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Does anyone have any design specifications or technical information on the CRT used in the Tek 576 CT ?
- anyone have Xray images of that tube ?

I understand for the many posts in Groups io that it was a "special" crt tube,
but looking for technical details to attempt to kludge -swap in- some other CRT,
in place of my dying 576 crt tube....
thinking there must be some way to do this in some fashion.

thanks,

There are videos out there on Tek's CRT production line. They are very interesting. With
sufficient resources you could probably duplicate a tube, however it would be cost prohibitive
(you'd also need a complete machine shop, glass shop, ceramic setup and high vacuum lab,
among other things). I daresay going through the learing curve would take a few years.

There are hobbiests that make their own vacuum tubes though, so there is that.

The way to address this today is to digitize the signals and use a microcontroller to write
the display to an LCD panel. (You could also just tap out the signals to an XY display if
you wanted to stick with a CRT and use an overlay with the grid on it).

Because most of the controls have contacts to display the values along side the screen, you can
also tap into those and have your microprocessor do various calculations for you on the fly.

IIRC, there was someone about a year ago who advertized a product, might have been a kit, that
converted a 576 to a wiz bang computer controlled curve tracer. I looked at it at the time, but
it was too pricey for a cheap hobbiest like me. I ended up getting an actual computer controlled
Tek curve tracer (a Tek 571) which does most of what I need to do although it lacks the super
wizbang features. I got that for a few hundred.

There's probably space for a simple minded display replacement that would duplicate the 576 CRT
display without adding all of the other stuff. I think about that from time to time, but it's
not high on my project list. The problem is, once you have a processor involved, it's hard
not to do everything else.

Paul

--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@... | Linux/Unix - We don't do windows

Possibly the 5ADP1 crt, as suggested by Walter.

Rick,

I echo what Paul says. One thing you can do is look for a donor 576. As you know from reading through the messages, the older 576's have issues with the HV (brown) transformer. I got one of these and had a replacement HV transformer professionally made. The CRT is bright and sharp and appears to have low hours.

I have a theory that the ones with HV transformer issues will have low hours on the CRT, as the HV transformer issue is difficult to troubleshoot and usually only shows up when the transformer has warmed up a bit. I would have never guessed or thought to look at the HV transformer with out the help of this group (and some members of this group that have moved over to Tekscopes2). So my theory is, the older 576s developed an issue with the HV transformers, and service was attempted (unsuccessfully) and then put on the junk pile or relegated to a back closet somewhere.

If you keep an eye out on eBay (high priced mostly ... but not always ... you can have eBay email you everytime a new 576 listing shows up) and other places (craigslist, facebook, swap meets, etc) for ones with the brown transformer and really beat up, you can get a donor at a good price (less than the kit mentioned a few months ago), plus you will get some other parts too. I agree it is still a risk the CRT will be well used or damaged, but the two "brown transformer" ones I have gotten have really good CRTs)

I hope you find one.

Dave

Another option is to increase the CRT filament voltage. The easy way is to set the mains voltage selector to LOW.
Since the CRT filament is powered directly from the main power supply transformer, this increases the filament voltage enough to often cause a significant increase in intensity.
This will also increase the the voltage regulator dissipation, but with the large heatsink of the rear casting, this is not really an issue.
Be aware that the CRT filament is raised 3KV above ground.

There are few options for an excessively weak or dead CRT in the 576.
Years ago I had considered attempting to install a CRT from the 1420 or 528, one without an internal graticule. These are at least somewhat similar in physical size, although smaller, and use a similar low HV.

Good Luck with your effort.

This subject has been discussed many times over the years. A short answer is that the technical aspects of the CRT are quite modest in terms of speed (and therefore operating voltages), and the only thing "special" about it is the 10 x 10 division graticule on the screen, versus 10 x 8 commonly used in scopes. It's the same basic CRT as in some other Tek models except for that. Years ago I figured out the models that have the right CRT, but I forget which - I think it is certain 5000 series scopes and 600 series XYZ monitors. I reported on this here some years ago, so the results should be possible to find with some searching. I think it was around five to ten years back - I had a possible different CRT sub selected, but didn't need it yet since I did a successful (enough) rejuvenation on a 576's original CRT.

The simplest fix then is to just put in one of the alternative types, and tweak it up to register properly with the 10 x 8 graticule. The 576 original has the 10 x 10 square plus two extra horizontal divisions marked with dotted lines, which kind of help to fill in the classic 4:3 aspect ratio. The scope equivalent is 10 x 8 larger divisions. So, you get a bigger picture, but less vertical range on screen. As long as the deflection system is tweaked up to match, it will still be right, just a little different in appearance and operation. For instance, there will be only 8, not 10 on-screen vertical offset steps. You can adapt to the differences with use - it's way better than having no 576 at all.

Ed