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effective dual band yagi for gmrs


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#21 marcspaz

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Posted 30 January 2020 - 08:43 AM

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.  

 

Grounding rods are typically 6 feet deep and copper.  For proper protection, you would want to ground the mast and the cable at the mast side, and as close to the radio as possible, with the ground wire being as short as possible.  Use clamps for everything; don't solder.  Lightning will melt solder joints.  During times of the year when lightning occurs in any given operating area, most people disconnect the cables when the radio is not in service.  Proper grounding still doesn't fully arrest direct or near-direct strikes.

 

As far as antennas go, if you are looking at 2m/70cm/GMRS specifically, I have a Diamond X50a on my house.  It has a 1.8:1 SWR on 462 MHz and a 1.6:1 SWR in 467 MHz.  Those are your baseline frequencies for GMRS simplex and repeaters (respectively).  Those are about $100 each.

 

There is another Diamond that could work... but I have zero experience with it and I don't know anyone who has used one.  Keep in mind, multipurpose tools like an all-bander antenna will work, but there will be a compromise on performance compared to dedicated antennas. That said, there is a Diamond Super Discone (like the D130J) that are somewhat of an all-bander antenna, for about $100 each.  For the D130J, specifically, on VHF and UHF its rated for 200 watts.  Below 144MHz, its only rated for 20 watts on FM and 50 watts on SSB.

 

You would want to either buy or borrow and antenna analyzer to dial it in.  Also, order some quality coax cable. 



#22 scottmckinney67

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Posted 30 January 2020 - 08:55 AM

Grounding rods are typically 6 feet deep and copper.  For proper protection, you would want to ground the mast and the cable at the mast side, and as close to the radio as possible, with the ground wire being as short as possible.  Use clamps for everything; don't solder.  Lightning will melt solder joints.  During times of the year when lightning occurs in any given operating area, most people disconnect the cables when the radio is not in service.  Proper grounding still doesn't fully arrest direct or near-direct strikes.

 

As far as antennas go, if you are looking at 2m/70cm/GMRS specifically, I have a Diamond X50a on my house.  It has a 1.8:1 SWR on 462 MHz and a 1.6:1 SWR in 467 MHz.  Those are your baseline frequencies for GMRS simplex and repeaters (respectively).  Those are about $100 each.

 

There is another Diamond that could work... but I have zero experience with it and I don't know anyone who has used one.  Keep in mind, multipurpose tools like an all-bander antenna will work, but there will be a compromise on performance compared to dedicated antennas. That said, there is a Diamond Super Discone (like the D130J) that are somewhat of an all-bander antenna, for about $100 each.  For the D130J, specifically, on VHF and UHF its rated for 200 watts.  Below 144MHz, its only rated for 20 watts on FM and 50 watts on SSB.

 

You would want to either buy or borrow and antenna analyzer to dial it in.  Also, order some quality coax cable. 

 

I did buy an analyzer, its the AURSINC Vector Network Analyzer 10KHz -1.5GMHz HF VHF UHF.  Do you know of any videos of how to tune the diamond x50a?  I assume that I'd cut the 70cm section slightly?  Cut radials also?  With the SWR that low, I'd think I'm safe for not blowing up my radio, I may buy that and give it a try as is.  The added height may be all that I need...



#23 marcspaz

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Posted 30 January 2020 - 09:03 AM

...lose those junk Midland antennas...

 

I have no idea how, but I have talked to a couple of people using the Midland 6db gain antennas on the mag mount, stuck to cookie sheets and they sound great.  I have never gotten that to work with any service.

 

I am using Comet and Diamond antennas for most of my mobiles.  I only have one Midland antenna left, and its going bye-bye very soon.

 

While the midland antenna seems to work okay for me RF performance wise, after less than a year, 2 of the 3 I have broke mechanically.  One, the bottom section snapped off, requiring the antenna to be re-soldered and glued back together (ended up in the trash later anyway).  A second one, the center loading coil broke in half and the top section of the antenna disappeared while cruising down the highway.  The last one I have left has only seen about 2,000 miles in the wind and it looks like a boomerang.  The metal whip sections are not standing up to highway speed winds.

 

So, yea... they are junk.



#24 marcspaz

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Posted 30 January 2020 - 09:06 AM

I did buy an analyzer, its the AURSINC Vector Network Analyzer 10KHz -1.5GMHz HF VHF UHF.  Do you know of any videos of how to tune the diamond x50a?  I assume that I'd cut the 70cm section slightly?  Cut radials also?  With the SWR that low, I'd think I'm safe for not blowing up my radio, I may buy that and give it a try as is.  The added height may be all that I need...

 

The X50a is pre-tuned.  There is nothing to adjust.  For me it just worked well for GMRS as well as 2m and 440. 

 

The CR8900's are mobile... which I did tune manually.  I would avoid trying to use them at home, though.



#25 Radioguy7268

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Posted 30 January 2020 - 09:32 AM

IMHO - you don't have an antenna problem. You've got a radio problem. 3.5 miles with 40 watts in relatively flat terrain in mid Ohio is not a line of sight problem.

 

Those Midlands are quite honestly garbage. You are going to spend a lot of time (and money) trying to make those units perform like actual radios should. Go buy some used Kenwood/Motorola/Vertex radios programmed to GMRS (which will end up costing half as much and work three times better).


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#26 scottmckinney67

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Posted 30 January 2020 - 09:47 AM

IMHO - you don't have an antenna problem. You've got a radio problem. 3.5 miles with 40 watts in relatively flat terrain in mid Ohio is not a line of sight problem.

 

Those Midlands are quite honestly garbage. You are going to spend a lot of time (and money) trying to make those units perform like actual radios should. Go buy some used Kenwood/Motorola/Vertex radios programmed to GMRS (which will end up costing half as much and work three times better).

 

I understand that my radios aren't all that, especially when it comes to receive sensitivity, but that line of sight app link that I posted contradicts that it's solely a radio problem.  I do appreciate the feedback, and I will get better radios at some point.



#27 marcspaz

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Posted 30 January 2020 - 09:59 AM

IMHO - you don't have an antenna problem. You've got a radio problem. 3.5 miles with 40 watts in relatively flat terrain in mid Ohio is not a line of sight problem.

 

Those Midlands are quite honestly garbage. You are going to spend a lot of time (and money) trying to make those units perform like actual radios should. Go buy some used Kenwood/Motorola/Vertex radios programmed to GMRS (which will end up costing half as much and work three times better).

 

Kenwood and Moto are good... but Vertex Standard?  On their own, under Moto or Yaesu, I was never a fan.  I still have one of their tuners and its better at creating RFI than a proper LC network.  LOL

 

He is using a Midland mobile mag mount antenna in the house.  Regardless of the radio in use, I am fairly confident the lack of a proper antenna is an issue.



#28 marcspaz

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Posted 30 January 2020 - 10:05 AM

I understand that my radios aren't all that, especially when it comes to receive sensitivity, but that line of sight app link that I posted contradicts that it's solely a radio problem.  I do appreciate the feedback, and I will get better radios at some point.

 

He brings up a good point.  The Gen 1 MXT400's were problematic.  My Gen 1 broke the first day I had it.  It was deaf and power was weak.  It dropped off 100% after a few minutes of use.  most people reported all kinds of issues with the gen 1's drifting and not being able to get proper audio into repeaters.

 

I had three Gen 2 MXT400's.  All of them worked great.  I get 5+ miles mobile to mobile (depending on terrain), I am full quiet into a repeater that is 22 miles from my house.

 

Do your mics have loops for hanging or button style to go on a 2 prong hook?



#29 scottmckinney67

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Posted 30 January 2020 - 10:07 AM

Just spoke to a guy that I really respect and know is knowledgeable on the subject.  Here's our game plan:

1. Ditch midlands on both sides.

2. Use my diamond dual band mobile whip in my attic.  It has a better base with better cable than the midland base and I can tune it slightly for better results.

3. Buy my son an omni dual band that can be tuned, tune it,  and get it above his roof line.  I'll use 25 feet of RG8U or LMR400, ground antenna, and lightning arrester.

4. Test and hopefully enjoy good results :)

 

Wish me luck!



#30 scottmckinney67

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Posted 30 January 2020 - 10:11 AM

He brings up a good point.  The Gen 1 MXT400's were problematic.  My Gen 1 broke the first day I had it.  It was deaf and power was weak.  It dropped off 100% after a few minutes of use.  most people reported all kinds of issues with the gen 1's drifting and not being able to get proper audio into repeaters.

 

I had three Gen 2 MXT400's.  All of them worked great.  I get 5+ miles mobile to mobile (depending on terrain), I am full quiet into a repeater that is 22 miles from my house.

 

Do your mics have loops for hanging or button style to go on a 2 prong hook?

 

I'm only using midland antennas.  I have Retevis RT-99's for the mobile radios.



#31 marcspaz

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Posted 30 January 2020 - 10:15 AM

I'm only using midland antennas.  I have Retevis RT-99's for the mobile radios.

Ah... got you.  I thought you had a Midland radio, for some reason.  I have zero experience with those.  The Midland antennas are not great, unfortunately. 



#32 scottmckinney67

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Posted 04 February 2020 - 08:48 AM

Update: bought a tram 1480 for my son's house.  Going to get that sucker off the ground, probably 16-20 feet.  Using this cable https://www.dxengine...DXE-400MAXDX050 on both our antennas.  I'm mounting my midland whip on a ground plane kit in the attic.  I hope the Tram does the job.  We shall see  :)



#33 marcspaz

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Posted 04 February 2020 - 01:42 PM

That Tram is a monster antenna.  That should do the trick.  The ground plane kit is going to be a huge improvement on your side too.

 

Good luck.  Looking forward to hearing back with the results.


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#34 gman1971

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Posted 04 February 2020 - 01:50 PM

Nah, the Diamond X500N would've been an even bigger monster antenna... :D

 

G.


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#35 scottmckinney67

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Posted 04 February 2020 - 01:51 PM

That Tram is a monster antenna.  That should do the trick.  The ground plane kit is going to be a huge improvement on your side too.

 

Good luck.  Looking forward to hearing back with the results.

 

Thanks.  Hopefully the SWR is low enough to not make our Chinese radio go kaboom haha.


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#36 scottmckinney67

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Posted 05 February 2020 - 05:51 PM

Update: just tested SWR of the tram 1480 on my little nanovna contraption from 460-470 MHz, highest SWR was around 1.7 at the top, got as low as 1.3 towards the bottom.  So no radio kablooey :)  We'll get her sealed up, mounted and grounded soon at my son's house and see what we've got.


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#37 scottmckinney67

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Posted 08 February 2020 - 07:11 PM

Ok.  I installed a nagoya ground plane kit on my midland mobile 6db whip in the attic and ran 50 feet of LMR400.  Installed a tram 1480 base antenna at my son's.  It's approximately 22 feet off the ground, above his roof line, 50 feet LMR400.  We can talk clearly on 3 GMRS channels. The others are very noisy.  There is a noise floor on those three, but the voices are clear and legible.  I was concerned about the Tram not being tuned for GMRS, but the SWR was low according to my cheap analyzer so I went for it.  I'm glad I did, because this gets us talking and has him ready for amateur bands when we get our tech licenses.  When we do, I'll swap the attic midland for a dual amateur band nmo mobile and we're all set.  Also, I am able to hit some vhf and uhf repeaters in my area (within 10-15 miles) with my midland  antenna on low power.  I didn't try at his mom's but I suspect his set up will be much better as he's closer to downtown Columbus and his antenna has more gain.

 

I'm liking these Retevis mobile radios.  They're very easy to program with a tablet or phone.  Once you get them programmed, you don't need them.  You can change channel, volume right from the mic and the mic tells you the channel.  The audio sounds fine to me.

 

Thanks for all the help and suggestions! 


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#38 Soladaddy

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Posted 07 April 2020 - 07:22 PM

What model is the radio? I see a 90 and 95 but no 99. I'm late to the game but there are a few dual band antennas for GMRS, but they are paired with MURS because GMRS is a 3 harmonic of MURS. With dual band antenna the focus is on the VHF side and the UHF just resonates so its usually not a good performer. If you focus on 440 ham and gmrs you can find some 1/4 waves that are very broadband a could cover both. I have a Comet mobile CA-2x4SR that is broadband enough to cover 2M, MURS, 440, and GMRS. It has a very flat SWR across all bands and does well on the VHF bands. I need more testing to make a UHF performance claim. Glad you are making it work.



#39 scottmckinney67

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Posted 07 April 2020 - 07:49 PM

I'll leave radio and compliance aside for now :)  I was able to talk with the Tram and the little whip but I've since bought my son a pctel maxrad 5 element yagi that's resonant on gmrs.  I used google maps, switched to satellite view and drew a line on the map between his house and mine.  That was super helpful in getting it aimed.  If someone knows an easier method, let me know.  With that antenna, I was able to talk to my son almost all the way to my house with a baofeng hand held in my truck.  That's more like it :)  I went ahead and ordered another for my house and will aim them at each other and hopefully get good results.  When I get some definitive results, I'll post them up for future reference.  This is the antenna https://www.amazon.c...0?ie=UTF8&psc=1  It seems to be well made, welded elements and I like where the connection is compared to some others.



#40 Soladaddy

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Posted 08 April 2020 - 12:12 PM

I use Googe Earth for bearing, distance and it will give an elevation profile which is great for line of site issues. While I like the jack of all trades antenna concept, your single band yagi will perform much better and its much smaller.  I plan on using a better GMRS only omni antenna at home (currently using a copper j-pole). For radios, looking for a couple mobiles.






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