Surefire kx4

vicv

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Hey everyone. I was looking for an ma-02 and I found a somewhat local dealer that has one of these heads, new, for $15usd. I figure for that price, why not. I'm more of an incan guy, but I believe this is a replacement head for a 6p type light and it has the led driver built in, so heat sinking should be good. Worth picking up? I'll probably pop it on a solar force l2p if I get it
 

vicv

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Ok so this thing looks pretty good. Lighter than I expected. I think it does work, as it flashed quickly when screwing it in one time. But there's definitely a connection problem somewhere with my solarforce host. Every other drop in I've ever used has worked in it. But this kx4 head isn't working. I wonder if the negative spring isn't wide or long enough. I don't know the difference between sure fire and solar force hosts
 

michaex

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@vicv I'd try it without a tailcap first, using a multimeter. If that doesn't work, try it without the body altogether. And slowly narrow down :)
 

vicv

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Ya I bypassed the light with wire and an 18650. It appears to be the negative spring. I assume surefires have a tighter inside barrel than the solaforce. I stretched out the negative spring width wise, and it works. Pretty flawlessly actually. With 2 cr123s that were spent in my aviator. Same brightness as fresh ones from what I can tell. 18650 still a bit too short, needs a small button magnet. Won't be using like this, just to test. Very dim anyway. What's weird is that solarforace has worked with all surefire incans, lumens factory incans, a solarforce and a vinh made led drop in, one I made. A solarforce k3. But for some reason this kx4 is just a tad too narrow. Hopefully this gives me reliable connection
 

vicv

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So I'm not exactly going to review this. I mean it came out around 2010 and things have moved on a bit…..but it's ok. Very floody for my tastes. It's a much shallower reflector than any other p60 type drop in I've seen. Combined with a pretty large die, it's very floody. My convoy s2+ with an sst-20 in a smooth reflector has a much tighter hotspot, and that's a small reflector tube light. But that emitter is a lot smaller. It's hard to tell how many lumens it's scattering around everywhere, but 120-150 would be a fairly accurate guess. I've read some reviews, and apparently it was a pretty good thrower? I was into incans still then, so wasn't up on the leds at this time, so maybe it was a thrower for early leds. I'd say the beam profile is pretty close to a malkoff m61 from 8 or so years ago with the small reflector he uses.
Overall not a bad light engine, especially as it's nib from over a decade ago. I will see how it performs outside after it gets dark. Regardless, it'll be a good way to get more juice out of those cells from my aviator once the regulation kicks out. Along with my trusty stream light 1L-1AA. The stream light also throws a tighter beam
 

vicv

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Ok so it's not too bad. It makes everything look like Fuji 400 film but that's just cool leds I imagine. This thing is so floody it's kinda funny. Normally I like a beam from A2 to m3 type of beam. If I'm pointing my light at 12 o'clock, I expect to illuminate 11 and 1 as well if looking at around 50-60'. But intense at the center. This thing lights up 10-2 about evenly, and 9-3 as well. There doesn't seem to be a hotspot.
Were these a particularly, cheap part originally? As I understand it, this was an upgrade head for the 6/9 p(and others like it) and factory head on the g2L. Is it supposed to feel kinda…..cheap. This head doesn't have that substantial/solid feel as something like an a2 or an m3.
 

haveyouseenthelight

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Thanks for reminding me about the kx4, I bought one of these back when they were new to upgrade my 6p original. I still have it somewhere.

IIRC they use a luxeon V emitter which was considered very high output at the time, although it was a physically large emitter so was quite floody. I think 120 lumens sounds about right, I recall it was a huge step up in performance and runtime from the 60 lumen incan bulb.

It definitely wasn't cheap at the time, but it also wasn't the super-premium line. The 6p it was primarily designed to upgrade was a fine light, but only type 2 anodized and wasn't made to quite the same spec as the premium Surefires like the Lumamax line that were also around about that time.
 

Dave D

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Thanks. Ya I figured that's why I snapped it up. Wish it didn't have connection issues though. Not surefires fault they designed it for their light and I have it in a solarforce.
In the past EagleTac Sportac P60 drop-ins came in different bodies for SF or P60 hosts, now they only come in the Surefire shape, but they are now supplied with a ring that can be fitted to the base of the drop-in to allow it to work in P60 hosts. I have just tried the Sportac ring on my SF KX4 head and it works in a Solarforce host.

IMG_7101.jpeg
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vicv

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That's pretty neat thanks. I stretched out my negative spring, made it wider. And works well. It's the positive that has an issue I think. I know and 18650 needs a magnet on the positive to work. But even with that it's still a tiny bit shorter than 2 cr123a but more reliable. Dim though. 2 18650s works great with an extension so it doesn't need a button top. But for some reason two primaries can give me connection issues. I haven't found a way to stretch the positive spring as it just sits over top of a ceramic post. So it just pulls off of there.
 

vicv

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Nice to see those still in use! Not the newest hotness but a decent effort by Surefire to get the old Z/C/P series bodies working with LED's.
Ya. And better thermals than a drop in. I would say an emitter upgrade would be pretty nice, but why bother? Might as well enjoy it as it is.
 

letschat7

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I almost forgot about this. I got it and the LED drop in some time ago but haven't used them. I had an empty 9P sitting around so I'll try it today. So far it seems dimmer that a P91.
 

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vicv

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That's a p60L correct? If so it's about half the output of the kx4, and an even floodier led. So it will appear dimmer than even a p60 let alone a p91. For the kx4, it's definitely not as bright as a p91. Pure lumens might be similar, but the lux is so much lower I wouldn't even try comparing them
 

letschat7

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Yeah unless the batts are almost dead this thing ain't bright at all. Maglite incan smokes it even but perhaps its durable enough to be used on an MP5 or something.
 

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vicv

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Yeah, but I would not consider it to be a weapon light. For that you would want some throw. I guess this would make a good room sweeper? It should definitely be brighter than anything but the biggest mag lights though. Like a 6D Incan would be pretty close if on brand new alkalines. But would obviously throw much much further. This thing was made when LEDs were pretty new though. And they had not even come close to catching up to incandescent yet besides efficiency
 

letschat7

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P90 not P91 I must have switched it back.
 

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