How to use a Rigol DS815-TG

[w3amd]

I have the following questions regarding this because I don't want to blow up the front end. I have vast software experience and I'm expanding into hardware. I know a lot about oscilloscope measurements and how to use them and it will be my first time using this device this coming Monday.

1) Tracking generator output is 50 ohms. Input is 50 ohms. Can I hook a coax cable directly from the TG output to the Spectrum Input?

I think this answer is yes.

2) Is there a way to test a single pole filter? Let's say for example there is 10K in series and some capacitance to ground (0.01 uF). Can you put this circuit in line with the tracking generator output and Spectrum input?

I think this answer is yes if I set the output and input of the tracking generator and spectrum input to uV or mV.

3) Can I hook up a dipole antenna for about 4 meters directly on the input of the spectrum input but use this to look for low frequencies (~10-100 kHz)?

I think this answer is also yes but be careful of any very close signals which may be in this band?

TIA
John

[georges80]

yes,yes,yes.

GOOD purchases for you is to get a 10db and 20db inline pair of attenuators (bnc male/female on the ends) to insert inline when you first try new things at the RF input of your dsa - ESPECIALLY an antenna etc.

cheers,
george.

[w3amd]

Thanks George!

Cheers. I'll look into the additionally attenuators.

John

[Z80]

Hi John,  I have this SA as do a lot of people it seems and it is very good for the price. 
Regarding your questions:
1) Yes, using 50 ohm coax of course.  This is how you zero the trace before taking a 'through' measurement of your device under test.  You may want to buy or make 2 leads so you can join them together with an adapter to do the zero, then remove the through adapter and plug in your device to measure it.  The built in TG isn't powerful enough to damage the front end, so passive devices are safe to measure.  You need to take care with active devices like amplifiers / oscillators etc.

2) Yes, one of the intended uses for the TG - combo.  Just remember that you are testing in a 50 ohm setup, the response may not be the same if your circuit isn't also 50 ohms.  Regarding the units, it is common to use the default dbm when measuring as you are effectively just plotting loss vs frequency.

3) Yes you can, 4m of wire isn't a problem although it won't pick up much at that low frequency?  A dipole for 100khz will be 1500m long.  Be careful with larger outdoor antennas as they can hold a static charge which can damage the front end.

[xrunner]

3) Can I hook up a dipole antenna for about 4 meters directly on the input of the spectrum input but use this to look for low frequencies (~10-100 kHz)?

As the others have said yes, yes, yes. Plus you can use a long wire antenna to pick up WWV on 10 or 15 MHz to check the calibration. 


I have a question about a small bug I found. I posted it in another DSA815 thread but if anyone read it they didn't respond. If you do a screen shot to a USB stick, using the .jpg format, it stores it "upside-down". If you use either .bmp or .png, it stores it "right-side up". Yes I realize I can fix it with a graphics editor, but I was wondering if anyone else can duplicate it. I have firmware 01.15.01.

Thanks.

[w3amd]

XRunner I can check your question when I get into the office tomorrow and start the testing (if this is my highest priority). Things tend to change rapidly.

John

[w3amd]

Hi John,  I have this SA as do a lot of people it seems and it is very good for the price. 
Regarding your questions:
1) Yes, using 50 ohm coax of course.  This is how you zero the trace before taking a 'through' measurement of your device under test.  You may want to buy or make 2 leads so you can join them together with an adapter to do the zero, then remove the through adapter and plug in your device to measure it.  The built in TG isn't powerful enough to damage the front end, so passive devices are safe to measure.  You need to take care with active devices like amplifiers / oscillators etc.

2) Yes, one of the intended uses for the TG - combo.  Just remember that you are testing in a 50 ohm setup, the response may not be the same if your circuit isn't also 50 ohms.  Regarding the units, it is common to use the default dbm when measuring as you are effectively just plotting loss vs frequency.

3) Yes you can, 4m of wire isn't a problem although it won't pick up much at that low frequency?  A dipole for 100khz will be 1500m long.  Be careful with larger outdoor antennas as they can hold a static charge which can damage the front end.

Yes, I went thought Dave's video on the normalization.

Yes, I have some amplifiers I might test but I will load them to 50 ohms on purpose. I would just be looking at the frequency response range. I understand is using dbm I am using a power scale therefore the meter is expecting 50 ohms and if I deviate from that I need to proportion it. I expect that if I use a scale like uV or mV this would not matter.

I would just be looking for any radiated frequency, particularly the clock frequency of my offending inverter.

Thanks,
John