Siglent SSA3000X and SSA3000X-Plus Spectrum Analyzers

[benishor]

And while we're at it, I was considering adding some protection diodes on the input when changing the switch. Does anyone have an idea on what the part the footprints are there for?

[DL4JY]

And while we're at it, I was considering adding some protection diodes on the input when changing the switch. Does anyone have an idea on what the part the footprints are there for?

Hi, I believe adding protection inside the SA is not the best way doing it - even Siglent does not use them.

Why not adding an external protection ?

I have made myself a few "engineering boards" which are just having a 50 Ohm stripline , SMA connectors and GND. With something like this you can experiment with different diodes, TVS whatever, and see instantly the result.  Once you found a design suiting your needs, you can either put this in a small tin box or manage to get these elements e.g. into two N- or BNC -Connectors male/female without any coax cable. I have done that many years ago to build attenuators, Diode detectors etc. Performs quite well up to 3 GHz.

I hope you are able to get your SA working again.

best regards,

Juergen

[oz2cpu]

>Sorry to hear that oz2cpu, I feel your pain.

Thanks a lot mate.. yes i was actually so mad, and sad, it took me 2hrs to fall a sleep yesterday,
mostly on my self, for beeing so mega stupid.. i knew this SSA input was a weak spot, i knew how to protect against it,
and i knew how to minimize the risks, yet did i ignore and forget all good known tricks..
now it is 11 and i just got up..

>Any idea on how it happened?

YES i know EXACTLY what happened, in fact i got a VIDEO of me blowing up the front end !!
since i was making another one of my test and teardown videos for youtube :-( 
maybe it is a good idea to cut out that sad and stupid part out..
i was thinking about filling the unit i was testing with gunpowder put in in a large field, and shoot target at it..

so what did i do :
the unit i was testing did not use correct mains socket with earth pin
= missing earth to its chassis, i even see this !! yet continue to power it on (first mega stupid)
The front panel got a BNC RF output connector, i connect this to my SSA3021X
and forget to put my normally always connected 10dB attenuator on the SSA (2nd mega stupid)

The BNC connector turns out to be a home-brew plug in, into the old larger hole with a 4mm banana in the end,
this BNC adapter is made of plastic, so there is NO gnd connection at all !!
(i could not have known this, it was invisible from the front when not pulled out)

I even got painfull electric shock when touching the test units chassis, due to leakage / capacity to mains ! (3rd mega stupid for continue)
and at that point i pull out the BNC adapter and realize it is homebrew made of plastics,
i do complain about low RF level, in fact it looks like -30 to -40 of what i should expect.
when i pull out the bnc-banana adapter, and in again, i see no more RF signal on SSA, (4th mega stupid for in again)
(NOW i realize how brain dead i was... jaw dropped on the floor for beeing so clue less and stupid)
it starts with head in the hands for 2 mins, trying to remember all the bad words i am not alowed to say

and yes.. all of this is in a video clip.. dont even dare to watch it.. it is how bad i feel..

so if any of this can save one of your SSA
it was worth sharing.

please remember : the more clever and smart you think you are..
the higher risk to forget even the most simple things,
always : go slow.. do all things right, you know how, you know what to do.

[oz2cpu]

here is part 1 of my SSA3021X front end repair video

https://youtu.be/geoafvnSW3Q

[Johnny B Good]

>Sorry to hear that oz2cpu, I feel your pain.

Thanks a lot mate.. yes i was actually so mad, and sad, it took me 2hrs to fall a sleep yesterday,
mostly on my self, for beeing so mega stupid.. i knew this SSA input was a weak spot, i knew how to protect against it,
and i knew how to minimize the risks, yet did i ignore and forget all good known tricks..
now it is 11 and i just got up..

>Any idea on how it happened?

YES i know EXACTLY what happened, in fact i got a VIDEO of me blowing up the front end !!

======snipped interesting tale of woe=============

please remember : the more clever and smart you think you are..
the higher risk to forget even the most simple things,
always : go slow.. do all things right, you know how, you know what to do.

 I know exactly what you mean as per my own inexcusable act of stupidity as told in this post:-

https://www.eevblog.com/forum/projects/ublox-neo-m8n-gps-navigation-signal-amplify-module-for-arduino-rasppery-pi/msg2426871/#msg2426871

 In hindsight, the financial loss was but a pittance not just compared to your experience but in the grander scheme of my "Cheap GPSDO Project" although when I was trying to DIY a GPSDO for cheaper than those overpriced (imho) ready made units, it didn't seem so at the time.

 Of course, some three years on, after investing the best part of a £100 in three M8T modules (£41 for the first and two 'spares' priced at just £24 each three weeks later from the same seller) followed by another £200 investment in an Efratom LPRO-101 just to compare my GPSDO's output against a stable enough reference free of GPS disciplining phase wobbles, the cost of that mistake has now taken on a new perspective in that I can console myself that it had been a relatively cheap 'learning experience'.

 Hopefully, you can get your SA repaired for a not too sizeable fraction of its original cost.

[benishor]

here is part 1 of my SSA3021X front end repair video

https://youtu.be/geoafvnSW3Q

Thank you, Thomas! That is a very nice video showing the details of opening up the beast which is clearly helpful for me and for others too. Can't wait for the second part of the video which will hopefully end up with the fixed analyzer!

Good luck es 73 de yo6ssw!

[oz2cpu]

thanks a lot for the messages and posts on the video..
I see in this, and many other threads on EEVBLOG, I am far from the first, and maybe not the last..
I feel better if some learn from this, and we see much less fried front end posts in the future,
so spread the word to you Spectrum Analyzer friends, who allready know how fragile the input it..
tell them once again, it is nost an old story.. it is really true..

[hendorog]

One silver lining is that these modern instruments are highly repairable - with parts we can actually get hold of.

Looking forward to the repair details, appreciate you making the videos as you are helping all of us here   

[oz2cpu]

here is the video.. where i blow the SSA3021X RF front end.

https://youtu.be/gcHxyg9XWFo

[oz2cpu]

>I found a nice easter egg while looking at the firmware. If you open the Mode menu and type 7445368 on the numeric keypad

Dont work on normal SSA software ??
i just tried, nothing..

[tautech]

>I found a nice easter egg while looking at the firmware. If you open the Mode menu and type 7445368 on the numeric keypad

Dont work on normal SSA software ??
i just tried, nothing..

X or X Plus ?
We know it works with SVA models so it should also work with X Plus models.....same HW. 

[oz2cpu]

>X or X Plus ?

SSA3021X no plus written on the front here
and no easter egg,
if I click MODE and start typing, it thinks i want to dB something

[tautech]

>X or X Plus ?

SSA3021X no plus written on the front here
and no easter egg,
if I click MODE and start typing, it thinks i want to dB something

Only SVA and SSA X Plus models it seems carry eggs:
https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg4241503/#msg4241503

[oz2cpu]

here is part 2 of the video

https://youtu.be/zQ1lPbTwKaU

[RoV]

here is part 2 of the video
https://youtu.be/zQ1lPbTwKaU

Thank you for the video, but... don't you think the unit would need recalibration after dismounting, changing the switch and remounting? I wouldn't bet it is still inside specifications.
Is the calibration procedure available somewhere? If the 3021X is similar to the X+, calibration data is written in a bunch of binary files contained in a folder named "SA-firmdata0/cali". I imagine they are produced by an automated procedure during manufacturing, but there must be a means of updating them after a repair.

[oz2cpu]

i dont use it for any kinds of certification measurements, so a db more or less, here or there, i care not..

but check the specs of the switch i changed, it is very small dB it can vary in its insertion loss

the alu shields and pcb, are made so it will be very close to same location, so.. i am happy as it is.
The alternative is to take it back to work, and compare its measurements to another one, with a brand new call sheet,
I got access to that in a few month, so of course i try that.

[tautech]

i dont use it for any kinds of certification measurements, so a db more or less, here or there, i care not..

but check the specs of the switch i changed, it is very small dB it can vary in its insertion loss

the alu shields and pcb, are made so it will be very close to same location, so.. i am happy as it is.
The alternative is to take it back to work, and compare its measurements to another one, with a brand new call sheet,
I got access to that in a few month, so of course i try that.

The PV tests start on P14 of the service manual:
https://int.siglent.com/u_file/document/SSA3000X_ServiceManual_E01B.pdf

[tv84]

Does anyone already have experience with cross-flashing a factory fresh SSA3021X+ which has newest FW V3.2.2.5.0?

Try this method.

You need to get the previous SVA FW but, if it works, then you can flash the newest SVA FW version.

[benishor]

I finally managed to find the time to change the front-end switch on my SA as well. @oz2cpu, thank you for your videos, they helped with dismantling the beast. I took some pictures along the process here: https://photos.app.goo.gl/Y8G1irPk9EzuXMM5A

It looks like my hardware revision is a bit different from oz2cpu's, namely the way the rf board and shielding is. I don't know which is newer.

As for the result, I like the flatness of the TG but I seem to have some amplitude discrepances compared to my other HP 70000C SA. I am using a HP 8656B signal generator with both and I get -1.8dB reading @ 990MHz on the Siglent compared to the HP. The difference reduces with frequency. I do not remember if the difference was there to begin with but I would assume not.

One problem during the fixing process is that after I hot aired the new switch, I took down the capton tape and used the soldering iron to touch the switch pins; during the process a bit of solder fell on the switch output microstrip (half of it, as you can see from the pictures). I used solder wick to try and remove it as best I could. I am not sure if this makes a difference or not.

Another thing I can think of is that the unit needs to be recalibrated but I don't know how to do that. I inspected the menus but did not find such a thing. I would expect to be able to plug in a correction curve or something like that.

Can anyone please help with this?

P.S: very impressed with the build quality of the unit. It's a beautiful piece of engineering from Siglent!

[benishor]

I also made these measurements, perhaps they provide more insight: https://docs.google.com/spreadsheets/d/18hqW8TiC1fAGkZ6ko35K19osOYpmgXjIjTDdKNzEp_w/edit?usp=sharing

[DL4JY]

a bit of solder fell on the switch output microstrip

as most of the RF-current is flowing on the copper line in the dielectric medium - on the underside of the micro-stripline - the effect of a bit of tin on the upper side  should not be that large.

as reference : https://incompliancemag.com/article/pcb-return-current-distribution-in-a-microstrip-line/ 


cheerio

Juergen

[benishor]

a bit of solder fell on the switch output microstrip

as most of the RF-current is flowing on the copper line in the dielectric medium - on the underside of the micro-stripline - the effect of a bit of tin on the upper side  should not be that large.

as reference : https://incompliancemag.com/article/pcb-return-current-distribution-in-a-microstrip-line/ 


cheerio

Juergen

Thank you very much, Juergen! That is good to know!

[Bad_Driver]

Thanks for your very good photos of your repair process, it will help others!

You have the SSA3000X+ which is newer than the SSA3000X of OZ2CPU.

[RoV]

Thank you very much for the detailed photos, although I hope I won't need them  .
I am surprised of the discrepancy between the tracking generator readout, where the -20 dB seem very accurate at low frequency, and the results of the other check. You should also check with a power meter. Also, I would suggest checking with different values of input attenuation, to make sure no other switch/attenuator is compromised.
Regarding the switch you replaced: if I'm not wrong, it is used for S11 readout in SVA mode (it routes the reflected wave coming from the tracking port into the SA input), so it can be tested only in SVA mode.
One further doubt: I assume you cleaned the flux residues on the chip before closing. In the last photographs they are still present.

[Bad_Driver]

I also made these measurements, perhaps they provide more insight: https://docs.google.com/spreadsheets/d/18hqW8TiC1fAGkZ6ko35K19osOYpmgXjIjTDdKNzEp_w/edit?usp=sharing

Today I checked my SSA/SVA against my RF generator. The RF gen goes "only" up to 1 GHz. Yesterday it was to hot in my lab under the roof (29 deg, now 24)

Attached the diagram with values.
For -20 dB and -10 dB there was no Preamp and no attenuator on the SSA used, for 0 dB the attenuator was set to "auto". Cable is a self made RG316 with SMA connectors.
The result is much better than the limits of the RF gen. (TGR1040, +/- 2 dB). I do not assume that the SSA and the RFG "compensate" their errors 
If someone has a better RF gen or a Power meter other results will be appreciated!

I think your repaired SSA is doing well!