I see you are back for some more photonic goodness. We turn the clock back and take a look at something a bit older. The ITT Exelis PSQ-20A thermal fusion monocular. We saw its latest iteration in the L3 ENVG PSQ-20B. This one is a little different and we dive deep to take a closer look at this version. The Friday Night Lights series is sponsored by ATN Corp, manufacturers of night vision and thermal optics like the THOR LT. As with all of our sponsored series, Friday Night Lights will continue to bring you unbiased news and reviews from a variety of companies.
Thermal Fusion @TFB:
Thermal With The PSQ-20A
So I got a chance to play with the latest iteration of the PSQ-20, the ENVG monocular by L3 last year thanks to my friend Jason K.
But did you know there are other versions of the PSQ-20? I recently acquired this PSQ-20A and just like the PSQ-20B there is not a lot of information about them.
From what I have seen and been able to confirm from other night vision enthusiasts is that there are two more versions of the PSQ-20. Below is one made by Exelis according to the MFG ID Code.
Photo by Tony Z. Rear of the L3 PSQ-20A
Photo by ITT Exelis from Half-Mast & PS Magazine
Then there is this other variant of the Enhanced Night Vision Goggle below. I am unsure as to who made it and have not seen another one like it. This belongs to my friends at Last Shadow and I think it is made by Leonardo DRS.
Other than the newer PSQ-20B by L3, the PSQ-20A variants all seem to have a similar design. The battery pack attaches to the top of the unit which is also where the goggle attaches to a proprietary power mount. Also, the PSQ-20A positions the thermal objective lens below the night vision objective lens.
Closer Look At The Exelis PSQ-20A
This unit came with an ACU padded case and two different battery packs.
The bigger battery pack holds 4xAA batteries while the smaller one just holds 3xAA batteries.
Just like the newer PSQ-20B, the PSQ-20A battery packs attach to a special mount attached to the back of a helmet. The larger 4xAA battery pack is similar in concept to an ANVIS battery pack. There are two pairs of AA batteries and a switch on top to select each bank. Throw the switch to the left or right to use their respective 2xAA battery banks. Move the switch to the middle and it shuts power off to the goggle. Just behind the power switch is a funnel-shaped release. Pull up and you pivot the battery back off the helmet.
The 3xAA battery pack does not have any power switches. Just attach it and it delivers power to the goggle.
It does have the same release mechanism as the 4xAA battery pack.
The helmet mount has four contact points that correspond with the battery packs.
While the PSQ-20A has 6 contact points. I am not sure what the extra two contacts are used for.
The battery packs can be attached directly to the PSQ-20A. There is no onboard power for the thermal fusion system other than piggybacking the battery packs.
PSQ-20A Mount
The mount is made by Norotos and has similar features and design as their INVG mount.
The only difference between the PSQ-20A mount and the INVG is the shoe and power contacts as well as the power cable. 
Turn that release lever and you can adjust the pupillary distance by sliding the shoe left or right.
That threaded rod is what holds the shoe in place. Unscrew it and you can swing the shoe to the other side for use with your left eye.
You have to be careful with this power cable. I have had it get caught on the tilt adjustment lever just above it as I try to flip the mount upwards.
The lever on the right side of the shoe is how you release the PSQ from the mount. You have to push the lever inwards and then pull it down to release the PSQ.
Height adjustment is controlled by this threaded rod. Turn it to raise or lower the mount. At the bottom of the photo below, you can see the release lever that allows you to slide the mount forwards or backwards.
Just like the INVG, the PSQ mount can flip up against the helmet. The triangular-shaped horn can spin to bring the monocular closer to the helmet for more comfortable stowage as well as preventing the user from hitting the monocular on things like getting in and out of vehicles.
Rotating the monocular to the right is straightforward however swinging it to the left is problematic due to the release lever that allows the mount to slide forwards or backwards. You can see how it hits the height adjustment knob.
If you want to swing the PSQ to the left, you need to slide the mount forward, flip the horn up and then rotate the monocular to the left.
Unless you are using the PSQ-20A on your left eye, there is no real reason to rotate the monocular to the left. As you can see below, the monocular sits much closer to the helmet when rotated to the right.
Below you can see the mount removed from the shroud. The shroud only attaches to ACH-style helmets using a single bolt. See the four contact points on the shroud and mount? That is what delivers power from the battery pack mounted on the back of the helmet
The PSQ helmet system uses a flat ribbon that runs underneath the helmet between the pads and helmet shell.
Aside from the contact points, the shroud is modified to allow clearance for the cable that routes power to the shoe that grabs the monocular.
Operating The PSQ-20A
Just like the ENVG PSQ-20B, the older 20A has an I/O port. I do not know what systems this can support as augmented reality like ATAK is rather recent. Perhaps this was for future development but was never supported thoroughly?
The objective lens infinite focus stop is a simple stop machined into the housing and fine tuned with a small grub screw.
Spin the objective lens the other way and it stops against the housing.
Just below and to the right of the objective lens is the power switch and gain control for the image intensifier. You can push this switch in to change settings for the thermal.
On the back of the housing is the switch for the thermal. Just like the image intensifier switch, this turns the thermal on as well as controls gain. It is also a push button for choosing different settings.
On the opposite side of the thermal power switch is the IR illuminator switch.
Push the IR illuminator switch clockwise and that is momentary activation. Rotate it counterclockwise and the switch will lock in place giving you constant activation of the IR illuminator.
The IR illuminator is the dusty circle below. I think the other one may be a light sensor.
As mentioned earlier, the image intensifier switch and thermal switch are both push buttons for changing options and features in the thermal. The buttons have different functions when the night vision is on or off while the thermal is on.
Night Vision OFF/Thermal ON pressing the front button will digitally zoom 2X. Pushing it again will go back to 1X magnification. Pushing the back button will switch between white hot and black hot. Pressing both buttons simultaneously will calibrate the thermal.
Night Vision ON/ Thermal ON pressing the front button will switch between Full Thermal, Overlay and Outline. You lose the digital zoom feature of the thermal unless you turn the night vision off again. Pushing the back button will still switch between black hot or white hot and pressing both buttons simultaneously will activate calibration.
The overlay mode is sort of like patrol or half mode seen in COTIs. Below is an example of outline mode.
Outline mode
What is strange is that the thermal image is a sort of reddish-brown color or dark orange but the outline mode is white. The white outline mode reminds me of the COTM on my PVS-21. Below you can see full thermal black hot.
White Hot Overlay
There is a person walking about 30 yards away.
The same person about 50 yards away now in outline mode.
Thermal boot up screen without night vision turned on.
Just like the ENVG PSQ-20B, the PSQ-20A can operate the thermal independently from the night vision. A boon to the PSQ fusion monoculars over a COTI system since the COTI needs the night vision in order for you to use them. You can use the COTI eyepiece or hold the periscope uncomfortably close to your eye and see the thermal image with your naked eye but that is less than ideal. I am not sure if this unit is bad or if this is typical for the ITT Exelis PSQ-20A but you can see how low resolution the thermal image is.
This video on YouTube is what I was expecting. This looks similar to the ENVG PSQ-20B that I reviewed except it was white phosphor and did not have those segmented brackets at the corners.
Here is a video comparing the unknown PSQ-20A (possibly Leonardo DRS) to my current PSQ monocular. I briefly got to look through when I was waiting to shoot at night with Last Shadow back in March. I recently used the PSQ-20A in a nighttime corn maze just like I did last year with the ENVG PSQ-20B.
Inside The PSQ-20A
When I had the ENVG PSQ-20B, I wanted to peek inside but since it was not mine I did not attempt it. Not the case here. Just like the Northrop Grumman Mark VII, I opened this PSQ to take a peek inside.
The first thing I did was remove the eyepiece to take a better look at the rear projection. Unlike a COTI, the thermal image is projected on a beam splitter behind the image intensifier.
To my surprise, the eyepiece is extremely compact.
Here is the thermal projector with the thermal turned on.
See that transparent window sitting over the image intensifier? That is where the thermal image is projected.
So I decided to explore more. The rear housing is held in place with just a few screws. Once removed, you can pull the rear housing off. To my surprise, the rear housing looks and feels like it is made of plastic but that is only a coating. The housing is made of metal as seen below.
You should be careful removing this rear housing since there are buttons and switches that are on the rear housing and they plug into the front section.
With the rear housing removed, we can see some interesting information. ITT used F9816YG tubes. 98 signifies green phosphor and YG is a designation for mil-spec tubes. I am not sure what the 16 is for but 15 is a standard designation for manual gain on an 11769 tube typically used for PVS-14s. The PSQ-20A does have manual gain. You can see some dates and they look like the date of manufacture.
Below is an old tube I got that has an odd manual gain ribbon. I was told it might have come out of a PSQ-20. Notice the logo? That is Insight Technologies. While this is not the tube that is in the 20A, it might be similar since I have never seen another tube like this in standard manual gain systems. The PVS-31 tubes have a different design.
I am not entirely sure what I am looking at but that part that sits above/behind the image intensifier is the projector to display the thermal image. The rest must be the thermal detector and the chips to process the image.
Final Thoughts On The PSA-20A
The PSQ-20A is a cool piece of night vision history. The newer ones are better and this one does not seem to age well. That is due to the rapid evolution of thermal technology. It is my understanding that the PSQ-20s were sold for around $20,000 back in the day. Compared to modern thermal systems, this is a massive waste of money. I did not pay nearly that much.
Just like the ENVG PSQ-20B, this PSQ is a bit cumbersome. It is smaller than the L3 version but it still requires remote power or a massive battery pack docked onto the goggle. I prefer the newer L3 variant since it positions the night vision objective lens under the thermal objective lens. This makes it more ideal for passive aiming. Not the case here. Since the thermal objective is at the bottom, it will detect things below it sooner like the top of your rifle and your hand or a suppressor.
One day I may feel adventurous and upgrade this to white phosphor but for now, there is no need.
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