Tektronix TDS 1002 DSO (Digital Storage Scope) Examining FFT Function At Audio & Radio Frequencies.

[@timrobertson100]

Thanks for taking the time to post this. One has come up for sale locally, and your video answered all my questions nicely.

[@UncleBensRice]

Hi David first of all I really love your videos and enjoy them. I like your idea of using a Dso for spectrum analysis, I never thought about that since my own Dso won't go down to the audio range. Also for my normal work I tend to use my Tektronix 475 instead of the Dso. I'll definitely take alook for one of these Tek Dso's and maybe pick one up. Have a nice day and greetings from Germany.

[@ElPasoTubeAmps]

+Uncle Ben's Rice Actually, I never thought about using a FFT device for audio either but this is really promising. I just quit playing with it and it is amazing me with all the features it has. A 475 is a nice high-end scope and I don't think this DSO will replace it but I think it is going to get used in my shop quite a bit. This video was certainly quick and inadequate so maybe when I really get used to it I can post some more of its features. Thanks for your comments.

[@ElPasoTubeAmps]

+Uncle Ben's Rice I did have an opportunity to work with the FFT function today and study the manual. I am impressed with this instrument. I have compared as best I can, the FFT display with my HP 3580A and they closely agree at 1 KHz and up At low frequencies the HP is so slow and difficult to work with I did not make any serious comparisons but the Tektronix instrument gave me a pretty quick display that I had no issue believing all the day down to ten (10) Hz. I think it is OK and likely a much better investment than some unknown 3580A that is approaching forty years old and a CRT display (and associated HV circuit problems). I did find that it was a good idea to use a 10X probe so as to not overdrive the vertical channel.

[@UncleBensRice]

+ElPaso TubeAmps I would love to see a comparison between the Tek running FFT, the Hp 3580 and maybe even the 7L5 in the case you still own that plugin. I nearly brought a Hp 3580a 2 days ago on ebay. Luckily the price went quite high so that I didn´t place my bid on that unit.

[@ElPasoTubeAmps]

+Uncle Ben's Rice I sold the 7L5 some time back. I love Tektronix instruments but their spectrum analyzers are just not as good as the HP's in my opinion. On the other hand, I wouldn't have anything but a Tektronix oscilloscope.

[@TheSoundtec]

I noticed your display looks inverted white on black background? Is this a function of the TDS1002? Thanks Great Video!

[@ElPasoTubeAmps]

I think that can be changed but I am not sure since I haven't used it in a while. Thank you.

[@bendec2969]

David, do you still use this Tektronix FFT? I have an opportunity for a nice price on a similar model and I'm wondering if it is something I should pursue based on what might be available today. I do currently have a Siglent SDS1202X-E which is OK but cumbersome. It isn't really very spectrum analyzer like. I think the Tektronix has a more spectrum analyzer interface with span and center freq etc.. Let me know if you still prefer/use this device fof FFT audio analysis... I'd love to hear you opinion. Thanks Ben,

[@ElPasoTubeAmps]

Here are my thoughts and why I bought it. I wanted a first class audio SA - the specs go down to audio ( I think.. but these RF type of SAs are not the best for audio. In addition, true RF SAs are 50 ohm input. That will load your 8 ohm output and is just a bad fit. The little Tek SA is high Z input and does work as expected of Tektronix equipment, but if you are wanting an audio SA, the PC based ones using a USB sound card is much better. You can probably use the built in mic input on a PC but you will need an outboard attenuator - you will need the attenuator for all of them. I think the single channel, Scarlet Solo by Focusrite does a great job. As I assume you know, there are two types of spectrum analyzers - the HP 3580A is a jewel and is, swept-tuned, type of SA. Does a great job but if you are looking at low audio frequencies it is painfully slow in tracing out the spectrum. Its noise floor is -90 dB. More on that in a second. The FFT audio analyzers that work with a PC are much faster and you can actually adjust the filament hum balance and see it change dynamically with the FFT analyzers. You can not do that with the swept-tuned units like the 3580A. The FFT analyzers display a noise floor down at -140 dB but that is completely unreal. The difference between -90 dB (which takes the very best interconnecting cables and a very quite lab) and the -140 dB floor of the FFT analyzers is 50 dB, a factor of 100,000 - it is not real and I can't even imagine an environment with a noise floor that low. I hope this is helping. I rarely use the little Tek DSO 1002 scope. It is handy sometimes. There are a number of free download audio FFT analyzers you can try. One is ARTA, another is SpectraPLUS and TrueRTA, which if you buy the license will put your name and data on a very nice harmonic profile printout. Google them and see what you think. spectraplus.com/Downloads.htm I think ARTA went out of business. SpectraPLUS is very expensive but you get 30 days free to evaluate. I use TrueRTA and my 3580A and they both give me essentially the same display.

[@bendec2969]

@@ElPasoTubeAmps As always thanks for the in-depth response... It is helping me decide... Soon I will reach out with some questions against another of your videos regarding biasing for a variety of tubes in the same amp, specifically EL34 and 6L6... But I'll get to that later. Have a great holiday.. Thanks Ben.

[@djfrank59]

Hi David! Interesting scope! it's nice and light to carry around. The only thing is, in all honesty, For amplifier repair and for working on vintage tube electronics as I do, I honestly prefer a CRT scope. I like looking at signals in real time. These new scopes are constantly refreshing the display. It's just a personal preference. But I do see some other good uses for this particular scope in the digital world. Either way, it as a good score for the money! Always enjoy your videos. :)

[@ElPasoTubeAmps]

+Frank Ferraro Hi Frank - I have played with it enough that I have confidence that it will tell me the truth about audio harmonics, actually going down to 10 Hz with no effort. I cannot reproduce those low frequencies on on my HP 3580A. I am still getting a grasp on analog SA's vs FFT devices and what I have read so far don't prefer the FFT's over SA's.. On the other hand, I just watched a video that praises the FFT. In any case, I am not going to get rid of my 350 MHz analog scopes anytime soon.

[@UncleBensRice]

+ElPaso TubeAmps The first scope I ever brought was a digital Rigol oscilloscope, but it has been replaced by a analog Tek simply because it gives me the better "realtime feeling". Its nice to have all the capabilities to measure or store waveforms, but for a repetitive 1 kHz sine wave I really don't need them. If I wan't to measure RMS Volts I'll hook up my Fluke.

[@Ziplock9000]

I agree. Most audio level engineers still prefer analogue scope. RF engineers too.

[@NepsysHypertunia]

I'll get to use it.

[@EJP286CRSKW]

The FFT must be in log Y mode with about 120dB full scale to be able to show the THD of an SG505. BTW did that really say 70V P-P? From an SG505?

[@ElPasoTubeAmps]

+QuadMaestro Good point about the SG505. My devices are only 80 dB so they are not the true quality of the SG505 at 8 ppm THD.. I did say 70V P-P but I corrected it with a speech bubble mentioning that I had the scope configured for a 10X probe when I was direct connect at 1X. I want the Precision Audio equipment so I can go -120 dB but the noise level at my work bench seems to negate that plus my lack of a $$$ wallet. Always appreciate your thoughts.

[@FelinoAnticomunista]

Only gray lcd color ???

[@ElPasoTubeAmps]

This a small and inexpensive one.

[@DAVIDGREGORYKERR]

I think EEVBLOG did a teardown of this scope, there is a scope that costs around $20,000 dollars and is totally software based as it uses a customized version of Windows XP Pro, it is a shame that the scope that you are looking at did not use the A10-7800 for data processing and display of the signals on the screen.

[@ElPasoTubeAmps]

+DAVID GREGORY KERR I saw that EEBlog tear down . Actually, I did have to disassemble this unit and repair a little plastic retainer on the CH 1 gain control. It came apart very easily and went back together easily too. I think we all dream of the $20K MDO devices but they will not be used-affordable for another 20 years. I doubt I will need one that long from now :-)

[@EJP286CRSKW]

I'm now wondering how this Tek compares with your FFT software ... :-)

[@ElPasoTubeAmps]

Good question. First off, the Tek is a 60 MHz oscilloscope and it has the math function of FFT as a secondary function. It works great but it does not come close to the FFT software and cheap USB sound card for audio frequencies. I was very naive about FFT devices when I bought the Tek instrument. It is a nice instrument but not for an audio spectrum analyzer. For a PC (probably a laptop) and a $50 USB sound card, you can see from 5 Hz to at least 20 KHz all in one sweep on the screen of your PC. Once you deal with it for a while you wonder how you ever got along without it. Now, with that said - THD error starts creeping in above about 5 KHz but there is a lot to see between DC and 5 KHz especially PS and 60 Hz noise. I hope you try it out. Just download either ARTA or SpectraPLUS-SC software and use the sound card already in your PC. You will have to attenuate the signal off your dummy load to about -30 dBm to keep from over-driving and possibly damaging your PC input so be careful there.

[@ElPasoTubeAmps]

Greetings from El Paso and a friend... I just got a Tektronix TDS 784A scope and was searching around for information about it and the FFT function. All too often I run into my own videos. Holy Cow... sometimes it is as hard to learn from the Internet and KZbin as it was in the 1960's from books in the library. Anyway, how are you? I hope all is well. We have weathered our two weeks of winter and now spring and the winds are on their way. Life goes on. David

[@gudipatimaheswari6855]

How to check thd??

[@ElPasoTubeAmps]

I don't think we can get a direct THD reading from this scope but you can see the relative amplitudes of the fundamental and harmonics and made some judgement of harmonic content as related to harmonic distortion. In a push-pull amplifier, the second harmonic distortion should be 40-60 dB below the fundamental with a third harmonic slight higher and a descending harmonics beyond the third.

[@billzadel3335]

How can I contact chip sx ? Thank you, Bill

[@ElPasoTubeAmps]

www.ebay.com/itm/Tektronix-THDP0200-200-MHz-High-Voltage-Differential-Probe-Ships-From-The-USA/153223682364?hash=item23acd7d93c:g:wYAAAOSwtuVa7jJe:rk:12:pf:0 Above and below is a listing from Chipxs. They are also listed as BNC Surplus Electronics but they are Tektronix out of Oregon. www.ebay.com/sch/chipxs/m.html?ssPageName=STRK%3AMEFSXS%3AMESOI&_trksid=p2053788.m1543.l2654

[@profimax_ru]

Hi. Thanks for the video. Is this oscilloscope comfortable for everyday usage with common measurement? What about delays and noise? I've got a possibility to buyTektronix TDS 1002 for $200. Do you think it is reasonable at 2019? Or CRT preferred?

[@ElPasoTubeAmps]

It is a nice scope and it seems to me that $200 is very reasonable if it is in nice shape. I don't use mine that often as I have too many other oscilloscopes and stick to my 2467 and TDS 784A scope for most of my measurements. I think I bought this scope primarily for the FFT function to use on audio and it does not good a good job for that purpose. A much better option for FFT audio is a simple USB audio device (I use a single channel Focusrite unit) and a software package like SpectraPlus or ARTA. I don't have a definite preference for a CRT scope but sometimes an analog scope is still nice to have just like a vintage VOM.

[@profimax_ru]

Thank you for the answer. It would be nice to see a video review of all your oscilloscopes and measurement devices.

[@abdullahalazki7867]

مال التقنية يشوفوا الفيديو 😅