My 519 is generally in immaculate condition, however it’s missing it’s original bezel. It came with what appears to be a standard 500 series bezel, and some aluminum knurled knobs keeping it loosely attached.
I think there were two versions of the original bezel assembly, one with a camera attachment, one without. Tim Koeth’s appears to have a the camera attachment (chronicled here), while the one I saw at Skycraft did not. Check out this shot of his collection – he just may have me out oscilloscope’d. Here’s the shot of the one at Skycraft:
What’s interesting about this one is that the entries for serial, sensitivity, and risetime appear to be blank. A few things to note about the 519 and it’s CRT:
- There is no vertical amplifier. The signal is passed directly to the distributed vertical deflection plates.
- The CRT & shield are typically paired, in part to help protect the CRT.
- The vertical sensitivity and risetime is individually characterized for each CRT at the factory, and is marked on the shield and faceplate. They’re typically on the order of 10v per cm and 350ps, respectively.
- The sensitivity and risetime are marked on the backlit faceplate such that it’s incorporated into photographs, like this
- Because of the extreme speeds that this device operates on, the usable area of the CRT is comparatively tiny; 6cm x 2cm. Compare that with other scopes of the time, which had an active areas of 10cm x 4cm, or 10cm x 6cm.
A little more on that last point. In order to capture extremely fast events in real time, you have to sweep the beam across the screen very quickly. The quicker the beam scans across the screen, the less time the beam spends at any given point, and thus the less energy is imparted onto the phosphor. To get enough energy on to the phosphor to make it glow visibly at these speeds requires tremendous accelerating voltages; 24,000 volts(!) in the case of this scope. The trouble is, the more energy an electron beam has, the harder it is to move it around. This is why the 519 ended up being a 100 lb beast, with sweep generator is driven by a forced-air cooled RF transmitter tube, a relatively dreadful vertical sensitivity, and a minuscule viewable area. Another thing to keep in mind is that while repetitive signals keep sweeping across the CRT face, continuously refreshing the image, this was made to capture single shot events on camera (such as nuclear events), so the beam had to be bright enough to register on film on a single pass lasting less than 50 billionths of a second.
Back to my scope. Here’s what it looks like with the bezel removed
For kicks, I tried installing the graticule from my 551.
That’s not just parallax. The graticule illumination lamps and the notches on the plexi sheet don’t line up.
Remember, this was bespoke machine, only loosely based on the 500 series standards of the time.
Upon closer examination of the CRT shield, I noticed mine is sadly lacking the sticker that proclaims the sensitivity and risetime.
Other examples chronicled have a second sticker above this one with hand marked sensitivity & risetime. I really don’t have the courage to pull the CRT from it’s shield to hunt for any other markings.
I went ahead and drew up a graticule that should fit:
This’ll make it’s way to the laser next week when I’m back in town. Stay tuned!