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Grid Square DM31

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Potential VHF rover sites in AZ's grid DM31. Be careful.
DM31 dimensions are 117.9 by 69.2 miles.
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Tillotson Trailhead, DM31ox38

Latitude, Longitude
31.992890, -112.805990
Map Location Near city of Lukeville, Pima County, AZ, Altitude 1800
Map See Google map, Bing map, Mapquest, OpenStreetMap, Beam heading

Last update: 2020-01-10
Comments by: Larry, Petr WO7R, AG6EE

Tillotson Trailhead 1 Tillotson Trailhead 2

This is the Tillotson Peak Wayside parking area along AZ state Hwy-85, N Ajo Sonoita Hwy, in the Organ Pipe Cactus Wilderness area. It's one-half mile south of the DM31-DM32 grid line.

Larry WO7R related his understanding of the DM31 situation: It's very easy to access, and as long as you operate with "wilderness rules" in mind, you should not expect trouble with the rangers.

  • Must use battery power, not generators. This is key.
  • Must use sandbags or weights to anchor guy lines.
  • It helps to patrol the area to reduce litter/clutter. This is not strictly needful but it really helps get rangers on your side.
  • The area is pretty quiet. We had a couple hikers come by and park. They left to go hiking. We bothered noone and noone bothered us.
  • The rangers do not want or allow us to park in places like the campground or the visitor center parking lot. The rule is, we can operate as long as we don't bother others. At those locations (visitor center, campground), they deem that we do.
  • The campground has some generators-allowed hours, but not terribly useful to us anyway. Generators are allowed nowhere else in the park (wilderness rules). Trailheads generally look good. Petr AG6EE has identified other spots, but to me, the Tillotson site looks best, hands down.
  • A photo above is one I took as I left the park, so it shows the turnout/wayside from the northbound lane. One would normally approach from the southbound lane.
  • You should be prepared to go further into the park, at the Visitor Center, to pay fees, but if you set up here early, you generally don't even have to pay your fees for the day until later. A "senior pass" can be helpful.
  • Petr AG6EE identified several other potential spots in the park, but none are as straightforward as this one. Basically, any trail head parking lot would do, but many are nestled too close to the local mountains. This one has clear sight lines. Will it be more crowded when the park is usier? No way to know, but it's doubtful. Get there early, set up, and you're fine. It even has RV-sized parking spaces if you need them.
  • The Tillotson site is also 100 per cent paved roads, including the site itself. Any rover vehicle whatever will get there. You don't need a Jeep or 4WD or anything special. That's not necessarily true of other potential sites.
  • Personally, if I (Larry WO7R) returned with a friend who has the gear, this is the one and only place to try.
  • Outside the park, there is a potential site or two near the confluence of DM31-31 and DM41-41. Those are on tribal land and you might be able to operate on the should of a tribal road somewhere. How acceptable this is, I don't know.
  • Based on Petr's experience, 500 watts of battery power is ample and a maximum level he only needs some of the time. He had one battery at 48v for the amplifier and the other battery was 12v for the rig. Based on my operating at home from DM32 (with a 70-foot tower) then 250 watts will work the entire continental US. A push-up mast at 30 feet is probably good for similar coverage to what I get at home, because Petr did not need full 500-watt power very often for MSK144.

John NA6L and Petr AG6EE examined the merits of many DM31 operating locations:

  • The Tillotson Trailhead Lot was the only one we were sure would work because we've operated from there before.
  • It is super easy to access and has a great horizon in most directions.
  • It is safe and secure being next to the main road.
  • Summer temperaturs can reach 120F.
  • In the summer they've seen people sitting under their RV awnings in the parking lot while their engine/generator was running.
  • There are so few people there in the warmer months that rangers might not even care about some running machinery for their "a/c".
  • Even if you just cooled your vehicle down and charged your batteries every hour for 20 minutes there is a good chance you could get away with it.
  • You might also be able to operate from the campground with no issues.
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