Author Topic: Spectrum analyzer  (Read 850 times)

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Offline tatersalad

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Spectrum analyzer
« on: November 04, 2020, 05:47:26 am »
 Long story short im getting deeper into ham radio and I enjoy the thought of building my own amps and low pass filters. So I took the plunge and bought a ssa3021x. It arrived today and I started to tinker with it (my first SA) and for the life of me I cant get it to display anything. Im using a wire in the input side as an antenna and a little 433 mhz remote as my transmitter. No physical contact just near field. Ive tried manual settings and the auto set button and I see nothing but noise on the display. Is it me or could I have possibly gotten a bum unit? Any tips or tricks for a noob?
 

Offline Brumby

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Re: Spectrum analyzer
« Reply #1 on: November 04, 2020, 05:54:30 am »
Screen shot?
 
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Online tautech

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Re: Spectrum analyzer
« Reply #2 on: November 04, 2020, 06:03:31 am »
Set the span to from 400-450 MHz. Amplitude settings may also need adjusting for greater sensitivity and possible the Preamp needs be ON.
Take care about overloading the input and if you hear the warning beep or see the display warning make adjustments  so the input is not overloaded.

While you learn near field is best rather than a direct connection that could damage the input.
Get a DC block, attenuators and adapters and some SMA cabling as it's cheap and good to work with.
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Offline Brumby

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Re: Spectrum analyzer
« Reply #3 on: November 04, 2020, 06:08:05 am »
(I was hoping he'd show up  :) )
 
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Online tautech

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Re: Spectrum analyzer
« Reply #4 on: November 04, 2020, 08:51:56 am »
Now with a bit more time to hunt out a 2yr old post and screenshot.

339 MHz Aussie Merlin garage door remote sniffed near field with a coax RF loop. Showing adjustment back onto correct frequency that restored a good 20m+ range.



Only 10 MHz span and narrowing it further will show some of the communication taking place.
You can do much with just a simple RF loop and being contactless it's great to learn use of a SA without the risk of frying it.
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Offline Mouse69

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Re: Spectrum analyzer
« Reply #5 on: November 04, 2020, 09:03:00 am »
For a probe, take a look at Dave's video



or search for eevblog near field probe in youtube (safer than random links)

I hope your SA fine.  Fingers crossed.
Cut towards your chum, not towards your thumb
 
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Offline tatersalad

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Re: Spectrum analyzer
« Reply #6 on: November 04, 2020, 11:06:26 am »
Thanks ill get back at it in 10 hours, this work thing keeps taking up all my play time ill update you guys here in a bit. Thanks for all the help so far I never heard a beep or saw a warning. The box was a little beat up and it didn't have a screen protector on it when it showed up so im wondering if it was a returned unit.
 

Offline Mouse69

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Re: Spectrum analyzer
« Reply #7 on: November 04, 2020, 11:21:44 am »
Did you get the tracking generator option?

If you did, you could connect the left connector via a cable to the right connector.

With the TG off, you should just see the noise floor (say down at -120db).   Turn the TG on, I think it defaults to -20db, so you should see 9KHz to 2.1GHz trace at the -20db (a line from left to right much higher up than the noise floor).

You can also vary the TG output level.  It should be a flattish line, there is also a correction setting to flatten it (so you can then put a unit in the cable path, e.g. start with two cables and a connector, set the TG correction, replace connector with unit to test.)
Cut towards your chum, not towards your thumb
 
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Offline Mouse69

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Re: Spectrum analyzer
« Reply #8 on: November 04, 2020, 11:30:48 am »
If you don't have the TG option, you could try and use it as a very expensive radio (see if you get commercial radio signals 80MHz - 108Mhz - here in the UK)



You tube again, searching for 'ssa3021x plus'  There are some really good demo videos to get you started that you could try to see if your unit works as expected.
Cut towards your chum, not towards your thumb
 
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Offline tatersalad

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Re: Spectrum analyzer
« Reply #9 on: November 04, 2020, 01:54:34 pm »
Yes I did get the tracking generator, is it safe to connect the two ports directly without an attenuator? I have leads coming today, if so I can test that today. I have a 70cm hand held I could use but wasn't sure if 5 watts non contact would overload the front end or not. Im scared of blowing this thing up if you can't tell lol. Any recommendations on dc blocks and attenuators?
 

Offline Mouse69

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Re: Spectrum analyzer
« Reply #10 on: November 04, 2020, 04:44:19 pm »
You can use the TG on the SSA in this way (connecting the ports) - another video found...



BUT if you were connecting an amplifier for instance, you may want a load/attenuator and/or a DC block to protect the input.  Due to the signal being to powerful or containing a DC element.
Cut towards your chum, not towards your thumb
 
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Online Mechatrommer

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Re: Spectrum analyzer
« Reply #11 on: November 04, 2020, 05:34:47 pm »
Yes I did get the tracking generator, is it safe to connect the two ports directly without an attenuator?
from the datasheet. SSA3021X input is quite robust with ±50Vdc and 33dBm (±14Vac) capable. i guess it has its own DC block so it should be safe to connect directly to the built in TG-SSA3000X TG/FG (0dBm max).
It's extremely difficult to start life.. one features of nature.. physical laws are mathematical theory of great beauty... You may wonder Why? our knowledge shows that nature is so constructed. We simply have to accept it. One could describe the situation by saying that... (Paul Dirac)
 
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Online tautech

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Re: Spectrum analyzer
« Reply #12 on: November 04, 2020, 05:49:05 pm »
Did you get the tracking generator option?
FYI all Siglent SSA's and SVA's come with TG enabled as standard fare for free. Once it was an option however for some years now it has been free.
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Offline tatersalad

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Re: Spectrum analyzer
« Reply #13 on: November 04, 2020, 08:30:41 pm »
Ok so it looks like it sees the TG, if I unplug the jumper coax it moves the display so I guess that means this might all be operator error? I did the 1.3.9.6 sw update first thing out of the box just a fyi
 

Online tautech

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Re: Spectrum analyzer
« Reply #14 on: November 04, 2020, 09:06:54 pm »
Ok so it looks like it sees the TG, if I unplug the jumper coax it moves the display so I guess that means this might all be operator error? I did the 1.3.9.6 sw update first thing out of the box just a fyi
To get a feel for how SA's operate spend some time in these 3 menus:
Frequency
Amplitude
TG

Just play with the TG for now adjusting its amplitude and within the Amplitude menu: Ref position, Scaling /div (sensitivity) and Preamp.

Once you have any near field probe or the like on the input even your phone in your pocket handshaking with your WiFi or a cell tower can set off the input overload warnings when looking at higher sensitivity. For this reason I park mine on the other side of the room when working on antennas or with near field probes.
Don't be too daunted getting to know these as they're pretty hard to break....but you can if negligently careless.
Have fun.  :)
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Offline tatersalad

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Re: Spectrum analyzer
« Reply #15 on: November 05, 2020, 03:09:18 am »
well after a little sleep and some testing... it as all operator error. im sorry guys it was 1am and i thought for sure i killed it some how. does anone have a link to a trusted attenuator by chance? looking to check the harmonics on a 100 watt solid state amp eventually and want to make sure my back side is covered. thanks again for all thel help ill sleep better tonight
 


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