x91 base and rover

How high will the base be relative to the rover? The higher the further almost always.

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Not to much of an elevation change between base and rover

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So, the distance will depend on the type of radios in use on the receivers. Assuming they are Internal Satel radios, you can go a long ways.

I can make it from the office, way past the airport (9+ miles) but it is line of sight over the top of town.

One thing that will make the distance longer is to use an antenna extension to move the antenna from underneath the receiver to a 15 foot pole, 10' north of the base. Elevation always beats power it seems.

Make sure the sensitivity of the rover is set to high and use a handheld radio to make sure there is no one else on the same frequency.

M

Thank you Mark. I took your advice and put the antenna extender as high in the air as possible. Also we put it at least 10 feet away from the base unit. WE got almost two miles down the river. This is the distance we needed to complete the job

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Exactly. Try to site the UHF antenna to the North of the base. The chance of a satellite being behind the pole and antenna is least to the North.

I was curious, so I just checked using the [ PacCrest Estimator Tool ] and for

1-Watt, 0 cable length, height 5': Ground Range 1.45 Miles
1-Watt, 18' cable length, Height 15': Ground Range 2.45 Miles
20-Watt, 6' cable length, height 5': Ground Range 2.66 Miles

I adjusted the VSWR, antenna gain for real world) Basically, adding a 18' LMR-195 cable (loss) and putting up in the air (gain) is nearly as effective as 20 times more power. (I used 20 watts instead of 35, because 35 is hard to achieve in field.)

But I want to clarify a few things:

This will not work with 1/4 wavelength short antenna. They require a ground plane and the VSWR blows up if you terminate them on the end of a wire at the top of a pole. The longer antenna with the coil at the bottom (they are standard on the receiver you have) are 5/8 wavelength end-fed-dipoles and they don't require a ground plane, so they work just as well on the end of the cable with a plastic block holding them. When the antenna is on the bottom of your receiver, the inside of the receiver is typically painted with conductive paint which forms the ground plane (on a metal bottomed receiver like the R10, the paint is not required.) The larger the ground plane, the better. So on smaller receivers, the ground plane is greatly reduced (r-squared right?). If you are using a 1/4 wavelength antenna, switching to a decent, correctly tuned 5/8 loaded antenna will make a significant difference.

You need to make sure your cables are in good condition. This is the #1 issue that I have seen over the years. If you break the cable, you can't fix it with tape and the tools that you have available in your pickup. I recommend that you use Velcro straps to fix the antenna wire to the pole so that the wire is not whipped around in the wind all day. I personally just replace all my antenna wires every other year, or at least re terminate the end connections. (This is where your ham radio buddy will come in handy because he has a tool box full of tools for stripping and crimping coax, a soldering iron, replacement connectors and heat-shrink.)

If you can put your base on a hill or slight rise, then you may only be limited by the 'Free Space Range' which is over 100 miles for a 1-watt radio with a decent antenna at 1-watt. That is what happens when we setup in the front yard of of the office, I can see nearly to the other side of the Great Salt Lake (>35 miles) and as long as I am the only person on the frequency, there is not much stopping me from receiving corrections anywhere I can see the base in between. And that is pretty much everywhere.