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Oscilloscope in orbit - a pfm diy resource

Discussion in 'd.i.y.' started by martin clark, Jun 9, 2015.

  1. martin clark

    martin clark pinko bodger

    Since we often see threads asking 'do I need a scope and if so, what kind?' here's one I'm going to release into the wild for other pfm diyers to use :)

    A couple of years ago Stevec67 kindly gave me this Telequipment D67 to re-home; MarkW has been playing with it recently, and now I think it should travel a bit further in its dotage. Telequipment was the U.K arm of Tektronix aimed at the service and hobbyist markets. Bandwidth is a useful 25 MHz, has two channels, it has delayed sweep and line-triggering capability (really useful for power supplies) even a Z input - plenty of toys to play with, and the considered controls design of classic Tek gear. Footprint is compact - 225 x 225 x 450mm deep (9 x9 x18") roughly. Comes with mains lead, full printed manual and a basic 60Mhz 1x/10x probe - nothing fancy but good enough to get going. Everything seems to work, calibration is reasonable and I'll give the switches a clean meanwhile.


    As a community resource I propose this toy travels on the honour system - no charge, and no time limits; it's simply your responsibility to get it to the next person by agreement when you are finished with using it. Which probably means arranging a face-to-face meet at mutual convenience - it is quite heavy and think of a scope as a high-end valve amplifier with one non-removable, non replaceable valve: I wouldn't post it!

    So - here it is in Bath and I'm happy to meet within say an hour's radius for first taker. Who'd like a go?


    Current whereabouts:
    22.06.15 Scope is now with grazie - east Kent. Nice to meet you, Graeme.
    CJ14 likes this.
  2. Tony L

    Tony L Administrator

    Superb stuff, I've stuck the thread so it remains visible.
  3. grazie

    grazie pfm Member

    Yes please Martin.

    I should add, I'm more than happy with the provision that this equipment is being loaned. I'll be more than happy to pass on to the next pink fisher, after I've learnt what all the knobs are for and actually used it for a while to help build/repair audio kit.
  4. awkwardbydesign

    awkwardbydesign Officially Awesome

    I've had one for years and I STILL don't know what most of the knobs do! :confused:
  5. Patrick Dixon

    Patrick Dixon Imagineer

    I know what all the knobs do ;-)
  6. Mike P

    Mike P Trade: Pickwell Audio

    Brilliant and generous idea Martin. :)
    CJ14 likes this.
  7. Brian

    Brian Eating fat, staying slim

    Excellent idea and a great learning opportunity for those willing to give it a go.
    CJ14 likes this.
  8. sam_cat

    sam_cat C'est Crounchifique!

    Superb idea!
    I also have a scope I have been pondering what to do with, and would be happy for it to join this one on its journeys.


    I am based just north of Bristol, collection preferred. Its a Hameg HM203-6

    Any interest?
  9. LPSpinner

    LPSpinner pfm Member

    Hi Guys;

    A CRO (Cathode Ray Oscilloscope) can be a useful tool indeed when you need to see rather than hear what is going on. You can usually see allot more on the CRO than what you can hear once you know what to look for.

    For the newbie’s, don’t get to phased about the functions of each control. The panel is broken down into the separate basic functions, Time base or the frequency of the incoming signal, a scale control, which is usually marked Volts per Division for each input, and the trigger, which is what the CRO uses to "lock onto" or synchronise with the incoming signal. All the CRO’s above are a dual trace so there will be two “Volts per Division” sections, one for each input generally both inputs will run off the same time base. The TELEQUIPMENT CRO shown in the first post is a little more high end in that it has two time bases and each trace or input can viewed on its own time base scale.

    The other basic functions are the internal voltage reference or calibration voltage used to adjust the CRO and check the divisions on the screen actually read what you think they read, as well as the focus and intensity of the display and I think these are pretty self-explanatory.Once you look at the function of each group of controls the function of each individual knob or switch becomes a little more logical. I’ve just done a quick check with Auntie-Google and there is any number of tutorials and instructional videos floating about. This one looks good..., but there are many others as well.

    Another useful piece of kit to accompany the CRO is a signal generator or function generator, you can see mine sitting above the CRO in the pictured below. The design was published in a local electronics magazine then sold as a kit through several electronics hobby shops in this country. It was actually very cheap yet quite handy for the general hobbyist such as myself.


    My CRO was also an Orphan that was to be disposed of at my father’s work place. One channel went dead and no one could be bothered to fix it. I did a little bit of poking around, 2 dollars for a new video op-amp on the dead channel’s input and I had a fully functional, Dual trace 50 MHz CRO. I’ve owned it for over 30 Years and its still going strong. Its an old BWD-821, BWD Precision instruments was a local company that folded back in 1993 but allot of their equipment is still going strong. While most of the BWD equipment was technically average it was amazingly solid, very well built and generally built from off the shelf standard parts so not only is it solid, if it does fail it is usually easily fixed. If ever you do need to lift the lid on a CRO's internals be very careful, like and old TV, the Tube uses a high tension voltage which could could electrocute and even kill. :eek:

    I should advise that the Older CRO’s be turned on and left running for a few hours every couple of months or so. The older electrolytic caps, particularly in the High Tension Circuit do like to have their electrolyte reconditioned occasionally.


    PS: You can see on my signal generator that I have re-numbered or re-calibrated the graduations on the Frequency scale, knowing how to use the time base on the CRO and a little bit of maths allowed me to measure the Frequency of the signal generator’s output so I know it is correct.
  10. martin clark

    martin clark pinko bodger

    Thanks for that, LPspinner. Just to add that these days, it is also easy to use software on a laptop to generate tones and functions at audio frequencies. Which reminds me - I'll pack a CD of various test-tones and a BNC-Phono adaptor to go with the pfm D67 :)

    Meanwhile, grazie has first go - once we've worked-out a meet :)
  11. LPSpinner

    LPSpinner pfm Member

    This is very true. A bit of software and a sound card can be a very good function generator and much cheaper as well. Did you know you can also get software that allows you to use your PC as a CRO as well. It not a as cool as the real thing but allot cheaper.:D

  12. sq225917

    sq225917 Bit of this, bit of that

    Nice work gents.
  13. grazie

    grazie pfm Member

    Good to meet you too, Mark. Thanks again for passing on this great bit of kit to me and for fitting me into your schedule for collection.

    Now got it safely home. Turned it on. saw a big dot move slowly across the screen before disappearing, so hopefully that's a good sign that it's still working OK.

    Did nobody take up sam_cat's offer?!
  14. CJ14

    CJ14 Oh not again.

  15. snorbans

    snorbans pfm Member

    The principle of an oscilloscope on loan across PFM is a great idea. I'm doing a 1st recap and have been scouring ebay for one that could be economic. Any chance one of the orbiting models is available?
  16. grazie

    grazie pfm Member

  17. snorbans

    snorbans pfm Member

    I will pm sam_cat. I'm just conscious that post was from June. Its easy to slip up and pick up a conversation in these forums that was actually years ago and the participants long gone
  18. martin clark

    martin clark pinko bodger

  19. snorbans

    snorbans pfm Member

    I'm in Hertfordshire, which is a place easy to get to places from!
  20. cutting42

    cutting42 Arrived at B4 Hacker Ergo


    I have just seen this thread as I have a need for a scope for a project. Is one of them available please?

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