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M6DBL
05-17-2012, 07:05 AM
Hi All,
I wonder can some body give me some guidance regarding buying a new osilloscope. I have a perfectly good and fully working old fashioned analogue oscilloscope. However it's not really up to amateur radio work, the main reason being that it's bandwidth is limited to about 25Mhz. Looking on the internet I can see many modern digital osilloscopes that have a bandwidth of between 100 and 200 MHz, and are very competitivly . These are a far different item to the sort of oscilloscope I have been used to, so I have some questions that I hope you good people can help me with.
One of the things I notice on modern oscilloscopes is that they can perform certain math functions. I am quite used the old fashioned scopes where you can add or subtract one vertical channel from another. However almost all these modern digital scopes have the ability to do FFT (Fast Fourier Transforms). This is area I most want help with. My question is, that while I realise the ability to do FFT's does not make it the same as a proper spectrum analyser, but it does allow you to display frequency on the X axis against amplitude on the Y axis. So, would a modern DSO that can perfom FFT's be suitable for looking at the output of an HF transceiver to check for unwanted harmonics and spurious. Any help or advice would be much appreciated.
73
Dave
M6DBL

WN6U
05-17-2012, 02:25 PM
From the TDS1002 Manual:
- Analyze harmonics in power lines.
- Measure harmonic content and distortion in systems.
- Characterize noise in DC power supplies.
- Test impulse response of filters and systems.
- Analyze vibration.

Here is a link for you to consider
http://www.tek.com/learning/oscilloscope-tutorial

Agilent probably has similar information.

KD0CAC
05-17-2012, 03:34 PM
I was in the same position and heard about Rigol , and check with one of my favorite tech checkout sites - Dave's EEVBlog , an electrical engineer that does Checkouts and tear downs on YouTube , I would give some links but on the road using my phone , that I am not smarter than , yet :)

KA9JLM
05-17-2012, 05:17 PM
You may want to consider a spectrum analyzer.

Many times a 25Mhz O-Scope will go much higher, if you know the deterioration curve it can be used at much higher frequency.

A spectrum analyzer may be a better choice, If you really want to get serious.

VK6ZGO
05-18-2012, 01:29 PM
I was in the same position and heard about Rigol , and check with one of my favorite tech checkout sites - Dave's EEVBlog , an electrical engineer that does Checkouts and tear downs on YouTube , I would give some links but on the road using my phone , that I am not smarter than , yet :)

I would second that,Dave's EEVBlog is an excellent resource.
One thing you have to be wary of,is that some Digital Oscilloscopes reduce their sample rate,& hence their bandwidth when used at long time/div settings.
Others still, mainly cheap,handheld, units lie in their specs!
The FFT function is a very poor imitation of a Spectrum Analyser.
Don't be too quick to write off Analog 'scopes,as you can buy very capable older units for around half the price of a Rigol.
That said,if you really are sold on a Digital unit,the Rigol has a very good reputation among the people on the EEVBlog Forum.
It is also useful to look at w2aew's videos on the same site.

73,VK6ZGO

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