Author Topic: Tektronix 2400 series scope U800 drop-in replacement  (Read 319 times)

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Offline Jwalling

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Tektronix 2400 series scope U800 drop-in replacement
« on: June 13, 2020, 05:28:12 pm »
Saw this on the Tekscopes@groups.io for you guys that are still playing with antiques. A drop-in replacement is being developed for these that has X-Y mode capability (Unlike the Thomas Lafay replacement)
Jay

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Offline Jwalling

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Re: Tektronix 2400 series scope U800 drop-in replacement
« Reply #1 on: June 13, 2020, 05:30:28 pm »
His reply to some questions:

Quote
Dear folks,
Thank you very much for the encouraging responses and questions. I will indeed keep you posted on the progress as I take it to manufacture.  I am planning to launch this for sale by the end of Q3 2020. The PCB layout and design are in the third iteration and this video was essentially the result of my attempts to fine-tune the performance to an acceptable level before finalizing the design and layout. Of course I do not claim it works as well as the original U800 but the hope is that you find this useful enough to allow you to stow away the original for a rainy day and use this replacement board on noncritical occasions.

1. "Will it pass the CAL01 procedure?" From what I can see, as long as the same adjustment controls used in CAL01 continue to work with the replacement board, you can carry through the procedure to completion. And that was the aim, which is why the "drop-in" tag. The only adjustment that the current prototype in the video does not have is the "TRANS RESP" trimmer but the next version of the PCB has it.

2. "Is this an updated version of the Thomas Lafay implementation? Or a new design entirely?" I was indeed inspired by the magnificent effort by Thomas Lafay. However I had some difficulties when I tried to get it to work, and I felt a more comprehensive and at the same time a more compact implementation was possible. Conceptually of course they are very similar - I cannot claim my design is "entirely new". For example I used the same transistor topology as in the Tek 2232, which the Lafay design also did (though the transistors themselves are different). However there are important differences. Foremost, it attempts to provides all of the functional modes - including XY which is not in the former. Secondly, in doing so, it makes use of all the adjustment controls on the main board itself. Thirdly, I found that the 500ps/div needs special attention  - which is why you have a TRANS RESP trimmer on the main board to specifically adjust the gain of the 500ps/div mode. My design adds a few extra smarts for get the 500ps/div speed. The layout is of course completely different - the Lafay implementation is a much larger PCB which needs you to replace a few parts on the main board to be able to accommodate it.

But again, many thanks are due to Mr. Lafay for the original effort and the inspiration!

Best - Ram
Jay

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Offline Galen

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Re: Tektronix 2400 series scope U800 drop-in replacement
« Reply #2 on: June 14, 2020, 07:35:06 am »
Really good news.
Another easy-broken part of the Tek24xx is the U400.
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Online tggzzz

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Re: Tektronix 2400 series scope U800 drop-in replacement
« Reply #3 on: June 14, 2020, 09:15:37 am »
Really good news.
Another easy-broken part of the Tek24xx is the U400.

Yeah, I've had to replace one of those.

There is a sgnificant difference, though, U400 is easily removed/replaced, but it is difficult to fabricate the correct form factor.
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