above:
The analyzer was set up for showing return loss instead of SWR like the plot above.
A quick and dirty conversion will show that:
at 146.121MHz 40.11dB equals right about 1.02:1 SWR.
Out at 153.630MHz 16.85dB equals 1.336:1 SWR
So, still good, but not quite as good. The trade off is that the 1/2 wave antenna probably is showing a bit more gain.
But in my case, more gain may not necessarily get me up to weatherman in an airplane or on top of a mountain with the wrong wave antenna. Sounds like the most low risk option is to go with a 1/4 wave. So what you are saying above is that I could basically take any of those commercial 1/4 wave antennas and cut them to put into the frequency range I need regardless of what they say the range is in the description? The other Larsen antenna has the exact same length at 21" and is virtually identical to the one I posted, but it says the range is 152mhz to 162mhz. Also says no tuning needed. Costs more though. ha ha What's up with that?
mmckenna
I ♥ Ø
Sort of. The ones that are pre-cut for the higher frequencies won't work since you can't make them longer. Either get one for the right frequency, or get an uncut one and do it yourself.
People will pay more if they think it's "easy". No tuning required is something that draws a lot of people that either don't know any better or just don't have the equipment to cut and test on their own. Consumers can _always_ be tricked into paying more...
People will pay more if they think it's "easy". No tuning required is something that draws a lot of people that either don't know any better or just don't have the equipment to cut and test on their own. Consumers can _always_ be tricked into paying more...
This is what most of the racers use on VHF.
http://forums.radioreference.com/at...-4-wave-vhf-spring-without-comtelco-a1511.png
http://forums.radioreference.com/at...-4-wave-vhf-spring-without-comtelco-a1511.png
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It's hard to beat them because they are just do darn durable!
And cut it for 151 MHz. I heard that advice somewhere.
kixntuff
Member
So I called the guy at antenna farm and picked his brain about having 2 no tune antennas that were for different frequencies that were identical in all aspects including the length and how that was possible. Still don't know I understood why. Anyway, I got to talking with him about needing to tune it to 151Mhz and he turned me onto the field tunable antenna section. Found lots of 1/4 wave antennas and have it narrowed down to these 2.
1. http://www.theantennafarm.com/catalog/laird-technologies-abft-764.html Will This antenna work on this mount? http://www.theantennafarm.com/catalog/larsen-nmommrpl-1097.html
2. http://www.theantennafarm.com/catalog/larsen-nmoqb-6440.html I'm assuming that this antenna and mount would be a good combo? http://www.theantennafarm.com/catalog/larsen-nmommrpl-1097.html
1. http://www.theantennafarm.com/catalog/laird-technologies-abft-764.html Will This antenna work on this mount? http://www.theantennafarm.com/catalog/larsen-nmommrpl-1097.html
2. http://www.theantennafarm.com/catalog/larsen-nmoqb-6440.html I'm assuming that this antenna and mount would be a good combo? http://www.theantennafarm.com/catalog/larsen-nmommrpl-1097.html
mmckenna
I ♥ Ø
I've been using Larsen antennas for 25+ years now. Never had one fail. I stick with the second one, the NMOQ. It's a known good base design.
I'd recommend not getting the -B model, though. The only part of it that's different from the standard NMOQ is that there is a black coating on the whip. The NMO-Q still has the black base. I can tell you from first hand experience that the black coating will start coming off. Be it a tree branch, parking garage or even a largish bug, the coating will start to chip/flake off and the antenna starts to look like crap after a year or so. You can sort of touch it up with a black sharpie marker, but it's an ongoing process until there is no black coating left on the whip.
If you really must have a black whip, just get the chrome one and some 1/16 or so diameter black heat shrink tubing. Use a lighter or other heat source to shrink it to fit the whip. It'll last a whole lot longer and you can always shine it up with some armor-all.
The Larsen mounting base you chose is fine. I actually have a few of those at work. Had some customers that wanted to use mobile radios as a base. We mounted the mobile radio in a power supply housing and they stick the magnetic mount antenna on top of a file cabinet.
I'd recommend not getting the -B model, though. The only part of it that's different from the standard NMOQ is that there is a black coating on the whip. The NMO-Q still has the black base. I can tell you from first hand experience that the black coating will start coming off. Be it a tree branch, parking garage or even a largish bug, the coating will start to chip/flake off and the antenna starts to look like crap after a year or so. You can sort of touch it up with a black sharpie marker, but it's an ongoing process until there is no black coating left on the whip.
If you really must have a black whip, just get the chrome one and some 1/16 or so diameter black heat shrink tubing. Use a lighter or other heat source to shrink it to fit the whip. It'll last a whole lot longer and you can always shine it up with some armor-all.
The Larsen mounting base you chose is fine. I actually have a few of those at work. Had some customers that wanted to use mobile radios as a base. We mounted the mobile radio in a power supply housing and they stick the magnetic mount antenna on top of a file cabinet.
kixntuff
Member
Awesome! Thanks for the info on that. I definitely do not want to be up there touching it up all the time. So all this antenna tuning has got me thinking about my hand held antenna for my Baofeng UV-82hp. The Antenna I chose was a Nagoya 771 as shown here Amazon.com: Genuine Hypario HPA-771 (Updated) sma Female 15.5" Dual Band Antenna (144/430Mhz) Pofung - BaoFeng, Kenwood, Wouxun Compatible (including UV-82, UV-5R, BF-F8HP, GT-3, BF-F8+, 888s Series): Car Electronics. Would this antenna perform as good as an antenna tunned closer to the band I will be transmitting on for BAJA 150Mhz through 154Mhz? Something say like this http://www.theantennafarm.com/catalog/larsen-spwb24150-6908.html ? It's a 150Mhz to 162Mhz.
Rubber attenuators... oh sorry, antennas... are usually about equally dismal. There may be a difference in radiated field strength, but that will come down to a test of which antenna produces the best readings when tested with a field strength meter. Receive performance is likely to be the same (and tougher to test accurately). You'll need to acquire or pay someone to acquire both antennas and a VHF field strength meter. Or start a new thread here on RR asking if someone will do it for fun / free. I'll do the test, but you'll need to send me the Larsen SPWB24150. I already have an NA-771 and FSM. Or just wait awhile and keep reading this thread. You are likely to get a few WAGs and unqualified opinions about which antenna is better.
K5MPH
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I have use the Larson NMOQB with a mag mount for years and has always worked good for me,this antenna is very broad banded,just remember that the 1/4 wav is more wide banded the 5/8 wave will give you more gain and range,good luck on your project.......
kg4wbb
Member
I have seen a few of the Motorola commercial 440 mhz antennas at Hamfest that are about 7 elements with a dipole driven that can be loosened up and slid forward or backward to change the SWR. Has anyone had any luck in expanding the solid elements so that it will work on ham 70 cm and , if so, what did you do ? I've tried making sleeves that slip over the elements, but so far , no luck. I have considered drilling a small hole and taping it through the center of each element so that a brass screw could be screwed into it to fine tune. Is it possible to heat up the elements and stretch them out to length ? Thanks.
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