Author Topic: DSA815-TG: TG in LF Applications  (Read 903 times)

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Offline Nachtaktiver

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DSA815-TG: TG in LF Applications
« on: April 05, 2016, 12:24:13 AM »
Hello Guys,
before I started this topic I already used the search function but I couldn't find a direct answer to my question. So I give it a try.

For my workbench I intend to buy a DSA815-TG spectrum analyzer. Beside of being a normal spectrum analyser with the internal tracking generator it could be used as a (el cheapo) low cost
scalar network analyzer. I clearly know that the intended usage of such a device is limited to HF applications but has anybody of you used it in LF applications? On top of that I found several
datasheets were the TG frequency range specification is decribed with "9 kHz up to 1.5 GHz" or "100 kHz up to 1.5 GHz" which is quite confusing.

So I have several question and I hope you can help me out:
a) Was there a hardware revesion where they have the TG frequency range specification?
b) Has anybody used the TG as a scalar network analyzer in LF application? Like measuring the frequency response of a LF circuit.  (For example a 10kHz low pass filter)
c) What are your opinions of the TG in LF applications overall?

I know that the DSA815-TG is a low cost device and the dynamic, accuracy or other parameters are quite limited. But I could imagine that it's still good enough for me and my workbench and private usage. Maybe some of you guys could post some pictures of the frequency reponses (LF) so that we all can evalute the qualities of the internal TG. I'm sure that some of you here in the forum are interested in
this and it could be a help for others who plan to buy a DSA815-TG.

Nachtaktiver
 

Offline Earendil

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  • Country: hu
Re: DSA815-TG: TG in LF Applications
« Reply #1 on: April 05, 2016, 06:33:18 AM »
First of all I don't have the Rigol 815. But I'm pretty sure it works down to it's specified frequency whatever that is.
The question is why do you want to use such a low frequency and are you sure that you really need a SA?

If you don't need the high dynamic range than you can use an oscilloscope + FFT.

If you do need the high dynamic range than are you sure that you want 50 ohm input impedance? Do you have an active probe for example?

Are you really sure that you want to use this as a low frequency RF network analyzer for 50 ohm characteristic impedance signals? Because that's a pretty uncommon application.

If you need high impedance inputs and the high dynamic range then consider dynamic signal analyzers or audio analyzers.
You can find them on Ebay easily. You might even consider something like this: https://www.quantasylum.com/content/Products/QA400.aspx
 

Offline Nachtaktiver

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  • Country: de
Re: DSA815-TG: TG in LF Applications
« Reply #2 on: April 05, 2016, 08:12:02 PM »
Hello Earendil,
maybe my first post wasn't so clear as I though, but to make it clear I don't want to use the SA for LF applications only and I will use it for a lot of stuff. I was just
brainstorming and started to think about the usability of a SA for other tasks.

I don't own an active probe but as soon as I own a SA I will design my own active probe adapter and other usefull stuff in the near future. I'm also planning to design an LISN for low voltage DC circuits and will get into the measuring of cable intererence and EMC pre compliance tests.


I was just curious what I could also do with a SA and started to ask here about the LF thing.

Thank you for your kind answer.
 


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