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Unbelievable RC

So you're an RC hobbyist in need of a tool for measuring temperatures. Perhaps you've just gotten into nitro, or you've just gotten more serious about on-road racing. Pro Exotics is a reptile breeder & seller that spun off a brand called TempGun.com to sell -- you guessed it -- temp guns to enthusiasts from many hobbies, including yours & mine. I've put two of their models to the test to see how well these very affordable tools could meet one RCer's needs.

Initial Impressions

All you need to do to get either probe into action is open the package -- the battery comes pre-installed in each. The PE-1 includes an optional wrist strap, and given the small size of the probe, I highly recommend using this. Appearances aside, the size difference between the two models was very noticeable by the feel in my hands. The PE-1 felt like a small probe, while the PE-2 held more like a cel phone or handheld GPS. The smaller model has a smaller display, but both are plenty large for readability, and the digits are very clear. Button positions are very different, but both feel easy and natural to find with my thumb without having to look.


Here are the advertised specifications from TempGun.com's web site:


I spent two weeks using the two probes in various applications, not the least of which being with the RCs. I used them to keep track of temperatures of charging and discharging batteries, tested ground and tire surface temperatures, and took countless engine temperature readings while running and tuning an 1/8th scale buggy. I also did some controlled environment tests indoors to examine repeatability and compare the results from the two probes, and to look for undesirable factors that could throw off the readings. I also used them extensively with an aquarium during a spell of wildly fluctuating weather, and helped diagnose some nagging climate control issues at work. Keeping in mind the stated accuracy ranges above, let's have a look at how it all panned out.

(Note that all temperatures cited below are in Fahrenheit {F}.)

Indoor Bench Tests

The first thing I wanted to see was how close the measurements of the two probes would be to each other. Because of the different D:S ratios (distance to spot -- distance from target vs. diameter of area measured, bigger being better), I tested the PE-1 at 1" from the measured surface and the PE-2 at 8". Measuring surfaces in the 70-80 deg. range, I never saw a difference of more than 0.2 deg. between the two probes, and at that level of precision, it's extremely likely that the measured surfaces were changing that much between readings or that I simply wasn't lining up the probes at the exact same angles.

Next up, I wanted to see if the probes were affected by visible light -- they're certainly not supposed to be, but poor-quality sensors might not pass the test. I printed two large gradients on a sheet of heavy white paper, one white to black, and one across a color spectrum. After the test sheets dried and sat in a closed room for awhile, I ran each probe down the length of each gradient, just far enough away to avoid any shadows. I saw fluctuations of up to 0.2 deg. in either direction, with no discernable trends. I repeated the same test with plain white paper and saw the same level of fluctuation. While I was at it, I also looked at readings of a single area from different angles, and didn't see any change to worry about from straight up & down to 45 deg. inclined.

I compared the TempGun.com probes' readings to those of two analog (alcohol) thermometers and a Venom Racing onboard temperature monitor and at room temperature, they were all within 1 deg. of one another.

Outdoor Tests

I re-tuned and ran my Ofna Ravager (c-hub 9.5 with a Force .28 engine) on a sunny day with ambient temperatures in the 79 deg. range. The temp guns were used to get readings from the driving surface (asphalt), tires (slicks), and of course, the engine. In real world use, the differences of physical design between the PE-1 and PE-2 really separated the two. The PE-2, with its laser pointer and narrow beam, was very convenient for picking up surface temperatures at various points around a makeshift course by just standing back and pointing. For everything else, though, I found the PE-1 to be more convenient. The size didn't matter all so much, but the wrist strap did. More importantly, though, it was much easier to get the PE-1 lined up with the target due to the rounded shape of the sensor end which shows you where it's centered. For tires, I could just place it directly against the rubber and hit the button and always know that I was giving the sensor a full eyeful of what I wanted it to read. For engine temps, it practically lined itself up in the center of the head thanks to the round shape, and only a little wiggling around with the scan button depressed would give me the peak reading I wanted. Using "MAX" mode made this easier still.

With the PE-2, I had trouble estimating where I was pointing. This may seem ironic, given the PE-2's built in laser, but that pointer is not at all accurate at close range due to its 1/2"+ offset from the sensor lens. To its credit, it did give more precise readings of my engine than its smaller sibling. The narrower field of its sensor lets it really focus on just the glow plug and base of the head, and the result was a consistently higher reading versus the PE-1. The problem was getting the magical high reading, itself. For purposes of this review, I found myself kneeling down and leaning the car away from me on two wheels so that I could see the engine from the side. Then I'd roughly position the probe and tilt it away from me so that I could see the sensor lens opening and try to get in and line it up with the center of the engine head, watching the temperature fluctuate on normal mode. The lack of any printed or molded indication of the sensor opening on the PE-2 makes this process a pain.

My biggest grief with the PE-2, though, starts just a hair after 199.9 degrees. You see, the hundreds place on the display is only wide enough to draw a "1." When you go to 200, the tens place becomes the new hundreds place, the ones place becomes the new tens place, and the tenths place becomes the ones place. If that has you confused, just look at the PE-2 picture below -- it's reading 205 deg. F, not 20.5 deg. F. How awkward is that? I don't mind losing the extra precision, but the small 3rd digit is something I just couldn't get used to.


(No, I wasn't taking readings with the probes angled like that -- I angled them to get good lighting for the photos.)


Monitoring batteries on the charger or discharger was the same experience with either of the two probes. Getting away from the RCs, the PE-1's wide D:S was actually helpful in aquarium use for averaging out minute water surface differences, but the PE-2's laser was a big hit with the fish -- I've never seen them so excited! The PE-2 was most convenient for measuring temperatures of walls, ducts, and full-scale car engine components.

In Summary

Both the PE-1 and PE-2 give good readings that are well within their advertised accuracy ranges, and each works well for its design. The more different things I used them for, though, the more clear the trend became -- for small things up close, the PE-1 was more convenient, whereas anytime a distance was involved, the PE-2 was the clear winner. Given that most of the temperature-sensitive things we do in the RC world are looked at up close, I can't justify the extra cost and size of the PE-2. It can give more precise readings as was the case with the nitro engine, but the regular hassle of hunting around for its sweet spot leaves the cons outweighing the pros for me. In normal use in, for instance, a race, be it the end of a warm-up period or the middle of an enduro, I want to have the probe set to MAX mode, lean down towards the car with probe-in-outstretched hand, and hold the button for at most a second or two while I wiggle it very slightly to get the highest reading before sending the vehicle on its merry way.

So, PE-1 it is, for me at least. But what about the competition? I've used the budget Raytek models in the past, which they now offer in their MiniTemp line. I like the gun-like form factor of the Rayteks, and at a street price of around $45 for the entry-level model with a laser pointer, the price is right there with the TempGun.com PE-2. However, the cheapest RayTek that has a max. temp display is the MT6, which will set you back at least $70. Believe me, after using the Pro Exotics probes, I never want to use a gun with no "max" mode again. Now, the design of the Raytek MT6 makes it easier to use than the PE-2, but I'd take the PE-1 for $25; add TempGun.com's optional metal case with extra battery, and it's still 1/2 the price of the Raytek. Plus, the PE-1 and PE-2 have 5 times the display resolution of the Rayteks below 200 deg. F (0.1 deg. F vs. 0.5).

I have also used the Venom Racing onboard micro temperature monitor. This one is a steal at $18 and keeps track of minimum and maximum temps, but unless you're really clever with your mounting and/or body painting (leaving a clear window to view the temp reading), it's not going to take the place of a handheld temp gun.

For RC'ers, the PE-2 isn't the best choice, but the PE-1 is a very good value. I only wish the PE-1 either had a better D:S ratio or a long, narrow end that could reach down closer to a the base of nitro engine's head. For $25, though, I can't really complain!



(Ratings based on RC hobby use.)