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JetBeam Jet-u


 Budda    03 Apr 2017 : 17:02

JetBeam Specs: LED: CREE XP-G2 LED Power Source: 1 x AAA Battery (Alkaline or NiMH) IPX Rating: IPX-8 (Waterproof and submersible up to 2 meters) Impact Resistance: 1 meter Brightness Outputs: High – 135 Lumens – 48 Min. Medium – 25 Lumens – 4 Hours 18 Min. Low – 1.5 Lumens – 35 Hours Peak Beam Distance: 46 meters Peak Beam Intensity: 518 cd Dimensions: Length – 2.77” (70.4 mm) Head Diameter – 0.56” (14.2 mm) Body Diameter – 0.58” (14.8 mm) Weight: 0.47 oz. (excluding battery) (13.2 g)

They Jet-u came in a plastic box, that can be opened without cutting any plastic.


The dark spot on the box of the Jet-u is an autograph left by one of the couriers (was present also on the shipping envelope) with a cigarette.
Inside each box you will find: the light with the clip installed, spare o-rings, lanyard, instructions and warranty card.

The anodization is on the grey side of the spectra.

Thrunite TiS, UltraTac K18, JetBeam Jet-u, AAA battery

Overall the sizes are comparable: the Jet-u is 70 mm long and 15 mm wide and weights 13,6 grams.

Rather smooth body, with a wide portion of knurling on the head.

Physical polarity inversion protection at the head, so no flat top cells.

No tripod screw at the tailcap, while the major sister Jet-I MK has it. There are holes for lanyards and splitrings.

Also, on the Jet-I MK there is a reflector, while on the Jet-u there is a TIR lens.

I managed to unscrew the pill from the light. The plastic beige thing above the pill is the optic’s casing. Modding this light is very easy.

UI

Fully twist the head to turn it on, untwist to turn it off.
Quickly untwist and twist again for changing the level (in high, mid, low, high, mid, low loop).
The light has memory mode. There are no strobe/flashing modes.

Runtime and output
Runtime and output testing have been done using Tronic EnergyEco 950mAh AAA nimh battery.
I expect the Jet-u to have better performance with Eneloop or Eneloop PRO batteries.
JetBeam doesn’t speak about 10440 compatibility, so I have not tested the Jet-u with li-ion batteries.

Sampling rate is every 6” for the high mode, and every 90” for mid mode.


The regulation is good: at high mode I got 56 minutes of constant output (there is no practical difference between 109 and 103 lumens) before the light quickly dims, ad mid mode 390 minutes.

Beamshot at 0.5 meters from the wall
A small disclaimer: after I had took apart the Jet-u and left the pieces on my desk when I touched by mistake the edge of the plastic TIR optic with the soldering iron, thus causing a small portion to melt in in one point. It is visible on the spill and a bit on the hotspot.

Jet-u with other AAA lights with reflector and around same output. The Jet-u has wider spot and spill.



I compared the Jet-u and the Quantum because they have a tir optic and roughly the same output.
The spot of the Jet-u and the quantum is the same to my eye, while the spill of the Jet-u is wider.


I don’t know why the camera shows the beam a bit on the green side when underesposed. On all my CW lights with optic, the beam is barely warmer than a CW.

My thoughts:
The Jet-u is the smaller and slightly cheaper version of the bigger Jet-I MK from JetBeam: design, general construction (there are differences in the head internal construction), anodization and UI are almost the same. The main difference, apart from the different battery, is the TIR optic of the Jet-u. The Jet-u is a small and well built light.
The Optic gives a beam better suited for closes distance, with bigger spot and spill, but less throw.
The 3 output are well spaced, max output is in line with other AAA lights, while low mode is on the low side (some people actually prefer a lower low mode).
Generally AAA lights are good EDC/keychain lights, and I think it would be a great for a gift: it is easy to use, small and works with commonly available batteries.

Thanks to AntoLed for the camera and the luxmeter.
Thanks for reading.