CA4810A Curve tracer

[jord4231]

I've been eyeing off one of these Chinese curve tracers for a while.
I know its not going to be comparable to a Tektronix or HP.
I had it in my watch list for a while and this morning the seller offered me a $200 USD discount.
This is a new item (but when questioned he didn't have test fixtures for it) I guess I'll be making some.
I'm concerned about the CRT in shipping but after a chat with feebay I have "eBay Money Back Guarantee" on this item.
Fingers crossed..... still slightly shitting my self 

I plan on doing a youtube review of it when it turns up and will post a link to that.
If your interested the link to my chan is here https://www.youtube.com/channel/UCcfLsPu5m6QQ4KzBC1uTlZQ

[TERRA Operative]

Intriguing.
Looks like a clone of the Tek 576 or 577.

I'm interested in what its stated specs and real-world performance is like compared to the Tek units.

[jord4231]

When and if it shows up in good condition, I will do a full teardown any tests anyone would like to see please post them here and I will make a video around it.

[jord4231]

Here is a higher res version of essentially the same thing

[RoGeorge]

Looks like a Tektronix by the box shape, yet the panels are different.

W2AEW made a couple videos about using a Tektronix 576 curve tracer:

[jord4231]

I just watched both of them this afternoon thanks 👍

[jord4231]

I have some good news. It arrived and it works!
I will do a video overview soon!

[mawyatt]

Very interesting!!

Have you taken a look inside, and if so how's the build quality?

Anyway, hope you time to post details and possibly images.

Best,

[jord4231]

Working on a video now with a teardown I'll post it when it's done.

[David Aurora]

The suspense is killing me on these vids man! I was looking at these earlier in the year and close to taking a chance on one, but ended up going with a 576 (which was a fucking saga, but that's a whole other story and thankfully sorted now). I'm still super curious what they're like though

[pope]

What's the price for it?

[jord4231]

The suspense is killing me on these vids man! I was looking at these earlier in the year and close to taking a chance on one, but ended up going with a 576 (which was a fucking saga, but that's a whole other story and thankfully sorted now). I'm still super curious what they're like though

I did see your post a while ago with the broken crt thats horrible I feel for you!
What did you end up doing with the unit with the broken screen?

I hope to start working on the video Saturday if there is any specifics you want me to look at let me know!

[David Aurora]

The suspense is killing me on these vids man! I was looking at these earlier in the year and close to taking a chance on one, but ended up going with a 576 (which was a fucking saga, but that's a whole other story and thankfully sorted now). I'm still super curious what they're like though

I did see your post a while ago with the broken crt thats horrible I feel for you!
What did you end up doing with the unit with the broken screen?

I hope to start working on the video Saturday if there is any specifics you want me to look at let me know!

In the end it actually all kind of worked out. Ended up keeping the broken unit after working out a deal with ebay over it all, and then miraculously managed to get my hands on a replacement CRT from the Tek museum. In a way the damage was a blessing in disguise because I couldn't put off the digitisation system I had planned to build for it, it was the only way to use it for a while there (even just for testing to see if the unit worked at all while deciding what to do with it). So yeah, now I have both a working screen plus external connections to the computer for it so I can save measurements super easily too. Also built a bunch of accessories for tube testing to go with it since so that's taken a bit of spare time too, but the whole rig is basically done now



No real specifics I can think of, just curious at the overall operation/build quality really! It's probably quite easy to connect up the way I have too, and I may have use for a second setup like that in future so it'd be good to work out if one of these could be an option rather than the nightmare of getting another 576 to Australia!

Have you looked into the HV fixture for it at all? That was one of the other things for me- I needed the ability to go a fair bit past 500V

[jord4231]

Hi David,
I have not looked in to the 500v test fixture yet.
It would be a nice to have.
I will be looking at making my own test fixtures in the future as this unit came with none at all.

I'm glad it all worked out in the end. I'd still love to own a Tek one day.

I would say that internally this is not as advanced as a Tek 576, I would feel confident that if this failed (except for the crt) I'd be able to fix it.
At a first look it looks to have fairly straight forward components, no odd ball ic's that I have found so far.

Anyway I will have a detailed look at the boards and insides in the video. I hope to finish it off tomorrow, We have just had a crazy rain storm and quite a lot of flooding (this has slowed me down a bit) luckily the lab is ok.

[jord4231]

Put together a video of the curve tracer today, Mainly showing the insides.
I really need to make a few test fixtures for it as I have none currently.
I might make up one up for tubes too.

In the future once I have made some fixtures I will likely make a part 2.
If you have any questions or anything you would like to see in part 2 let me know.
Cheers
https://youtu.be/1vBecCaLePk

[mawyatt]

This Curve Tracer doesn't look very well made, lots of sloppy assembly and attention to details. Makes one wonder about the actual design, and agree it should be relatively easy to maintain but seems destine to early failure by the looks of things you've uncovered!

Might be interesting to see the actual waveforms utilized for testing, if you have the time could you hang a scope on the collector and base? Suspect the Collector waveform is a scaled Mains line voltage and the Base steps are synched to the Mains. Also, an easy verify of the relative accuracy of the knob & scale settings and actual applied signal, one can use a precision resistor as the DUT.

One thought, since the warranty isn't likely worth much, would be to tap into the Sweep (Collector) waveform for X axis and Current referenced waveform for Y axis for external output to a DSO so one could capture screen shots from the DSO, or better yet a digitizer for X and Y axis for post processing with a PC or Raspberry Pi. We've already seen some folks creating some really nice Curve Tracer plots, so thinking the CA4810A could be adapted for such!!

https://www.eevblog.com/forum/testgear/show-us-your-curve-tracer/

https://www.diyaudio.com/community/threads/intelligent-curve-tracer-3-0-release.205733/

Anyway, nice video and thanks for taking the time to post

Best,

[jord4231]

I would also suspect the collector and step gen are derived from the AC mains, there are two controls looping and compensation it will be interesting to investigate these and check out the waveforms. I will do this in part 2

As mawyatt said the attention to details / assembly are sloppy, with high voltages present this can bring safety concerns.
I wonder if the ST branded parts are fake (probably)

Digitizing X and Y with a Raspberry Pi sounds like a great project I'll add it to my to do list.

A Eevblog member asked if I would purchase this again.
My answer is it depends...
If you are looking to put this in to commercial use I would look at something better.
If you are a hobbyist and love modifying things and are prepared to fix it when it fails AND you can get it for a decent price go for it.
Truth be told one of the reasons I purchased it was to look inside it and make a video!

Depending where you live you might be able to find your self an old Tek curve tracer but then again you might need to put some work in to that too!
In Australia IF you can find an Tek the price is just bonkers.
I found one in Australia listed on ebay a few years ago for $1000 buy it now.
Still kicking my self I missed it by a few seconds. It was listed for less than 2 hours before it sold.
Then there is the risk of importing one.
One day I will find one.....

With the CA4810A I was covered with buyer protection, I was also curious how that was going to pan out if needed.
At one point when I received a notification the box label was unreadable I thought it was going to be smashed for sure!

Anyway thanks for the comment and thanks for watching the video.

[David Aurora]

Looks about as expected overall, though I was surprised to see the simultaneous display of both DUTs, that's pretty cool. I couldn't really see, is there much control over that feature as far as positioning/switching rate? Any noticeable effect on measurements in that mode?

As far as the digitising thing, the easiest way I found for the 576 was tapping off the deflection plates via a little adaptor circuit I built up to attenuate and offset. I tried a couple other things but doing it this way meant that I can move stuff around with the curve tracer display controls and the digitised version will always match what I see on the CRT. The only catch is that you need to tell the software what the range is any time you change vertical/horizontal settings as the digitised signal is always just a scaled display (in other words, the digitiser never sees a 0-1V or 0-1000V or 0-500mA signal, it sees whatever voltage it takes to drive the CRT from 0-10 divisions regardless of your test voltages/currents). Obviously if you could be assed you could set up auto range switching with a bunch more wiring and code, but so far I just save templates with the correct ranges for parts I test the most.