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Thorn MULTI ROLE THERMAL IMAGER EOD 2/89

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NukeET:
I have come into possession of two thermal imagers: an Amber Radiance 1, and a Thorn MRTI MKIII. Unbelievably, and much to my excitement, THEY HAD THE TECH MANUAL FOR THE THORN!!! I suspect this will be of great value to this forum as I could not find duplicate information anywhere. I'm more than happy to provide drawings and technical data from the manual. In addition, I'd like to find a way to get the entire volume up somewhere public, but I'm wary of the legality of doing so. I can certainly provide answers in the mean time. The manual has a complete parts list with schematic diagrams and many of the NSN/NIINs that I looked up are still valid in the supply systems.

Here is what I have done so far:

Connected 24v DC to the battery terminals on the exterior of the device. Device powers on, spins up, regulates speed. Great to hear. I opted to use the external battery terminals over the 3 pin Amphenol input because I don't know the pinout or voltage level of that socket, but have lots of information on external battery terminals. The polarity was painted directly onto the terminals which felt pretty safe.

Investigated cooling air inlet. Unfortunately I am missing the bottle clamp/filter/valve arrangement. I can see some sort of inlet barb sticking out where that assembly would fit over and I am thinking of a way to safely apply high pressure air to it.

I have also gotten a BNC to HDMI converter attached and the device does have a valid video output in this configuration. While I have only static as an image, adjusting all the control knobs seems to have the effect they should.

I also have a VERY robust tripod that came in an olive drab crate covered in Hebrew.

I suspect that the previous user of the device had some sort of semi-permanent arrangement for it as the BNC for power showed signs of heavy use over the battery terminals. I think this is why the bottle mount is missing. I'm sure they had a much larger air source for it, and the tech manual makes mention of doing this as well. This also explains why mine has the remote control and viewing module instead of the man portable configuration.

I'm excited to try applying cooling air, but I am not going to risk anything other than a bullet proof arrangement with 4500 lb air. Not trying to win any Darwin awards here. From what I understand, there is a fairly wide band of adequate pressure, but I have not found reference to a lower limit. The upper limit of the system is 6000 psi.

Voltage limits from the battery terminals are 18v-30v (24v nominal). Mine drew abut 2.5 amps at 24v, but stabilized around 2 amps which seemed a bit high, as the tech manual states nominal 15w power draw for my configuration. (7w for "direct view" which is the man-portable version).

As an aside, shoutout to Fraser for the information on the Radiance 1. The cryogenics in mine work exactly as he describes, but I am not able to get a video output on s-video or otherwise. In fact, it appears all the IO boards are without signal of any kind. No front panel lights, no signal on any of the jacks. rs232 port is dead quiet. Very concerning, but a topic for another thread.

m931:
Hello nukeET.

I have the opportunity to also buy a thorn MRTI MKIII, however if I read your story like this you really need the manual,
is there any way i can get a copy
thank you very much for your reach.

Sincerely.
Coen

NukeET:
Sure, shouldn't be an issue! Sorry for the late reply, took me awhile to see this. I still need to make a digital copy of the manual, but in the mean time I'd be happy to give you any information you are looking for.

Ultrapurple:
I was amused to read this brief article on the MRTI from the mid-80s. It says that "The price of £20,000 to £30,000 for a typical system may limit civilian use" (my emphasis) - for historical context, according to the UK Land Registry the average price of a dwelling in 1984 was around £27,000.

Bill W:
Mind you, around then a P4428 firefighter camera was GBP 7420, and the 'big lens' ones up to £10k

Bill

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