Hi all
I’m looking for suggestions for spectrum analyzer that has the following
- high Z input ( but i guess i can get active probe)
- only need up to 11 or 12 Mhz
- tracking generator in box or support for external one is a must.
- 1 measured channel , 2 channels nice to have but not required
- vintage unit to keep my budget low unless modern USB units can do this
- Must measure THD, markers and 3db points
- would need to store one scan and compare with a second like A/B Or display both simultaneously for visual matching and measuring
- export via gpib to print or save or maybe some software out there (usb if modern unit)
- support to display on a larger external screen would be nice like vga out for example or other means
This is for hobby work not a business so can’t cost too much <500 hopefully that’s possible.
Myself i only know hp 3585a that meets the need and still over my budget so looking for others.
Thanks
Paba
I’m looking for suggestions for spectrum analyzer that has the following
- high Z input ( but i guess i can get active probe)
- only need up to 11 or 12 Mhz
- tracking generator in box or support for external one is a must.
- 1 measured channel , 2 channels nice to have but not required
- vintage unit to keep my budget low unless modern USB units can do this
- Must measure THD, markers and 3db points
- would need to store one scan and compare with a second like A/B Or display both simultaneously for visual matching and measuring
- export via gpib to print or save or maybe some software out there (usb if modern unit)
- support to display on a larger external screen would be nice like vga out for example or other means
This is for hobby work not a business so can’t cost too much <500 hopefully that’s possible.
Myself i only know hp 3585a that meets the need and still over my budget so looking for others.
Thanks
Paba
it all depends on the dynamic range you need. With a limited dynamic range you can get there with a Picoscope. I had an older ADC 200 that could do all of that. I still have 2 I don't use. That generation used a bidirectional parallel port but worked remarkably well. There is a Picoscope 3204A on eBay for $300 that can do a decent spectrum analysis. probably other digital USB scopes as well. My Siglent can do it but the display is not too useful.
I would caution against older spectrum analyzers since they tend to be big heavy and delicate.
I have 2 Tek 7L5's which are excellent but you need a mainframe etc. which can get out of hand fast.
If what you want is a network analyzer that's different and more challenging. There is this: NanoVNA | Very tiny handheld Vector Network Analyzer Those are cheap, with limitations.
I would caution against older spectrum analyzers since they tend to be big heavy and delicate.
I have 2 Tek 7L5's which are excellent but you need a mainframe etc. which can get out of hand fast.
If what you want is a network analyzer that's different and more challenging. There is this: NanoVNA | Very tiny handheld Vector Network Analyzer Those are cheap, with limitations.
Depending on the dynamic range you need (there that is again...), a Digilent Analog Discovery 2 might do the job for you. Well within your price goal.
Ok thanks
I checked into that and more is always better especially to be better than the DUT but I would say 70db would be fine, more is better but certainly 90bd+ would be overkill.
BTW I just came across the HP 8590L still reading the data sheet to see and not sure what the going price on these is but also looks promising. I'll look at that Discovery unit as well of course.
/Paba
I checked into that and more is always better especially to be better than the DUT but I would say 70db would be fine, more is better but certainly 90bd+ would be overkill.
BTW I just came across the HP 8590L still reading the data sheet to see and not sure what the going price on these is but also looks promising. I'll look at that Discovery unit as well of course.
/Paba
Out of interest, how low does the 7L5 go in terms of sensitivity? What's the lowest signal it can work usefully with? I don't need one as I have modern FFT analysers, but I have a few working 7000 MFs and have long fancied the 7L5. I've always thought it would be eye candy for the lab, that's not massively useful. But you use it regularly? I could possibly stick it on the O/P of our 2722 which gets used rarely on account of its lack of live FFT.
Thanks
On screen is 80 dB I think. I don't remember the max sensitivity off hand. I have used it occasionally. Its great for looking at ultrasonic residue from DAC's since it goes to 5 MHz with a 5 Hz bandwidth. I also used it with some other stuff to calibrate an FM modulator and Modulation analyzer. I would just use a soundcard FFT or I used to use a Picoscope on the output of an AP system 1 which worked great. You don't need a lot of dynamic range. You no need a narrow bandwidth to separate real stuff from noise.
Hi Paba,
don't forget that when measuring THD, you can extend the useful dynamic range of a spectrum analyser by using a notch-filter to filter out the fundamental frequency by a known amount.
I seem to remember a dedicated thread discussing this.
Also, using a 'Distortion Magnifier' as designed by Bob Cordell can achieve an extension of dynamic range.
Cheers
Mike
don't forget that when measuring THD, you can extend the useful dynamic range of a spectrum analyser by using a notch-filter to filter out the fundamental frequency by a known amount.
I seem to remember a dedicated thread discussing this.
Also, using a 'Distortion Magnifier' as designed by Bob Cordell can achieve an extension of dynamic range.
Cheers
Mike
Great point.
I’m seeing distortion measurements of -150 dBc with a notch filter approach and a QA401. So, I bet you could get well better than -100 dBc with a passive Bridge-T notch filter, one of Victor’s test generators, and an Analog Discovery 2.
Analog Discovery 2 THD Measurement
I’m seeing distortion measurements of -150 dBc with a notch filter approach and a QA401. So, I bet you could get well better than -100 dBc with a passive Bridge-T notch filter, one of Victor’s test generators, and an Analog Discovery 2.
Analog Discovery 2 THD Measurement
How low does it need to go? Few spectrum analyzers go below 9 kHz. Dynamic signal analyzers (DSAs) do, but not all of them go much above 100 kHz.
The Analog Discovery is a ridiculous deal for what it is. Seriously, a 14 bit ADC with 10 MHz bandwidth for something like $250. Bandwidth is a bit limited, and you won't get 10 MHz out of it, however.
The Analog Discovery is a ridiculous deal for what it is. Seriously, a 14 bit ADC with 10 MHz bandwidth for something like $250. Bandwidth is a bit limited, and you won't get 10 MHz out of it, however.
As much as I wanted a nice heavy HP, ordered on of these.
tinySA | Main / HomePage
Seems despite what the specs say it goes down to 20 kHz and should have no trouble covering the 10.7 MHz I need. A few very encouraging videos on youtube as well.
Lets see in a few weeks when this finally arrives.
tinySA | Main / HomePage
Seems despite what the specs say it goes down to 20 kHz and should have no trouble covering the 10.7 MHz I need. A few very encouraging videos on youtube as well.
Lets see in a few weeks when this finally arrives.
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I'm really interested. I could unload et sell some of the big boxes and get some space back.
Your mention of 10.7 MHz suggests you are looking at FM IF performance. It will be interesting to find out how well this works for those tasks.
Your mention of 10.7 MHz suggests you are looking at FM IF performance. It will be interesting to find out how well this works for those tasks.
Hi Damian,
yes the need for SA is to minimize odd harmonics and maximize even harmonics while dialing in least distortion measured in parallel.
Also another good thing to do is adjust the pilot cancelling or post MPX filters to lower the 19 kHz that might still leave the unit. But the TinySA may not go that low. You could send me a PM if you have anything to let go but I know some of these units with TG are still going for reasonable money. Like I said anything could cover 20Hz to 11-12 Mhz with TG and hi-Z input would be the ideal boat anchor for me.
yes the need for SA is to minimize odd harmonics and maximize even harmonics while dialing in least distortion measured in parallel.
Also another good thing to do is adjust the pilot cancelling or post MPX filters to lower the 19 kHz that might still leave the unit. But the TinySA may not go that low. You could send me a PM if you have anything to let go but I know some of these units with TG are still going for reasonable money. Like I said anything could cover 20Hz to 11-12 Mhz with TG and hi-Z input would be the ideal boat anchor for me.