RTK base station Antenna advice needed.

[Shulerfarm]

First post and am a farmer, not a radio guy. Please excuse my ignorance if applicable.
I have set up a base station to send data packets to my tractor to provide RTK correction information from a base GPS receiver to the radio on the tractor. All this is John Deere equipment using 450 to 470 mhz.
Specs on my current base station: radio outputs 1.6 Watts at 464.5 mhz to a 100 watt amplifier specifically built for my frequency and the output pulse created by the radio. (Standard amplifier would not work because the relay inside would click on and off at each pulse and not work). From amplifier to polyphaser surgeprotector directly mounted to ground rod, then LMR400 up a pole to about 45'. Using a cheap Comet CA-712EFC antenna which is a 9 dBi omni direction antenna. I get a weak signal up to about 7 miles. Radio in the tractor gains and losses signal every few seconds. (Works ok because it can go into an RTK extend mode for 5 minutes without autosteer interruption)
In South Carolina we have many patches of pine trees up to 75' tall throughout our area. Not ideal for radios.
Main question is what antenna do I need to upgrade to gain at least 9 miles total and have a more reliable signal. Would a Laird FG4607 be a major improvement or just slight? I have also read that a dipole antenna can be great for transmitting through foliage but they can get pricey.
Please provide any specific antennas you think may help.
Also do I need to go higher? I can mount on top of a grain elevator at 100', but would rather not. My earlier testing, without an amplifier, I got about the same range at 100' high vs 20' high with the Comet antenna. About 4 miles.
Thanks in advance.

 

[mrsvensven]

Is this one way communication from the base to the tractor, or are you also trying to receive a signal from the tractor to the base?

Do you have a way of monitoring the frequency to check if some other user nearby is also on that same frequency and interfering with you? Typically frequencies require a license to transmit and coordination to avoid interference to or from nearby users. I assume based on your frequency choice that you've skipped licensing and coordination.

9dBi is a decent antenna and (without knowing all the details such as terrain and clutter) I think it's likely that changing antennas won't make mich difference and increasing your antenna height is where you should focus your efforts.

 

[Shulerfarm]

Is this one way communication from the base to the tractor, or are you also trying to receive a signal from the tractor to the base?

Do you have a way of monitoring the frequency to check if some other user nearby is also on that same frequency and interfering with you? Typically frequencies require a license to transmit and coordination to avoid interference to or from nearby users. I assume based on your frequency choice that you've skipped this step.

9dBi is a decent antenna and (without knowing all the details such as terrain and clutter) I think it's likely that changing antennas won't make mich difference and increasing your antenna height is where you should focus your efforts.

One way from base to tractor. The curren John Deere dealer base station that will soon be decommissioned is on 461.5 mhz versus my 464.5 mhz. Are these too close a frequency? This base station is transmitting about 2 miles from mine at 50 Watts and a large antenna on a 130' grain elevator. Reaches about 20 miles.
I went thru a frequency coordinator to get my license. I would assume I didn't get a frequency # close to a neighbor.
Our terrain is generally flat , about 25' rise over 8 miles. Could be 50 acre open field, then 1/2 mile of pine trees to the next field. These patches of pine trees keep adding up the farther you go.

 

[mmckenna]

One way from base to tractor. The curren John Deere dealer base station that will soon be decommissioned is on 461.5 mhz versus my 464.5 mhz. Are these too close a frequency?

No.

This base station is transmitting about 2 miles from mine at 50 Watts and a large antenna on a 130' grain elevator. Reaches about 20 miles.

That's what I'd expect from a setup like that.

I went thru a frequency coordinator to get my license. I would assume I didn't get a frequency # close to a neighbor.

464.500 doesn't require frequency coordination. It's a very common business frequency used for itinerant use, not fixed use.
It may have other users on there. Probably not a good choice for what you are doing, and not something a legit frequency coordinator should have put you on.

Our terrain is generally flat , about 25' rise over 8 miles. Could be 50 acre open field, then 1/2 mile of pine trees to the next field. These patches of pine trees keep adding up the farther you go.

There's no reason why you should need a 100 watt amplifier to get several miles of coverage. 5-10 watts and a good antenna should work just fine.

If this set up never worked right, I'd suspect one or more of the following:
There's an issue with the coax, connector, amplifier or radio at the base station.
There's an issue with the receiver, coax, power, connector, antenna mount, or antenna on the tractor.
A good radio tech could save you a lot of time, headaches, and spending money on test equipment you'll only use once. It might be worth calling a local radio shop (NOT John Deere) and pay for a tech to come out and look at your system.

If the setup worked fine, then failed, then you may have water in your coaxial cable.

If you are in the USA, the FCC rules would suggest that your frequency coordinator took advantage of you:

10)This frequency will be assigned only to stations used in itinerant operations, except within 56 km (35 miles) of Detroit, Mich., where it may be assigned for either itinerant or permanent area operations (i.e., general use).​

And there's no reason he should have told you 100 watts was OK. That's overkill, and not covered by the FCC license:

34) Operation on this frequency is limited to a maximum output power of 35 watts.​

Throwing 100 watts at the issue isn't going to help.
Also, be wary of John Deere, they're pretty well known in the two way radio industry to tossing these RTK systems on any frequency they feel like. We've had issues with them causing interference locally. I believe the FCC finally busted them for what they were doing out here.

 

[clbsquared]

I run an RTK system with a Henry 50 watt amplifier, on a 120’ tower with a generic omnidirectional antenna. Our terrain is much the same as yours. Open fields separated by heavy pine forests. The only issue I have is on the headlands that are against the woods. There’s not much you can do about that. The tall trees block the signal regardless of wattage or antenna height. My suggestion would be for you to at the very least DOUBLE the hight of your existing antenna and possibly reduce the amplifier to 50 watts. The 100 watt may be throwing it out too far making it difficult for the receiver on the tractor to pick up. Also, what antennas are you using on your tractor receivers? I’ve found that the standard rubber antenna that comes with it is horrible. I’ve switched all of my antennas to a Laird Phantom antenna on a magnetic base and have them mounted on the top of the cab at the back. Don’t let your John Deere rep talk you into using their “hi gain” antenna. It’s nothing more than a dual band scanner antenna.

 

[prcguy]

464.500 is also a repeater output frequency, are there other users that could be interfering? Can you monitor the frequency with a receiver to see if other users or a repeater is causing problems when your equipment transmits?

 

[Shulerfarm]

No.



That's what I'd expect from a setup like that.



464.500 doesn't require frequency coordination. It's a very common business frequency used for itinerant use, not fixed use.
It may have other users on there. Probably not a good choice for what you are doing, and not something a legit frequency coordinator should have put you on.



There's no reason why you should need a 100 watt amplifier to get several miles of coverage. 5-10 watts and a good antenna should work just fine.

If this set up never worked right, I'd suspect one or more of the following:
There's an issue with the coax, connector, amplifier or radio at the base station.
There's an issue with the receiver, coax, power, connector, antenna mount, or antenna on the tractor.
A good radio tech could save you a lot of time, headaches, and spending money on test equipment you'll only use once. It might be worth calling a local radio shop (NOT John Deere) and pay for a tech to come out and look at your system.

If the setup worked fine, then failed, then you may have water in your coaxial cable.

If you are in the USA, the FCC rules would suggest that your frequency coordinator took advantage of you:

10)This frequency will be assigned only to stations used in itinerant operations, except within 56 km (35 miles) of Detroit, Mich., where it may be assigned for either itinerant or permanent area operations (i.e., general use).​

And there's no reason he should have told you 100 watts was OK. That's overkill, and not covered by the FCC license:

34) Operation on this frequency is limited to a maximum output power of 35 watts.​

Throwing 100 watts at the issue isn't going to help.
Also, be wary of John Deere, they're pretty well known in the two way radio industry to tossing these RTK systems on any frequency they feel like. We've had issues with them causing interference locally. I believe the FCC finally busted them for what they were doing out here.

I went thru my local radio dealer to obtain license. I asked for a frequency in the 450 to 470 mhz range and wanted the option of a mobile base. If I want to install drain tile using my RTK gps receiver, a close base gives better vertical accuracy on elevation. I wanted a fixed base station but be able to grab the receiver/radio and create a base station at the field using a battery and small antenna. "No problem" we will make it an itinerant use frequency. (No idea that I am using a general use frequency) There are 3 others on my list. Was told the last two are general use for receiving only. I don't know. The company who built my amp wouldn't build it under 100 watts. With my foliage or tree situation I needed all the power I could get.
My frequencies listed on my license: 464.5000, 464.5500, 469.5000, and 469.5500. Thanks for any advice on what my next set should be.

 

[Shulerfarm]

I run an RTK system with a Henry 50 watt amplifier, on a 120’ tower with a generic omnidirectional antenna. Our terrain is much the same as yours. Open fields separated by heavy pine forests. The only issue I have is on the headlands that are against the woods. There’s not much you can do about that. The tall trees block the signal regardless of wattage or antenna height. My suggestion would be for you to at the very least DOUBLE the hight of your existing antenna and possibly reduce the amplifier to 50 watts. The 100 watt may be throwing it out too far making it difficult for the receiver on the tractor to pick up. Also, what antennas are you using on your tractor receivers? I’ve found that the standard rubber antenna that comes with it is horrible. I’ve switched all of my antennas to a Laird Phantom antenna on a magnetic base and have them mounted on the top of the cab at the back. Don’t let your John Deere rep talk you into using their “hi gain” antenna. It’s nothing more than a dual band scanner antenna.

On the tractor I have tried the standard 12" JD antenna and a Laird B4505CS 5 dB half wave antenna. Same results. My amplifier was built by Henry Radio Amplifiers specific to my frequency with radio set to 1.6 watts output. I could lower the radio watts and this should lower the output out of the amplifier. Lately when planting near my base, I removed the amplifier and just run on the 1.6 watts. I get about 3 miles, maybe 4. I was hoping the amplifier would easily get me 9 miles without having to mount the antenna at 120'.

 

[clbsquared]

W

On the tractor I have tried the standard 12" JD antenna and a Laird B4505CS 5 dB half wave antenna. Same results. My amplifier was built by Henry Radio Amplifiers specific to my frequency with radio set to 1.6 watts output. I could lower the radio watts and this should lower the output out of the amplifier. Lately when planting near my base, I removed the amplifier and just run on the 1.6 watts. I get about 3 miles, maybe 4. I was hoping the amplifier would easily get me 9 miles without having to mount the antenna at 120'.

When planting close to your base antenna, you’re better off disconnecting the antenna from the receiver radio instead of lowering the wattage on your amplifier. I’m not sure why they would only allow you to buy a 100 watt amp. That sounds a little suspect to me. Because Henry built my amp to my specifications. And they had no issue with building one at 50 watts for my application.

 

[sonm10]

I disagree with @mmckenna
John Deere is the best resource for this issue. The dealership should have people knowledgeable enough to help with your situation. Receiving data packets should not take much. I suspect an issue with the receiver.

 

[clbsquared]

I disagree with @mmckenna
John Deere is the best resource for this issue. The dealership should have people knowledgeable enough to help with your situation. Receiving data packets should not take much. I suspect an issue with the receiver.

Respectfully, I’ve dealt with these RTK systems enough to know that John Deere is NOT the best resource for this issue.

 

[Shulerfarm]

I disagree with @mmckenna
John Deere is the best resource for this issue. The dealership should have people knowledgeable enough to help with your situation. Receiving data packets should not take much. I suspect an issue with the receiver.

First post and am a farmer, not a radio guy. Please excuse my ignorance if applicable.
I have set up a base station to send data packets to my tractor to provide RTK correction information from a base GPS receiver to the radio on the tractor. All this is John Deere equipment using 450 to 470 mhz.
Specs on my current base station: radio outputs 1.6 Watts at 464.5 mhz to a 100 watt amplifier specifically built for my frequency and the output pulse created by the radio. (Standard amplifier would not work because the relay inside would click on and off at each pulse and not work). From amplifier to polyphaser surgeprotector directly mounted to ground rod, then LMR400 up a pole to about 45'. Using a cheap Comet CA-712EFC antenna which is a 9 dBi omni direction antenna. I get a weak signal up to about 7 miles. Radio in the tractor gains and losses signal every few seconds. (Works ok because it can go into an RTK extend mode for 5 minutes without autosteer interruption)
In South Carolina we have many patches of pine trees up to 75' tall throughout our area. Not ideal for radios.
Main question is what antenna do I need to upgrade to gain at least 9 miles total and have a more reliable signal. Would a Laird FG4607 be a major improvement or just slight? I have also read that a dipole antenna can be great for transmitting through foliage but they can get pricey.
Please provide any specific antennas you think may help.
Also do I need to go higher? I can mount on top of a grain elevator at 100', but would rather not. My earlier testing, without an amplifier, I got about the same range at 100' high vs 20' high with the Comet antenna. About 4 miles.
Thanks in advance.

Can someone please tell me which of these frequencies I should be using. I was told I was going to get two frequencies. one for base and one for a repeater if necessary. I had no idea that some of these may be shared with others in my area. A screenshot of my license info is above in earlier post. My frequencies listed on my license: 464.5000, 464.5500, 469.5000, and 469.5500.

 

[clbsquared]

Can someone please tell me which of these frequencies I should be using. I was told I was going to get two frequencies. one for base and one for a repeater if necessary. I had no idea that some of these may be shared with others in my area. A screenshot of my license info is above in earlier post. My frequencies listed on my license: 464.5000, 464.5500, 469.5000, and 469.5500.

Use the one marked FBI.
I’m still wondering why they issued you that many frequencies when you only needed one. Someone must not have understood what you needed. Your station class should be FB6 and your emission designator should be 11K2F1D. The radio service should be IG Industrial/Business Pool

 

[WB5UOM]

Not FB6 just FB ...pretty sure his fixed location isnt moving around so FBI is not right either

 

[clbsquared]

Not FB6 just FB ...pretty sure his fixed location isnt moving around so FBI is not right either

His FB is on low band VHF. That won’t work for RTK. His only option right now is the FBI which is UHF.

 

[mmckenna]

Can someone please tell me which of these frequencies I should be using. I was told I was going to get two frequencies. one for base and one for a repeater if necessary. I had no idea that some of these may be shared with others in my area. A screenshot of my license info is above in earlier post. My frequencies listed on my license: 464.5000, 464.5500, 469.5000, and 469.5500.

It would help to see the entire license.

The 464.500 is showing FBI, which is for a fixed base/itinerant.
The other 3 are showing MOI, which is for mobile/itinerant.

Sounds like the guy doing the licensing did not quite comprehend what was going on. If you had a base at a fixed location, that isn't an itinerant, and shouldn't have been licensed as such.

Since you have access to these 3 other frequencies, you might want to try some of the others to rule out co-channel interference.

But I still think you have some fundamental issue with your setup. There's zero reason why you should need 100 watts to get this to work right given your topology. I've covered areas much bigger than this with 10 watts. You can spend a lot of money on buying new parts, but it's going to get expensive. A good radio tech with the right tools can probably find the issue in an hour. It would be money better spent.

And while some John Deere dealers might be better than others, locally, they did some stupid stuff with their RTK systems. I don't know how well those guys are trained on actual two way radio systems, or if they are just trained on the basics and how to sell more John Deere equipment. On the other hand, an experience radio tech can find the actual issue quickly.

If I was local (I'm not) I'd offer to come out and help troubleshoot the issue for free. These systems are not that complex from an RF standpoint.

 

[clbsquared]

It would help to see the entire license.

The 464.500 is showing FBI, which is for a fixed base/itinerant.
The other 3 are showing MOI, which is for mobile/itinerant.

Sounds like the guy doing the licensing did not quite comprehend what was going on. If you had a base at a fixed location, that isn't an itinerant, and shouldn't have been licensed as such.

Since you have access to these 3 other frequencies, you might want to try some of the others to rule out co-channel interference.

But I still think you have some fundamental issue with your setup. There's zero reason why you should need 100 watts to get this to work right given your topology. I've covered areas much bigger than this with 10 watts. You can spend a lot of money on buying new parts, but it's going to get expensive. A good radio tech with the right tools can probably find the issue in an hour. It would be money better spent.

And while some John Deere dealers might be better than others, locally, they did some stupid stuff with their RTK systems. I don't know how well those guys are trained on actual two way radio systems, or if they are just trained on the basics and how to sell more John Deere equipment. On the other hand, an experience radio tech can find the actual issue quickly.

If I was local (I'm not) I'd offer to come out and help troubleshoot the issue for free. These systems are not that complex from an RF standpoint.

Against my better judgement, I allowed our local Deere dealer to install ours. I was reluctant but allowed them to do it because I was out of time. And I needed the sub 1/2” accuracy of RTK as opposed to the 1’-3’ accuracy of FS2. A few months later all the problems started showing up. The power supplies burnt up because they were too small. The amplifier burnt up because it was placed on its edge in a corner and had no air flow. The loss on the coax was insane. They had 50+ feet of coax coiled up and taped to the antenna base because they didn’t know how to cut to length and terminate it with a new end. The low voltage wire from the 12 volt power supply to the receiver should have been only 12’ long. They used an entire 500’ box of wire and just pulled the two ends out and left the rest at the base of the tower. The polyphaser wasn’t grounded. It was taped to the tower with duct tape. The list goes on and on. When I finally had the time, I fixed everything. It’s been running flawlessly for the last 5 years without so much as a hiccup.

 

[mmckenna]

When I finally had the time, I fixed everything. It’s been running flawlessly for the last 5 years without so much as a hiccup.

Yikes. I've seen some crappy installs in my day, but never anything quite that bad.

Might have to add this to my list of possible retirement side-hustles.

 

[AM909]

My guess: nowhere near 100 watts is getting to the antenna.

Who installed the antenna and put the connectors on the LMR400 cable and were they all new at the time? Got pics?

Which amplifier model, exactly? 1.6 / 100 seems like a lot of gain. [I wander off and find the Henry specs] Yes, 5 in / 100 out is the lowest output spec for continuous/base and should be plenty for this application as long as much of it is actually getting to a working antenna. A tech with a wattmeter would first check forward and reflected power at the amp output and then (if necessary) at the antenna.

Got a pic of the mobile install? It may not be needed, but a real antenna on top of the cab for the mobile makes sense if it can be done in a way that's durable. Just a cheap Laird or PCTEL 1/4-wave spike.

Others have covered how crazy it was to put you on 464.500 and 464.550, freqs that have been commonly put in radios by default and used without proper licensing for decades. There's mostly no such thing as unshared channels for your application, but depending on how far out in the country you are, a proper licensing guy should be able to find and co-ordinate something that's not in use anywhere nearby.

[Re-reading the thread for more detail, I see:]

Lately when planting near my base, I removed the amplifier and just run on the 1.6 watts. I get about 3 miles, maybe 4.

Well, that sounds about right. Maybe there isn't a problem with the feed/antenna. I'm not familiar with their amps any more, but if it's +13 dB gain at 5W in (=100W out) and the input is turned down to 1.6W and the gain is the same there, output would be 32W, which might yield exactly the coverage you're seeing (and, coincidentally, be below the earlier-quoted 35W legal limit). Hmmm.

[and in the Henry specs:]

On amps listed as 5 watts input, specify your drive power of 1, 2, 3, 4 or 5 watts to get rated power output

 

[Shulerfarm]

Did some research and find all four of my frequencies are listed as typical itinerate use frequencies. I may be getting interference from others nearby. I expected a frequency specifically coordinated for me in my area. No other users of this frequency in 30 mile radius. Three times my monitor has thrown a code stating some form of interference. My original thought was pay for a frequency that I can use as a base or itinerate (local, maybe 15 mile radius). I didn't know where to install my base without some testing first. Needed a frequency to use first (I did not want to step on anyone's toes) I have three locations picked : 1. At irrigation well, high voltage would need to be stepped down but is centrally located, next to road and suseptible to theft; 2. at shop above a small well, has power and no theft, 45' high; 3. At grain facility 100' high, more coax, shading issues for gps, also edge of farm needs to reach 9 miles.
I am going to talk to the radio dealer who setup the license. Also looking at improving antenna and maybe gain some height.