Know what tubes you are buying!
There are two main types of image tubes that are used in binocular and monocular night vision devices - MX10160 and MX11769. The PVS-7 requires a specific tube (MX10130) that is not compatible for use in the majority of systems so I will be ignoring it. It is important to know which tube you are being quoted or sold because some sellers are substituting 11769's in place of 10160's and not making that clear.
People are buying night vision more than ever before and I've communicated with a good number of guys who didn't know there are two different tube types or which ones they bought. The point of this post is to further educate new buyers to help them make more informed buying decisions.
When you read or hear 10160 (aka F9400 or F9800) the main thing to associate with it is AUTO-GAIN CONTROL. These tubes have a preset maximum gain level and do not have the ability to manually control the gain level such as with 11769 tubes. 11769's have a ribbon cable (aka pigtail) that goes from the image tube to the electronics board inside the device and is what allows manual gain control. 10160's do not. 10160 tubes are primarily used in goggles that do not have gain control however they will function in any device with manual gain control that uses 11769 tubes but the gain control knob will not work. Auto-gain basically just means it dims, or lowers the gain automatically, below the set maximum gain level based on the amount of light entering the tube. Both 10160's and 11769's will "auto-gain" using the automatic brightness control aka ABC. It's a standard feature.
When you read or hear 11769 (aka F9415 or F9815) the main thing to know is MANUAL-GAIN CONTROL. They have the ability, when used in a device with gain control, for the user to manually adjust the maximum gain level (brightness). However, 11769 tubes can be converted to work just like 10160 tubes. This is done by removing the pigtails. It is accomplished differently depending on the tube manufacturer. 11769 tubes are mainly used in PVS-14's or other devices with manual gain control, where the user rotates the gain knob or buttons, which controls the maximum gain level (or brightness). The tube will still "auto-gain" just like a 10160 and will dim or lower the gain below the maximum gain level based on the amount of light.
Modern L3Harris 11769 tubes have removable pigtails. You just unplug them and the tube's power supply takes over and provides the correct amount of maximum gain. Elbit (aka ITT and old Harris before L3 and Harris merged) have their pigtails soldered on. They must be desoldered and the correct flat resistor has to be soldered in place to control the maximum gain. Without the resistor the tube can be ruined or damaged and also if it is done incorrectly. Photonis have their pigtails soldered on. It has been said the pigtails can simply be cut off but I don't know if this is correct and I DO NOT recommend doing that because if it requires a resistor then you can ruin or damage it.
The 100% most important thing that you need to know about 11769 tubes converted into 10160's........both L3Harris and Elbit have stated that their warranty is voided when this conversion is done. It has been rumored that Photonis USA does not void the warranty and I recommend contacting them directly to verify.
WHY THIS IS IMPORTANT
The most popular goggles (RNVG, DTNVG, DTNVS, Mod-3, etc.) do not have gain control and require 10160 formatted tubes. There are other popular goggles that feature gain control and use 11769 tubes (NVD-BNVD-SG, Mod-3VG, etc).
There are MANY sellers using converted 11769's in auto-gain housings instead of actual 10160's and they are not making that clear to the buyers. The biggest issue with this is obviously the possibility of voiding the factory warranty which is typically 2 years. Some sellers claim they have permission from the manufacturers or that the mfg provided them already converted as a substitute for 10160's. Considering that several sources have confirmed with the manufacturers that doing this will 100% void the factory warranty, I would want to make sure that the seller will be able to take 100% responsibility for any warranty issues and provide a replacement if necessary. If the seller closed their doors and you had to contact the manufacturer for warranty, keep in mind the possibility that they might not find any records, and deny your warranty claim simply because it is a 11769 that was converted into a 10160.
Another thing to note is that 10160's are generally better suited for binocular goggles because they are primarily made for use inside Anvis aviator goggles. They have stricter requirements for optical divergence compared to 11769 tubes, which are primarily made for PVS-14 monoculars. Optical divergence refers to the light (or image) not travelling straight after it enters & exits the tube to your eye. This is corrected by collimating the device with the correct equipment which involves turning the ocular lens (or eyepiece) to get the image as straight as possible to your eyeball.
A tube with excessive optical divergence may not be an issue with a monocular but when paired with another tube in a binocular system could cause significant problems. The biggest issue would be the inability to collimate them together, which depending on how bad they are, could produce a terrible image, cause eyestrain, and headaches. I personally believe excessive divergence is not that common based on experience using several PVS-14's in dual bridge configurations but it is possible. The brain does a good job fusing the images from both eyes but everyone is different and some folks may be more sensitive to any differences. Keep in mind that virtually all new tubes being sold by dealers to civilians are mil-spec fall out tubes, which means they failed to meet mil-spec for any number of reasons, one of which could be excessive optical divergence.
If you are shopping for a goggle with auto-gain then you should ask if the tubes are 10160's or converted 11769's. If they are converted 11769's, ask what the warranty is and who will be handling it. You should feel comfortable with the seller and confident with the warranty if it is offered. Besides the differences between 10160 & 11769, there are also differences in the tube part numbers which can affect the tube's specifications. If you are comparing dealers to each other make sure you are comparing apples to apples. Especially when there's a big difference in price.
Do your research, talk to multiple sellers, ask lots of questions, and take your time. There will be no shortage of night vision any time soon although as of September 2020, lead times are increasing due to higher than usual demand for night vision.
With the current buying rush, I expect to see a lot of used night vision flooding the market in 2021, provided that things return to somewhat normal after the Presidential election. If you'll be in the market for a used device and want a warranty, it is absolutely critical to know if the warranty is transferable who will be honoring the warranty. Will it be the tube manufacturer (usually 2 years and tube only) or the dealer/builder (determined by them). If the warranty is through the manufacturer then I highly recommend verifying that the tube(s) are not converted formats and eligible. The most reputable dealers (such as TNVC) let the warranty carry over to the next owner.