[ASK] Precautions needed for a noob with a spectrum analyzer

[BravoV]

Recently by luck, scored an used bench type 9KHz - 3GHz spectrum analyzer, and as noob regarding this fine piece of T&M equipment, I have read few precautions needed (more to read), and think I need to hear experienced members here regarding your wise advice.

This is my SA's input :

Click to enlarge.

So please excuse few 1st noob questions  :

- Is it important to always use the so called "DC Block" adapter on the input to reduce the risk of typical noob's mistake ? Or any other comments on this.

- Aware there are so many "cheap Aliexpress" type sales on this DC block, are they "decent" for this SA ? Yes, I'm currently lurking & stalking a 1st tier branded used DC Block online. Or any other suggestion ?

- What is the RF Surge Protection ? As locally I got an offer of one of this, can I use this "temporarily" to secure the SA instead of a real DC Block adapter as this needs time to score a good one yet relatively cheap, and no, I can't afford a new one. 


- Or any other suggestions or advice for a noob, please.

Thanks in advance for your help.

[tautech]

You'll need the official datasheet to be sure how much the input can handle.

The SSA3000X models are rated similarly: Maximum input DC voltage +/- 50 VDC

VDC isn't all you need be concerned about, more so max dB and that can be managed with internal attenuation (again check datasheet for how much is available) or external attenuation. 20dB is a pretty normal value to have on hand and it's the default (not max) internal attenuation for SSA3000X models.

[BravoV]

You'll need the official datasheet to be sure how much the input can handle.

The SSA3000X models are rated similarly: Maximum input DC voltage +/- 50 VDC

VDC isn't all you need be concerned about, more so max dB and that can be managed with internal attenuation (again check datasheet for how much is available) or external attenuation. 20dB is a pretty normal value to have on hand and it's the default internal attenuation for SSA3000X models.

My SA official datasheet -> NS-30 Spec (PDF)

[tautech]

You'll need the official datasheet to be sure how much the input can handle.

The SSA3000X models are rated similarly: Maximum input DC voltage +/- 50 VDC

VDC isn't all you need be concerned about, more so max dB and that can be managed with internal attenuation (again check datasheet for how much is available) or external attenuation. 20dB is a pretty normal value to have on hand and it's the default internal attenuation for SSA3000X models.

My SA official datasheet -> NS-30 Spec (PDF)

The important stuff is there:

RF Input Maximum Input level ±50VDC +30dBm

Attenuator Range 0 to 50dB, Selected manually or automatically coupled to reference level
 Resolution 10dB steps

Now you just need to learn how to drive it !
Dive over to the SSA3000X thread and look at the excellent usage examples by rf-loop.
https://www.eevblog.com/forum/testgear/siglent-ssa3000x-spectrum-analyzers/

[tautech]

BravoV
Further to just point out the modern approach is have an integral DC block which your unit by virtue of a 50V input rating will have.
When I got my SA I had similar fears to you of damaging the input but with some little knowledge gained from members here and very careful initial small steps you will gain confidence as to what you can do with it.
Achieving useful results on the display with just a near field loop is a safe way to make progress and become familiar with the UI before advancing to actual connection to a DUT.
Play it super safe and conservative to start with and you'll be fine.

[PA0PBZ]

That arrestor is NOT a DC block, it is a lightning arrestor and will happily conduct DC because most GPS antennas do have a preamp built in.
What you need is a DC block which is simply said a capacitor, the trick is to get a capacitor that is big enough to not attenuate the lower range of the SA (9 KHz).
So check the specs of any DC block you are going to get and see if the lower range is acceptable for what you are going to feed the SA with.

[tggzzz]

What you need is a DC block which is simply said a capacitor, the trick is to get a capacitor that is big enough to not attenuate the lower range of the SA (9 KHz).

And linear enough that high voltages don't change its capacitance, thus changing the low frequency cutoff and/or creating harmonics.

So check the specs of any DC block you are going to get and see if the lower range is acceptable for what you are going to feed the SA with.

Yes.

Don't try to make your own. For RF (as opposed to audio) look at Minicircuits.

[Shock]

Gotta measure em all! Went through a similar process when I got mine though I'm mainly interested in ULF to LF. I think it is common sense, similar to a scope you need to have an idea up front of the characteristics offset/amplitude of the signal you are measuring before connecting the front end, try not to use the instrument as an exploratory tool and use attenuation if necessary. You also have ratings on adapters and termination and need to be mindful to "err on the side of caution".

These links have some tidbits, but it would be nice to see some deep dives on the subject. I'm always interested in how not to destroy gear. A nice project would be to make a few RF pads and a diode detector circuit.

http://literature.cdn.keysight.com/litweb/pdf/5989-8791EN.pdf
https://www.criticalcomms.com.au/content/test-measure/article/protecting-test-equipment-from-rf-damage-1405796639#axzz59jBWCOaY
https://cdn.rohde-schwarz.com/pws/dl_downloads/dl_application/application_notes/1ma201_1/1MA201_9e_spectrum_analyzers_meas.pdf

[mnementh]

So what is the "probe power" for? A FET high-impedance probe, or an active attenuator probe of some sort?


mnem
Every day you learn something is not a wasted day.

[Shock]

So what is the "probe power" for? A FET high-impedance probe, or an active attenuator probe of some sort?

It's a power source for compatible high impedance probes.

[BravoV]

BravoV
Further to just point out the modern approach is have an integral DC block which your unit by virtue of a 50V input rating will have.
When I got my SA I had similar fears to you of damaging the input but with some little knowledge gained from members here and very careful initial small steps you will gain confidence as to what you can do with it.
Achieving useful results on the display with just a near field loop is a safe way to make progress and become familiar with the UI before advancing to actual connection to a DUT.
Play it super safe and conservative to start with and you'll be fine.

Thank you, I thought I was too paranoid, as current the SA input N connector is the 1st and the only one in the house, and currently I just powered it on as don't have anything and the ball to connect anything into it yet.

What is "near field loop" are you talking about ? Mind elaborate further ?

[BravoV]

That arrestor is NOT a DC block, it is a lightning arrestor and will happily conduct DC because most GPS antennas do have a preamp built in.

Thanks, noted. As I suspected. 

What you need is a DC block which is simply said a capacitor, the trick is to get a capacitor that is big enough to not attenuate the lower range of the SA (9 KHz).
So check the specs of any DC block you are going to get and see if the lower range is acceptable for what you are going to feed the SA with.

Now, finding the "right" DC block that is good enough for my SA input range and also cheap, that is the hard part. 

[BravoV]

What you need is a DC block which is simply said a capacitor, the trick is to get a capacitor that is big enough to not attenuate the lower range of the SA (9 KHz).

And linear enough that high voltages don't change its capacitance, thus changing the low frequency cutoff and/or creating harmonics.

So check the specs of any DC block you are going to get and see if the lower range is acceptable for what you are going to feed the SA with.

Yes.

Don't try to make your own. For RF (as opposed to audio) look at Minicircuits.

Noted, especially the DIY one, definitely its not in my plan. 

[BravoV]

Gotta measure em all! Went through a similar process when I got mine though I'm mainly interested in ULF to LF. I think it is common sense, similar to a scope you need to have an idea up front of the characteristics offset/amplitude of the signal you are measuring before connecting the front end, try not to use the instrument as an exploratory tool and use attenuation if necessary. You also have ratings on adapters and termination and need to be mindful to "err on the side of caution".

These links have some tidbits, but it would be nice to see some deep dives on the subject. I'm always interested in how not to destroy gear. A nice project would be to make a few RF pads and a diode detector circuit.

Shock, thank for the links and docs. Yes, I've watched the Alan's one hence the DC Block hunt.

Curious, what kind of SA you have that does ULF to LF ?

[BravoV]

So what is the "probe power" for? A FET high-impedance probe, or an active attenuator probe of some sort?

It's a power source for compatible high impedance probes.

Yep, and still don't have any idea what kind of connector is that ? 

Attached below the close up shot and it's outputs rating.

[BravoV]

Reading one of the Keysight document above, on the highlighted text, what is that ?

Sort of a shorting cap for the N connector ? 

[tautech]

BravoV
Further to just point out the modern approach is have an integral DC block which your unit by virtue of a 50V input rating will have.
When I got my SA I had similar fears to you of damaging the input but with some little knowledge gained from members here and very careful initial small steps you will gain confidence as to what you can do with it.
Achieving useful results on the display with just a near field loop is a safe way to make progress and become familiar with the UI before advancing to actual connection to a DUT.
Play it super safe and conservative to start with and you'll be fine.

Thank you, I thought I was too paranoid, as current the SA input N connector is the 1st and the only one in the house, and currently I just powered it on as don't have anything and the ball to connect anything into it yet.

What is "near field loop" are you talking about ? Mind elaborate further ?

You've a few options so I'll just give you some links in which to get a handle on them and then decide whether to buy something or DIY.
https://www.eevblog.com/forum/projects/diy-magentic-field-probes/
https://www.eevblog.com/forum/testgear/new-affordable-emc-probe-set-at-a-bargain-price-from-ariel-rocholl's-lab/
https://www.edn.com/design/test-and-measurement/4380475/Near-field-probes-sniff-circuits

Obviously if you need accuracy characterized probes are the way to go but I'd suggest you DIY from a loop of coax.
That will at least get you started and give you a 'feel' for how to use a SA.
You can use these on scopes too but you don't have the BW like a SA has.

[Shock]

Curious, what kind of SA you have that does ULF to LF ?

HP 3580a 5Hz-50kHz and I also have a HP 3581c selective voltmeter. 

Shown here but my HP 3580a has the balanced input (takes both balanced and non balanced sources) and battery option.

[tautech]

Let me just say I'm no wiz with a SA, just that I've had to come up to speed some due to wanting/needing to sell them.
Read as much as you can, not just the links I've added and try to get a handle on those here that 'know their stuff'.
I've mentioned one already and there's several more following whose opinions I deeply respect.
Look here:
https://www.eevblog.com/forum/testgear/kirkby-calibration-kit-alternatives/

It can be a deep rabbit hole but it is fun. 

[tautech]

Reading one of the Keysight document above, on the highlighted text, what is that ?

Sort of a shorting cap for the N connector ? 

Not all SA's are created equal....sensitivity, input robustness etc.

Check if the KS has:

Further to just point out the modern approach is have an integral DC block which your unit by virtue of a 50V input rating will have.

[BravoV]

You've a few options so I'll just give you some links in which to get a handle on them and then decide whether to buy something or DIY.
https://www.eevblog.com/forum/projects/diy-magentic-field-probes/
https://www.eevblog.com/forum/testgear/new-affordable-emc-probe-set-at-a-bargain-price-from-ariel-rocholl's-lab/
https://www.edn.com/design/test-and-measurement/4380475/Near-field-probes-sniff-circuits

Great links,  thanks again Rob. 

I guess I will be busy reading and gathering more infos especially on the DIY field probe 1st.

Obviously if you need accuracy characterized probes are the way to go but I'd suggest you DIY from a loop of coax.
That will at least get you started and give you a 'feel' for how to use a SA.
You can use these on scopes too but you don't have the BW like a SA has.

Accuracy on RF part is not my priority now, as this purchase is never planned, I didn't even expect to own a SA.
It really changed a lot in my learning direction.

My highest scope bandwidth is only at 400 MHz analog, this 3 GHz thingy is really quite a big jump in my T&M inventory.

[BravoV]

Curious, what kind of SA you have that does ULF to LF ?

HP 3580a 5Hz-50kHz and I also have a HP 3581c selective voltmeter. 

Shown here but my HP 3580a has the balanced input (takes both balanced and non balanced sources) and battery option.

Cool piece of equipment  , ULF & LF .. no wonder with battery option for low noise stuff.

[BravoV]

Let me just say I'm no wiz with a SA, just that I've had to come up to speed some due to wanting/needing to sell them.
Read as much as you can, not just the links I've added and try to get a handle on those here that 'know their stuff'.
I've mentioned one already and there's several more following whose opinions I deeply respect.
Look here:
https://www.eevblog.com/forum/testgear/kirkby-calibration-kit-alternatives/

Yes, I'm aware of few fellas here looking the way they share/post their knowledge, that I believe are RF kung-fu masters. 

It can be a deep rabbit hole but it is fun. 

Damn, I'm now just walking thru the hole's gate ...

[vk6zgo]

Reading one of the Keysight document above, on the highlighted text, what is that ?

Sort of a shorting cap for the N connector ? 

Basically a load of bollocks ! ( as far as ESD is concerned)
We used to carry spectrum analysers all over the state without caps on the connectors.

If you havep them, though, by all means use them, as they protect the thread on the outside of the "N" connector.( BNCs are worse, even though they don't have threads, they are much more prone to da
The problem is that, unless they are captive to the instruments

[BravoV]

Related to BNCs , other question, attached below the rear ports, I do know common types like serial, VGA, printer port, GPIB too, and the 10 Mhz reference clock BNC, its capable of as input or output.

How about these BNCs ? Do I need a special extra precautions on these ? I am not saying like hooking up to mains voltage  , but are they also ultra sensitive sort of like the main input ?

Mechanically wise, I know how to protect BNC as I have lots of those silicone caps for BNC.