Repair of a Electroviewer 7215 IR Viewer

[_Wim_]

I recently bought a Electroviewer 7215 on Ebay for spares or repair.

I tested the unit (in the dark & also with a pinhole cover over the lens), but I get no image whatsoever.  Sometimes when it is powered down and I remove the lens cap, I get a green reasonably bright spot in the centre of the eyepiece for about 5 seconds. This does not always happen however.  This made me think it power supply related.

The high voltage supply makes a little noise when the pushbutton is pressed. I measured the voltage (with the image intensifier connected), and it measures around -11KV. When reading here on the forum about night vision camera’s, this voltage seems very high, but the voltage does seem stable while the push button is pressed.

The voltage multiplier module is made by VMI (type PS201). Unfortunately, I cannot find any information on this multiplier brick.
Does anybody now this is the correct voltage? Which other test could be performed?

datasheet: https://www.lambdaphoto.co.uk/pdfs/Electrophysics/LAMBDA_EC-ElectroViewer7215-v11.pdf

[Fraser]

Hiya,

Some comments from me.

This is a wavelength converter tube and not an image intensifier. As such it is very low gain compared to a night vision scope, even a Gen 1. The tube used in the Electroviewer 7215 is what is called a Gen 0.
It receives Near Infrared wavelengths at its front target and and drives a phosphor imaging screen at the rear which the user views. It thus converts NIR to Visible light. The p.d across the tube can be around 10kV so that sounds right to me. There were issues with soft X-Ray emissions on poorly designed units but you should be fine with one from Electrophysics.

Due to the low gain of the converter tube, you can operate this unit in normal daylight just like a Vidicon camera. The lens has an IRIS that can be adjusted to prevent overloading and you should not point the unit at intense sources of photon energy within its pass-band as that can burn the tube phosphor. There is little need for a pinhole type lens cap with these low gain units.

When testing the unit, make sure that the IRIS on the lens is open and that you can see through the lens. These units can sometimes be fitted with IR or ND filters on the lens front, rear or even in the units lens mount itself. Such would effectively blind the unit to all but the designed filter response. An IR TV remote control makes a good test source as I am sure you already know

Failure modes on these units are actually quite few. The HT power supply can fail so you get no anode acceleration voltage. You appear to be OK on that front as 11kV sounds healthy to me. The tube can crack (due to impact) or just leak at a sealing point, and lose vacuum. Without a vacuum, internal HV arcing can occur due to the high anode to cathode voltage differential and lack of insulating vacuum. This can cause brief flashes that sometimes appear on the phosphor screen as green flashes but are also visible as blue flashes between electrodes when viewing the naked tube in darkness.

These tubes are very simple in operation. You apply lots of volts to them across the anode and cathode and they just work !

The tube normally presents virtually no load to the HT supply and so the supply is not designed to drive a low impedance. If the tube or its shroud suffer an insulation failure that permits arcing or presents a low impedance to the HT supply, it can collapse the HV and so the tube fails to operate. Look for any signs of arcing at the anode and cathode areas and measure the potential coming from the HT supply whilst connected to the tube. I have seen RTV used as insulation around HT feeds that had broken down over time and arcing to surrounding conductive material followed.

As I expect you know, the >10kV may be from a high impedance source but both it and a charged tube will bite you if they get a chance !

Do exercise a little care around one of these tubes. They do have the potential to generate soft X-Ray.

Fraser

[Fraser]

This page explains Gen 0 tubes.....

https://www.photonics.com/Articles/Image_Intensification_The_Technology_of_Night/a25144

Fraser

[Fraser]

The FJW equivalent unit instructions may be used in the absence of the Electrophysics instructions. They are the same technology but the FJW products are a little more streamlined.

https://www.findrscope.com/product_images/original_images/Downloads/84499X%20Manual%2007_26_07.pdf

Fraser

[Fraser]

A common RCA 6929 IR converter tube, likely very similar to that fitted in your 7215 unit.

I attach the datasheet for an idea of the voltages and currents etc. (Taken from the Valve Museum .... http://www.r-type.org/exhib/aab0087.htm)

Fraser

[Fraser]

Such IR converter scopes are still being made as demand still exists for them for laser work etc....

http://www.ir-viewers.com/product/abris-infrared-viewer/

Manual....

http://www.ir-viewers.com/wp-content/uploads/2017/06/Abris-M-Manual-v1.6.pdf

Fraser

[Fraser]

If your tube is dead, I have a few in a box somewhere in my lab but we would need to see if I have the correct model for your 7215 unit.

Fraser

[Fraser]

There is a matching IR illuminator that may be used with the 7215 when artificial IR illumination is required.......

[Fraser]

Electroviewer FAQ.....

https://www.polytec.com/fileadmin/d/Photonik/Optische_Systeme/kameras-und-kamerasysteme/PH_OS_EPC_EC-FAQ_ElectroViewer7215.pdf

Fraser

[Fraser]

The FJW IR Find-R-Scopes used the RCA 6929 tube so it is likely yours contains the same as options are limited in this market sector. The tubes are available but condition varies. Used tubes can be burnt from their use with lasers etc.

https://www.ebay.com/itm/6929-IR-Converter-Tube-for-FJW-Find-R-Scope-Infrared-Viewer-/184330262394

I have at least one FJW Find-R-Scope head assembly so do have a 6929 tube.

Fraser

[Fraser]

FJW used this version of the tube in cameras with non removable lenses....

[_Wim_]

Wow, so much good information!  I knew I had to post in this part of the forum

This is a wavelength converter tube and not an image intensifier. As such it is very low gain compared to a night vision scope, even a Gen 1. The tube used in the Electroviewer 7215 is what is called a Gen 0.
It receives Near Infrared wavelengths at its front target and and drives a phosphor imaging screen at the rear which the user views. It thus converts NIR to Visible light. The p.d across the tube can be around 10kV so that sounds right to me. There were issues with soft X-Ray emissions on poorly designed units but you should be fine with one from Electrophysics.

Due to the low gain of the converter tube, you can operate this unit in normal daylight just like a Vidicon camera. The lens has an IRIS that can be adjusted to prevent overloading and you should not point the unit at intense sources of photon energy within its pass-band as that can burn the tube phosphor. There is little need for a pinhole type lens cap with these low gain units.

When testing the unit, make sure that the IRIS on the lens is open and that you can see through the lens. These units can sometimes be fitted with IR or ND filters on the lens front, rear or even in the units lens mount itself. Such would effectively blind the unit to all but the designed filter response. An IR TV remote control makes a good test source as I am sure you already know

Very useful information. I was under the impression this was a gen1 unit (because of the S1 stated in the datasheet), but found this already strange because this makes it harder to align lasers in a normally lit room. I have tested my unit without lens cap, but still no image what so ever.

Failure modes on these units are actually quite few. The HT power supply can fail so you get no anode acceleration voltage. You appear to be OK on that front as 11kV sounds healthy to me. The tube can crack (due to impact) or just leak at a sealing point, and lose vacuum. Without a vacuum, internal HV arcing can occur due to the high anode to cathode voltage differential and lack of insulating vacuum. This can cause brief flashes that sometimes appear on the phosphor screen as green flashes but are also visible as blue flashes between electrodes when viewing the naked tube in darkness.

These tubes are very simple in operation. You apply lots of volts to them across the anode and cathode and they just work !

The tube normally presents virtually no load to the HT supply and so the supply is not designed to drive a low impedance. If the tube or its shroud suffer an insulation failure that permits arcing or presents a low impedance to the HT supply, it can collapse the HV and so the tube fails to operate. Look for any signs of arcing at the anode and cathode areas and measure the potential coming from the HT supply whilst connected to the tube. I have seen RTV used as insulation around HT feeds that had broken down over time and arcing to surrounding conductive material followed.

I am starting to think that indeed the vacuum has failed. Will test further on that this evening.

As I expect you know, the >10kV may be from a high impedance source but both it and a charged tube will bite you if they get a chance !

Do exercise a little care around one of these tubes. They do have the potential to generate soft X-Ray.

Thanks for the warning. I did know about the high voltage part (tested with a decent high voltage probe), but the soft X-ray possibility never crossed my mind 

[_Wim_]

I have done some further testing:
no high voltage arcing to be seen (tested in a reasonably dark room), but do get the smell of ozone being generated

I decided to remove the outer layers of rubber, and also the over molded material to check the tube type, but no type is printed on the unit (see picture).  Complete outer casing of the tube is at high voltage potential, no wonder a protective layer was molded on! When tube is placed on my anti-static mat, voltage multiplier makes quite a bit more noise, and voltage drops to 2.4kV just from the minimal load of the grounded  anti-static mat.

Dimension of the tube are:
- 40mm in length
- 35mm in diameter

The black window in the front of the tube is glued on (not removed). No visible cracks in the tube or other damage. The over molded material acted as a mechanical isolator form the housing, I can imaged even if the camera would be dropped (no signs of that on the housing), the tube would easily survive. I can only imagine one of the vacuum seals has leaked. 

[_Wim_]

Forgot to mention, also tested of with 2 IR lasers (850nm and 1064nm), but these were also not visible (so no IR filter installed). Filter in the front of the tube could be an ND filter (looks like that), but without removing it, I have no way to tell for sure.

I also powered the tube up without touching the ESD mat so I had 11kV again, but still no image.

[Fraser]

There would not normally be an opaque filter in front of the tube in a standard unit. It looks like your unit was manufactured for a specific role and a passband or ND filter has been fitted. If your test sources are not within the pass of the filter you will not see anything.

I suggest removing that opaque filter if possible

Fraser

[Cat]

The tube looks more like a Gen 1+ IIT with the fiber optic input but it could be the opaque filter.
Can you take a picture with clear view of the photokathode?

Maybe the tube suffered the same fate like mine, the rust caused a vacuum leak 
When the vacuum is bad the photocathode will get grey or white. The rust might be caused by acetoxy cure silicone.

This is a XX1227 style tube.

A good Gen1+ photocathode has often purple or blue hue. Gen1 are often brown, depending on the photocathode material.

[_Wim_]

The tube looks more like a Gen 1+ IIT with the fiber optic input but it could be the opaque filter.
Can you take a picture with clear view of the photokathode?

Maybe the tube suffered the same fate like mine, the rust caused a vacuum leak 
When the vacuum is bad the photocathode will get grey or white. The rust might be caused by acetoxy cure silicone.
(Attachment Link)
This is a XX1227 style tube.

A good Gen1+ photocathode has often purple or blue hue. Gen1 are often brown, depending on the photocathode material.
(Attachment Link)

That tube indeed looks very similar/identical to mine, and indeed some grey/white is also visible. I tried to remove the front "filter", but it just chips of and I cannot remove it (even tried with some gentle heating, but high heat seems to risky).

As I tested in daylight (which is broad spectrum), even if a narrow bandpass filter was installed, I should see something, but this was not the case.

In which device your XX1227 tube was installed?

[Fraser]

That is a really interesting development. Your latest image provides significant detail. That does indeed look like a later generation of tube than was originally found in these devices. Something that interested me in some sales literature from Electrophysics was the statement that the image was well focussed across its FOV. This is not that typical of early generation 0 and 1 tubes. It provides further support to the idea that Electrophysics moved away from Gen 0 tubes.

I note that the 7215 was discontinued due to the obsolescence of the “image intensifier tube”. That is what Electrophysics / Sofradir state, and the wording “image intensifier” is very interesting. As already stated, these viewers are intended to be low gain IR to VL converters. They are not normally intended to offer the gain of even a Gen1 IIT. The Iow gain RCA tube likely became obsolete many years ago and remaining warehouse stock would be finite. Could it be that Electrophysics used the higher gain later generation tubes in their 7215 to maintain production. It is possible to lower the gain on some later generation tubes but I thought that required a third (bias) connection to the tube.

Sadly, if yours is a later generation tube, I would expect the phosphor to show some life even in a darkened room.

Fraser

[Fraser]

This page has a picture showing the different formats of tubes

https://nachtjagen.com/mo14/content/faq.htm

Fraser

[Fraser]

Nice X-Ray images here 

https://www.ar15.com/forums/Armory/Gen-1-image-intensifier-X-rayed/18-485590/

Fraser

[Fraser]

I have a few Philips XX1332 Gen 2 image intensifiers. I wonder if one of those would fit in your 7215 casing and optical setup ?

They are self contained units with the HT supply inside and only need a few volts to operate.

They come in different conditions and the best sell for crazy money from some sellers.......

https://www.abex.co.uk/esales/optical/philips/image-intensifier/xx1332/0e543_8027_a/index.php

I have not powered mine to test them. I must get around to it some time. I ended up buying complete MCP IIT based Hamamatsu image intensifier systems.

Fraser


Fraser

[Fraser]

The Wiki page on image intensifiers is not bad. It explains the different photocathode materials and the properties of such, along with the generations of IIT.

https://en.m.wikipedia.org/wiki/Image_intensifier

Fraser

[_Wim_]

I found this datasheet listing a whole bunch of tube specifications (to big to attach here):

https://frank.pocnet.net/other/DEP/DEP_ImageIntensifiers_1976.pdf

Based on the mechanical dimensions listed, my tube looks most like a XX1220 or XX1221, but it is 4 mm longer (dimension 'M' is 44mm in my case). But other than that, it is almost identical. But these use an S25 photocathode, and the datasheet from Electrophysics states an S1 photocathode

@Fraser, love those X-ray images of tubes. That is some crazy money for a single XX1332 tube

[_Wim_]

A bit of topic, up until now I have been using a camera with a photonis XX1616 IIT for viewing IR lasers (no specs available for this module, but when I was looking at the site posted by Fraser with the different sized tubes, it made me think of this one again).

The camera was part of an Alcon aberrometer (Wavelight Allegro). A teardown of such a unit is available on youtube:
(from minute 52 the IIT module is seen, this is not a video made by me BTW).

This above camera works quite good, but when the handheld Electrophysics came up for a low price (50$), this seemed like a more practical alternative and a fun little project. 

Items like the Alcon aberrometer are a fantastic source for optical components. The laser and beam expander in the unit alone were worth the 100€ I paid for it. The camera with IIT and other optical components were a very nice extra. 

[Cat]

Nice X-Ray images here 
https://www.ar15.com/forums/Armory/Gen-1-image-intensifier-X-rayed/18-485590/

Oh, someone found my images thought the AR15 thread was dead because last time I searched for it only the first post was displayed

In which device your XX1227 tube was installed?

It was from a Fujinon PS-910 handheld night vision device. The photocathode (not the complete fiber optic) has a diameter of ~19mm and the phosphor output is ~10mm. If I find the tube I can measure the length.