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Test Equipment Anonymous (TEA) group therapy thread

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McBryce:

--- Quote from: 44kgk1lkf6u on September 23, 2024, 04:07:31 am ---What is a non-inverting inverter?  Is it an ordinary buffer?  Or is it what engineers call the Signetics don't gate?

--- End quote ---

Something similar to the bidirectional diodes I have maybe?

McBryce.

dl6lr:
I can supply a TTL compatible zener-capacitor for your amusement. It measures absolutely fine on most capacitor and ESR testers (up to 5V). Borrowed from a non-working horizontal deflection circuit in my Tek logic analyser.

EggertEnjoyer123:
I swapped the hard drive with one of those SD to IDE adapters on my Lecroy 7200A and the scope now gets further during boot.

Unfortunately it seems like I need a computer from the 90s to be able to create bootable floppies for the scope.

Robert763:
You might also need the right version of DOS.
I keep a small collection of old PC's just for this type of thing. Did a bit of R&S kit a couple of years ago. While I had the installation software it installed a bootloader and would only run if the HDD was formatted and booted from MS-DOS 6.2. Not windoze FreeDos or anything else. Fortunatly I also have a collecton of old operating systems..... 

dazz1:
Hi
In 1985 I was at University and learned a method for tuning and characterising control loops using noise and statistical analysis.  I didn't know that a specific item of test equipment was available to do that method, and more.  A correlator is really good and dragging known signals from below the noise floor, and doing statistical analysis in the time and frequency domains.

Roll forward almost 40 years and some how I saw the HP 3721A Correlator on an auction site.  The seller was located only 6km from my home with a low reserve price.  At first I didn't realise what it did until I Google showed me a little information about it, including the operator manual.  Then I realised what it could do.  The manuals are dated May 1971, and for its time, it is a very capable and quite amazing item of test equipment. 

I was the only bidder.

In 1976 the HP catalogue had the price of the HP 3721A  listed at $USD10,125.
To get the most out of the HP 3721A also required the HP 3722A Pseudo-random noise generator priced at $USD3,600 and,
the HP 3720A Spectrum Analyser Display priced at $USD7,265.

In 1971 import duty was about 130% plus the excessive cost of shipping and fees.  This trio of matching test equipment was priced at about the same as a nice house.  Although a government department made the purchase, it seems it could only afford the HP 3721A.  This was an expensive item of test equipment.  I suspect it has only survived for so many years because it cost too much to throw away.

It powers up and the CRT is crisp.  The only concerning thing is that the service manual has the parts section book marked.  The manuals are dated 1971 but other documents show the HP 3721A was shipped to Australia to be calibrated in 1983.  That would have been very expensive. 

The fan mod is ugly but well executed. 

This instrument is capable of a lot of things and learning to get the most from it will be a steep learning curve.

The HP 3721A was sold as faulty.  I need to run through the 22 page performance check to see if it does have a fault.
The performance check and the calibration procedure specify the HP 3722A Noise Generator is required.  I don't foresee any danger of obtaining an HP 3722A under any reasonable circumstances, so I will need to make an equivalent with modern parts.

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