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effective dual band yagi for gmrs


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#1 scottmckinney67

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Posted 29 January 2020 - 10:58 AM

Hi guys and gals,

 

I'm looking to buy a directional antenna for GMRS that will also work on VHF when I get the tech license.  I've been looking at elk and arrow.  I love the portability but don't want to sacrifice too much performance.  Are these on par with say a cushcraft or some other brand of dual band yagi for GMRS?  Are there any specific antennas that you recommend?

 

I'm in a residential area and currently have 2 40 watt mobiles connected to midland 6dbi whips with ground plane plates.  Trying to talk simplex with my son that isn't far but we're marginal on height restrictions at his mom's house.  Right now we can talk, but it's pretty noisy and annoying. I used this calculator https://www.scadacor...-line-of-sight/ and it confirms we're on the edge height wise.  I will be able to raise his slightly, to maybe 3.5 meter height.  I'm around 8 meters high at my place in the attic.  I understand that height will trump pretty much everything but ex's rule in this case as far as my mounting at that location.

 

I'm hoping to keep antenna cost under 200.

 

Thanks!



#2 marcspaz

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Posted 29 January 2020 - 11:24 AM

Most UHF beams only have 15MHz to 20MHz of bandwidth they are usable for. You are not likely to find one that is going to cover 50MHz unless all of the elements and spacing are tunable (which I have never seen). That's more than double the typical bandwidth coverage.

#3 RCM

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Posted 29 January 2020 - 12:58 PM

First, I would forget about dual band Yagis. They tend to be a compromise at best, and most of them have minimal gain. Also if it's dual band, it won't be 2M and GMRS; it will be 2m and 440. Even if it happens to work somewhat on 462/467, it won't be ideal.

I would get a Larsen welded Yagi that is designed for 450-470 MHz, like this one: https://amzn.to/316dWOk

Those will last a very, very long time; and a pair of them pointed at each other will probably solve your problem.

Then when you get your ham license, get a dedicated antenna for that based on what you need it to do.



#4 scottmckinney67

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Posted 29 January 2020 - 01:32 PM

Thanks for the responses guys.  What about an omni 70cm/2M that would have a decent SWR on GMRS frequencies?  If I got a taller omni on my end, and could possibly raise his whip some, think that would work.  I don't plan on GMRS being our band of choice but it's what we're licensed for at this point.



#5 marcspaz

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Posted 29 January 2020 - 02:33 PM

Omni's fall into a similar issue.  While there are some dual-band 2m/70cm vertical antennas that cover from 440-470 MHz, the gain is very low.  As gain increases, the bandwidth narrows and so does the takeoff angle, impacting sensitivity between stations with elevation difference.

 

So, if you have the expendable income, you can test it.  However, don't be surprised if the lower gain of a broad band antenna doesn't help much.

 

I have to agree with RCM on getting two service-dedicated Larsen welded Yagis.  That's going to be your best bet, relating to both performance and price.


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#6 scottmckinney67

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Posted 29 January 2020 - 02:47 PM

I don't have the expendable income and don't want to buy something that will be obsolete once we get tech licenses.  I'm going to raise his antenna and go from there.  We should have just skipped GMRS in the first place and got the tech licenses.  No open repeaters that I can find in my area.  Thanks again.



#7 marcspaz

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Posted 29 January 2020 - 02:57 PM

Sorry to hear that.  I'm not sure what your goals are, but I have been a Ham for close to 18 years and GMRS is a fantastic service that I use regularly. The thing about radio service is to use the proper service for the comms you are trying to have.


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#8 scottmckinney67

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Posted 29 January 2020 - 04:34 PM

Sorry to hear that.  I'm not sure what your goals are, but I have been a Ham for close to 18 years and GMRS is a fantastic service that I use regularly. The thing about radio service is to use the proper service for the comms you are trying to have.

I thought I stated my goal earlier, maybe that wasn't clear.  Based on the advice of other ham operators, who thought this wouldn't be an issue, I bought these small antennas and cheap radios and obtained a gmrs license.  It's not a gmrs issue, it's a line of sight and lack of gmrs open repeater issue in my opinion.  If you look at the link I posted and put in some antenna heights it gives what is a usable range based on some sort of path study parameters.  We're on the hairy edge.  I understand your mileage may vary when doing this but a few miles is kicking our butts at the moment.  

 

I do appreciate the advice.  We don't give up, so one way or another, we'll make it happen.  I just spoke to my son's mom and she's ok with an omni above the roof line.  I'm going that route with standard dual band antenna that has a relatively low swr on grms and we'll make due for now.  That doesn't work, tech licenses and I already have a diamond dual band mobile that I can stick in the attic after we get the licenses.



#9 n4gix

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Posted 29 January 2020 - 05:22 PM

Good luck for whenever you take the test for tech licenses.


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#10 marcspaz

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Posted 29 January 2020 - 09:55 PM

Sorry... I misspoke.  I do realize that you have stated what your objectives are.  I guess I didn't understand why you are trying to get a multi-service beam or vertical.  After re-reading, if you are trying to get the most value per dollar, that makes sense.  Unfortunately, however, it doesn't work to our benefit very often.  Most multi-function devices accommodate convenience at the detriment of performance.

 

The map you shared is showing about 70 miles from point to point.  That is the very edge for 50 watts on a vertical.  Hopefully setting the antennas higher will do the trick.

 

Good luck with the Amateur radio test.  It opens up a whole new real of possibilities. 


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#11 shaine

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Posted 29 January 2020 - 10:25 PM

I would only opine that there is no magic that comes with a Technician license over GMRS. It's practically the same physics at play. I'm facing a different problem, but also physics related. I live in a dip that breaks LOS in the direction that I need coverage. GMRS focuses my solutions to the GMRS band, whereas the amateur solution spreads me over several bands, which equal more $

 

The only exception would be HF, which would do a better job at distance. 

 

Otherwise, I'm focused on doing GMRS really well as I can tune everything to be excellent at those frequencies. 


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#12 scottmckinney67

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Posted 29 January 2020 - 10:45 PM

Sorry... I misspoke.  I do realize that you have stated what your objectives are.  I guess I didn't understand why you are trying to get a multi-service beam or vertical.  After re-reading, if you are trying to get the most value per dollar, that makes sense.  Unfortunately, however, it doesn't work to our benefit very often.  Most multi-function devices accommodate convenience at the detriment of performance.

 

The map you shared is showing about 70 miles from point to point.  That is the very edge for 50 watts on a vertical.  Hopefully setting the antennas higher will do the trick.

 

Good luck with the Amateur radio test.  It opens up a whole new real of possibilities. 

No worries.  That map is just the link.  I'm literally less than 3.5 miles as the crow flies.  I think that's why my experienced buddies said it should be no problem.  When I place my antenna at 6 meters and my son's at 2 meters, the line shows red.  I go up to 7, it goes green.  I did get my antenna up to 8 meters high in my attic, drove to the area where my son's house is and we can talk, but the noise level is very high.  This is with the antenna on the roof of my honda accord, so probably close to 2 meters.  This is why I think the issue is terrain and elevation between us.  I bought the radios before finding that site and used the standard line of sight calculation and thought it would be no problem.  So I think even an antenna that's not exactly resonant on GMRS but close with a decent SWR a few meters off the ground will do the trick on his end.  Make sense?  I was looking at the yagi on his end to aim at me originally, but figured in the long haul, a comet, diamond, tran, omni would be a good choice since we plan on getting tech licenses.



#13 scottmckinney67

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Posted 29 January 2020 - 10:46 PM

Good luck for whenever you take the test for tech licenses.

Thank you.



#14 scottmckinney67

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Posted 29 January 2020 - 10:48 PM

I would only opine that there is no magic that comes with a Technician license over GMRS. It's practically the same physics at play. I'm facing a different problem, but also physics related. I live in a dip that breaks LOS in the direction that I need coverage. GMRS focuses my solutions to the GMRS band, whereas the amateur solution spreads me over several bands, which equal more $

 

The only exception would be HF, which would do a better job at distance. 

 

Otherwise, I'm focused on doing GMRS really well as I can tune everything to be excellent at those frequencies. 

 

A tech license opens up some repeaters in my town.  Apparently there aren't any in Columbus Ohio, or the owners won't allow me.  I've asked and no response.



#15 marcspaz

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Posted 29 January 2020 - 11:06 PM

Ah... I see what you are saying. Hmmm. So that distance shouldn't be too bad with a shade more height on his end. If mom is willing to have the antenna higher than the rooflines, then you should be good.

On the SWR side, there are some antennas that might be close. While high SWR means loss of radiated power... if you stay below 3:1, in theory nothing should break. I had run 180 watts pep on a setup that was 2.4:1 for 2 years, before I fixed the HF antenna. If you are going to throw the dice, try to find something that will be 2:1 or better.

Companies like Diamond offer antennas that are mostly fixed, with a small adjustable whip section. You can buy a base antenna and two adjustable whips. Cut one to GMRS and the other to Ham 440 band. Then you can just swap the inexpensive whip around depending on the service you want to use.

I haven't tried it at home, but I use that MO on my CR8900 on the Jeep. It works pretty well.

#16 scottmckinney67

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Posted 29 January 2020 - 11:29 PM

Ah... I see what you are saying. Hmmm. So that distance shouldn't be too bad with a shade more height on his end. If mom is willing to have the antenna higher than the rooflines, then you should be good.

On the SWR side, there are some antennas that might be close. While high SWR means loss of radiated power... if you stay below 3:1, in theory nothing should break. I had run 180 watts pep on a setup that was 2.4:1 for 2 years, before I fixed the HF antenna. If you are going to throw the dice, try to find something that will be 2:1 or better.

Companies like Diamond offer antennas that are mostly fixed, with a small adjustable whip section. You can buy a base antenna and two adjustable whips. Cut one to GMRS and the other to Ham 440 band. Then you can just swap the inexpensive whip around depending on the service you want to use.

I haven't tried it at home, but I use that MO on my CR8900 on the Jeep. It works pretty well.

That's what I'm talking about!  I'd like to keep the antenna at 10 feet or less and I'll use fence top rail for a mast to clear the roofline.  I'd like to get a quality antenna that I can tune, then tune back after we get our licenses.  Any recommendations?  Also, if I drive the fence top rail 4 feet in the ground, would I need a separate ground rod?  I'm sure it's not up to code in some areas, but I don't want to start tying into her electric boxes or mess with her ground rod.  I have enough issues with her without being blamed for blowing her electric service :)  I would use a lightning arrester.  



#17 Jones

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Posted 29 January 2020 - 11:45 PM

You should be able to get full-scale copy at 3.5 miles on less than 2 watts.  If you can't do it at 40 Watts, then lose those junk Midland antennas, and get a couple of decent UHF omni antennas mounted on the roofline.  Also run a heavy, large gauge coax cable designed for UHF...such as LMR-400.  If you have those Midlands with that thin RG-174 type coax, then that is exactly why you can't get 3 miles.  If you need to extend the coax, note that the CB coax extenders you buy at the truck stop will not work at UHF.


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#18 scottmckinney67

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Posted 29 January 2020 - 11:59 PM

You should be able to get full-scale copy at 3.5 miles on less than 2 watts.  If you can't do it at 40 Watts, then lose those junk Midland antennas, and get a couple of decent UHF omni antennas mounted on the roofline.  Also run a heavy, large gauge coax cable designed for UHF...such as LMR-400.  If you have those Midlands with that thin RG-174 type coax, then that is exactly why you can't get 3 miles.  If you need to extend the coax, note that the CB coax extenders you buy at the truck stop will not work at UHF.

Thanks.  I am using the crap midlands with the light cable.  I could go with an omni uhf antenna but want one that will cover more than just gmrs as I don't ever want to not have a repeater option.  There are plenty of UHF repeaters in my area and no gmrs repeaters.  Go figure.



#19 Jones

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Posted 30 January 2020 - 12:06 AM

Thanks.  I am using the crap midlands with the light cable.  I could go with an omni uhf antenna but want one that will cover more than just gmrs as I don't ever want to not have a repeater option.  There are plenty of UHF repeaters in my area and no gmrs repeaters.  Go figure.

Well, it won't cover 2 Meters, but if you want a good wide-band UHF antenna that will not be obtrusive, and very nicely cover both GMRS and the UHF 70cm ham band, then consider a quarter-wave on one of those Laird Ground plane kits that are being discussed in this forum on another thread.  (I'll post the link shortly) - now is shortly - https://www.theanten...logies-mbc-1649

 

Quarter-wave antennas have no gain, but they do have extremely wide bandwidth, and better coverage in hilly terrain.  Since the antenna is very small and unobtrusive, you could mount it up higher on the top of the roof.  The added height, and a good coax will certainly beat what you've got running right now.



#20 scottmckinney67

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Posted 30 January 2020 - 06:51 AM

You should be able to get full-scale copy at 3.5 miles on less than 2 watts.  If you can't do it at 40 Watts, then lose those junk Midland antennas, and get a couple of decent UHF omni antennas mounted on the roofline.  Also run a heavy, large gauge coax cable designed for UHF...such as LMR-400.  If you have those Midlands with that thin RG-174 type coax, then that is exactly why you can't get 3 miles.  If you need to extend the coax, note that the CB coax extenders you buy at the truck stop will not work at UHF.

 

I'm sure that your theory is valid, thanks.  But I think this map https://www.scadacor...-line-of-sight/ program is my core issue.  When I plug in my location and my son's I get red with my antenna less than 7 meters and his less than 2 meters tall.  I located my antenna in the attic at a little over 8 meters high on a 15 inch pizza pan for a ground plane.  When I test I'm in a honda accord with the antenna on the roof, which is probably very close to 2 meters high.  We can hear each other and understand most of what's said but it's noisy and can get garbled at times.

 

I'm going to get his antenna off the ground by a couple more meters first thing.  If that gets improvement, but not enough, I'll get him a taller antenna (still undecided on what) and better cabling.

 

My plan is to get our tech licenses and then broadcast vhf or uhf to a local repeater, which I can easily hit with my ladder line antenna and my baofeng.  So, knowing that, I'm trying to upgrade his antenna once, and not buy a GMRS specific base antenna.  Looks like Trams are tunable, but not sure about others at this point.  I originally had looked at elk and arrow because they seem to be pretty wide band and are directional.  I figured with those, I may be able to get away with one antenna buy for him.

 

Stay tuned for new results and keep the comments coming guys, I appreciate the help.

 

I am disappointed that there don't seem to be any open repeaters in Columbus Ohio.  When I checked the repeater section here, it showed 2.  Both say private only and one says its down.






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