Products > Test Equipment
Test Equipment Anonymous (TEA) group therapy thread
Specmaster:
Haha, Mr Helpful :-DD I reckon that could be who a certain Cal lab is employing and when he couldn't find anything on the 3478 to twiddle, scratched his head for a bit and put aside for a while, the following week, picked it up and he'd look again for trimmers etc and gave up and then returned it to me claiming it was uneconomical to repair :-DD
tautech:
--- Quote from: bd139 on May 26, 2018, 08:29:50 am ---
--- Quote from: tautech on May 25, 2018, 11:46:21 pm ---
--- Quote from: bd139 on May 25, 2018, 11:05:03 pm ---This one is hard work ... this evening's shenanigans...
--- End quote ---
You know it'll be worth it !
--- Quote ---Now one really cool thing is the trace is crispier than a crispy thing from planet crisp. Shot in X-Y mode. Not bad for a 42 year old scope:
--- End quote ---
Some centralization adjustments needed. ;)
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The cal is completely shagged to be honest. Mr helpful who fixed it last time decided to just twiddle until it showed something about right :palm:
--- End quote ---
Don't you hate it when some muppet just has to fiddle with the internal trimmers. :scared: :horse:
Oh bugger it's gunna be a bit of a long road but at least the manual is well documented to do a full alignment and when it's done you'll have the satisfaction of having a perfect instrument. The voltage references aren't too hard but the mark time generator can be tougher if you haven't got access to one.
The buddy that gave me my D83 had a 100 MHz Tek mark time gen and I borrowed that to check mine. These days any reasonable AWG should do the trick for timebase adjustments.
If you have all the gear on hand you'd do it in an evening I reckon excepting if you find further faults.
Which is out, the timebase or the vertical amp ? Both ? :scared:
bd139:
Everything is off. I haven’t found anything that is near on :)
I’m going to use my Si5351 synth breakout board for X cal and FG for Y cal on this. I’ll do frequency comp by hand afterwards. The Si5351 you basically tell it a frequency and it generates a clean square wave at that frequency. Once you’ve entered the right calibration constant it’s accurare to 1Hz over the entire range. Neat little IC for £3.
Specmaster:
--- Quote from: bd139 on May 26, 2018, 08:28:39 am ---
--- Quote from: Specmaster on May 25, 2018, 11:20:06 pm ---Excellent work, you will be so proud once you have this completed. Do you think this is one that your Mother might have worked on?
I also secured this just a few minutes ago, of to Clacton tomorrow to collect it, never seen one before but seller swears it works OK.
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Quite possible actually. There’s no signatures on the QA sticker though. Unlike tek :(
Last cal date on this was 1983!
Those are really nice. My father had one. He left the C battery in it though and it dissolved everything.
--- End quote ---
With the possibility that your Mother may have worked on it, whats the plan its finished, retain it as family heirloom?
bd139:
Yep keep and use. These when they are working have the best display quality of any analogue scope IMHO.
Also I have a cunning plan. I’ve been working on a spectrum analyser for about 2 years on and off. This conveniently will fit inside a vertical plugin. So I will disassemble the duff one and reuse it then be able to slide the SA into the vertical slot, plug the sweep out from the timebase plugin into that and use that as the sweep gen for the SA.
The SA is a pretty dumb one btw. It’s basically a dual conversion receiver with two IF’s. The first LO is voltage controlled. Mix with minicircuits DBM. Second mix is SA612. The output is an AD8307. With some cal and praying this gives around 90dB of dynamic range and a sweep span of about 500KHz to 200Mhz and switchable bandwidth of 1MHz for a band scope of 1Khz for measurements which is perfect for HF. Capability is all based on the only helical filter I could get my mucky fingers on.
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