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Re: Next steps for the TinySA #spectrum_analyzer

 

Gary,

Do you have experience with an auto attenuator setting?
I could imagine doing a full range sweep with widest resolution bandwidth and set the attenuator to keep the strongest signal below say -20dBm.
This would take 300MHz (given max 250MHz low pass filter)? / 600kHz (max RBW) = 500 points to sweep.
A small button next to the Attenuator setting would fit.
W.r.t the spurs. Most will disappear after shielding is applied. In particular to the attenuator, the low pass filter and the first mixer.
--
HBTE Files section:?/g/HBTE/files
Erik, PD0EK
Re: Next steps for the TinySA #spectrum_analyzer

 

Erik,
I am just looking to make a usable 1-100MHz9or so) SA for my HF homebrew and boatanchor mod projects.
I don't care to go up to GHz at all..
Now that you have a programmable attenuator, how about an "auto set" attenuator?
Anything else that you can do to reduce or analyze spurs would be good.
Thanks again for all the excellent work so far!
73,
Gary
WB6OGD
Next steps for the TinySA #spectrum_analyzer

 

Now the TinySA is fully functional I could not help thinking about next steps.

Dynamic range (IIP3, noise level), RBW filters are ok.
Going to harmonic mode above 868MHz is no fun and using below signal LO between 434 and 868 is also difficult due to the mirrors.Just in case you want to re-use as much as possible but want to extend the frequency range you have the following options

1: Increase the IF to reach 900MHz
Instead of the LO SI4432 module a ADF4350 from eBay could be used, these start at 16$. Do NOT buy a cheap black ADF4350 module as these have considerable more spurs. For best performance you will need a amplification module as the ADF4350 outputs max +5dBm and that is insufficient drive te get the best performance of the first mixer. Using a different low pass filter and a rather small bandwidth home build? 900MHz cavity IF filter you get a zero till 900MHz spectrum analyzer with the same performance.?

2: Use? a cheap extra high IF stage to reach 2GHz
As the first ADE25-MH mixer is good till a bit above 2GHz you could consider adding two ADF4350 modules, an extra mixer and a cavity filter somewhere between 2 and 2.6GHz with bandwidth of 100MHz or less. This will give you a 2GHz spectrum analyzer where you reuse basically everything from the TinySA except the LO SI4432 module. The extra cost is two ADF4350 modules for 15$ each, an additional ADE25-MH module and a home build 2GHz cavity filter (simpler to build as there are less bandwidth requirements) for about 20$

3: Ignore cost and go up to 3GHz
Another options is to use two MAX2870 modules, 2 mixers capable for 3-6GHz and a 3GHz cavity filter. This will be substantially more expensive as the MAX2970 modules go for above 50$ each

The SA.exe SW is prepared for all these options as the configuration of IF's and LO's is completely flexible. You can even go for a I/Q mixer and FFT based last IF or subharmonic mixers.
You only will need to adapt the arduino SW to control the new modules but there are complete examples for controlling a ADF4350/ADF4351 available

Let me know how you see the future of your TinySA
--
HBTE Files section:?/g/HBTE/files
Erik, PD0EK
Re: Completing the TinySA with an input attanuator #spectrum_analyzer

 

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THANK YOU Erik, it just keeps getting better and better!
I was going to ask you about the PE4302 boards.. you beat me to it.
I am still waiting for parts...
73,
Gary
WB6OGD


On 12/18/2019 8:30 AM, erik@... wrote:

For some measurements an input attenuator is essential. Adding a step attenuator is pure convenience as manually adding input attenuation works also.
I went for a ready made module found on eBay that uses the affordable 3.3Volt compatible PE4302 step attenuator.
There are two versions, one using parallel (6 parallel bits) input and the other with serial (e.g. a data and clock line) input to control the 64 attenuation steps from 0dB till -31.5dB
There where sufficient free bits on the arduino zero so I choose parallel as can be seen in this picture of all modules together. The step attenuator is at the middle bottom, before the low pass filter.



The SA.exe controls the step attenuator through the P5 message.
I will update the arduino code in the files area to incorporate this added functionality

The only thing left to finish the TinySA is to add shielding to the modules and put it in nice box. .

--
HBTE Files section:?/g/HBTE/files
Erik, PD0EK

Re: Completing the TinySA with an input attanuator #spectrum_analyzer

 

¿ªÔÆÌåÓý

THANK YOU Erik, it just keeps getting better and better!
I was going to ask you about the PE4302 boards.. you beat me to it.
I am still waiting for parts...
73,
Gary
WB6OGD


On 12/18/2019 8:30 AM, erik@... wrote:

For some measurements an input attenuator is essential. Adding a step attenuator is pure convenience as manually adding input attenuation works also.
I went for a ready made module found on eBay that uses the affordable 3.3Volt compatible PE4302 step attenuator.
There are two versions, one using parallel (6 parallel bits) input and the other with serial (e.g. a data and clock line) input to control the 64 attenuation steps from 0dB till -31.5dB
There where sufficient free bits on the arduino zero so I choose parallel as can be seen in this picture of all modules together. The step attenuator is at the middle bottom, before the low pass filter.



The SA.exe controls the step attenuator through the P5 message.
I will update the arduino code in the files area to incorporate this added functionality

The only thing left to finish the TinySA is to add shielding to the modules and put it in nice box. .

--
HBTE Files section:?/g/HBTE/files
Erik, PD0EK

Completing the TinySA with an input attanuator #spectrum_analyzer

 

For some measurements an input attenuator is essential. Adding a step attenuator is pure convenience as manually adding input attenuation works also.
I went for a ready made module found on eBay that uses the affordable 3.3Volt compatible PE4302 step attenuator.
There are two versions, one using parallel (6 parallel bits) input and the other with serial (e.g. a data and clock line) input to control the 64 attenuation steps from 0dB till -31.5dB
There where sufficient free bits on the arduino zero so I choose parallel as can be seen in this picture of all modules together. The step attenuator is at the middle bottom, before the low pass filter.



The SA.exe controls the step attenuator through the P5 message.
I will update the arduino code in the files area to incorporate this added functionality

The only thing left to finish the TinySA is to add shielding to the modules and put it in nice box. .

--
HBTE Files section:?/g/HBTE/files
Erik, PD0EK
Re: Adding a input low-pass filter to the TinySA #spectrum_analyzer

 

And here are the measurements.
First 128MHz from a SI5351 through a -30dB attenuator


The fractional spurs around 128MHz are visible but the signals at 27.66MHz and 155.66MHz should not be there.
Lets see what happens when you add the 250MHz low pass filter



This is already much better. The signals at 27.66MHz and 155.66MHz where clearly aliases as they are now gone.
The advantage of a low-pass filters is it does not increase measurement time.
But if you have a lot of time you can add spur reduction with averaging. Lets see what that does:



This look as is expected.
--
HBTE Files section:?/g/HBTE/files
Erik, PD0EK
Adding a input low-pass filter to the TinySA #spectrum_analyzer

 

Using the excellent filter calculation tool that can be found here:

I calculated a 9th order?Chebyshev low pass filter?


As you can see the tool can be told to use standard E12 components.
The calculated values fitted nicely in an assortment of SMD L and C components I bought some time ago.
With these low values it would be best to put the filter on a PCB but I did not want to make one so I re-used a bias-T module I had from some previous experiment.
The result is a nice small filter?

.Next step is to see if this indeed eliminates the aliases seen when measuring the ADF4351 signal generator

--

HBTE Files section:?/g/HBTE/files

Erik, PD0EK

250MHz_filter.jpg

Re: Building and tuning a narrow band 2GHz cavity filter

 

On Fri, Dec 13, 2019 at 01:36 PM, Joerg ex-DB2OO wrote:
SPF5189z
I checked the datasheet. For the amplification of the LO signal 12dB should be ok. Just reduce the adf4351 output a bit. For the amplifier after the first mixer you have to add loss from first mixer (-7 dB?) and the cavity (-5 dB?) with 12dB and make sure your second mixer can handle that. My cavity has a bit more loss so I am ok with spf5189z.
It's easy to test by inserting a 10dB attenuator after the cavity filter. If that improves the IIP3 you have too much amplification.

--
HBTE Files section:?/g/HBTE/files
Erik, PD0EK
Re: Building and tuning a narrow band 2GHz cavity filter

 

The one I got is claimed to be 20dB but at 2GHz is only 9dB
Look carefully at the datasheet
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HBTE Files section:?/g/HBTE/files
Erik, PD0EK
Re: Building and tuning a narrow band 2GHz cavity filter

 

What did you use for the 9/10dB amplifiers? I have not found any LNAs with such a low gain on eBay. It is easy to find LNAs with >20dB, e.g. SPF5189z, but none with just 10dB. One could build those oneself with e.g. the ERA-2SM and a 6dB audit attenuator, but the ones on your picture look commercially built?
Re: Instructions for TinySA updated in files areas

 

SA.exe always have been a 32 bit executable so you only need the 32 bit runtime. So I had to remove the reference to 64bit runtime. No need for me to change the build

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HBTE Files section:?/g/HBTE/files
Erik, PD0EK
Re: Instructions for TinySA updated in files areas

 


Hi Erik,
???? I am a bit puzzled by that "doing a 32 bit build", (but it could be just my ignorance of anything 64 bit).
I am using Windoze XP+SP3 and your software runs without any problem, at least in the demo mode. So to me that implies that your software must already be 32 bit.
??? Sorry if that seems like an stupid comment to the "must upgrade" brigade. If it does then please forgive me.
By the way - I do really like your updated instruction .pdf. Well done.
Tony (G3PTD).
Re: Instructions for TinySA updated in files areas

 

Indeed, I am doing a 32 bit build, will update the instructions accordingly.
--
HBTE Files section:?/g/HBTE/files
Erik, PD0EK
Re: Instructions for TinySA updated in files areas

 

SUCCESS.
Thanks Erik, I have managed to get your SA to come up on my HP Windows10 laptop.

Final problem was to install the Microsoft Visual C++ 2010 SP1 Redistributable Package (x86,
even though I am running 64bit.? And re-boot one more time? ;-)

Now its time to buy some hardware I guess.
Thanks again for all your knowledge and help, looks like I can learn a lot from this project!
73,
Gary
WB6OGD
Instructions for TinySA updated in files areas

 

I updated the build and usage instructions for the TinySA
There is some extra info added on how to use the SA.exe control program.
--
HBTE Files section:?/g/HBTE/files
Erik, PD0EK
Re: How good, or bad, is the tinySA?

 

¿ªÔÆÌåÓý

Hi Erik,

?

I still get a warning from Norton who erases the file. I have to repair the quarantine.

?

The good news is that the SA.EXE starts up now.? I get a few error messages but I have to play a little bit more to understand.

?

Thanks and I will keep you informed.

?

73 de on7uf? Roland

?

?

?

Van: [email protected] [mailto:[email protected]] Namens Roland Rutsaert
Verzonden: dinsdag 10 december 2019 12:07
Aan: [email protected]
Onderwerp: Re: [HBTE] How good, or bad, is the tinySA?

?

Thank you Erik,

?

I will report

?

73 de ON7UF? Roland

?

Van: [email protected] [mailto:[email protected]] Namens erik@...
Verzonden: dinsdag 10 december 2019 9:53
Aan: [email protected]
Onderwerp: Re: [HBTE] How good, or bad, is the tinySA?

?

I uploaded a new SA.zip file containing additional error checking and reporting.
Can you try?
--
HBTE Files section:?/g/HBTE/files
Erik, PD0EK

Re: How good, or bad, is the tinySA?

 

¿ªÔÆÌåÓý

Thank you Erik,

?

I will report

?

73 de ON7UF? Roland

?

Van: [email protected] [mailto:[email protected]] Namens erik@...
Verzonden: dinsdag 10 december 2019 9:53
Aan: [email protected]
Onderwerp: Re: [HBTE] How good, or bad, is the tinySA?

?

I uploaded a new SA.zip file containing additional error checking and reporting.
Can you try?
--
HBTE Files section:?/g/HBTE/files
Erik, PD0EK

Re: How good, or bad, is the tinySA?

 

I uploaded a new SA.zip file containing additional error checking and reporting.
Can you try?
--
HBTE Files section:?/g/HBTE/files
Erik, PD0EK
Re: Two Questions about the Mini SA

 


Thank you for the reply Niels.
?? I had already ordered filter elements from Australia when I saw it, but it was fascinating to follow the link that you provided. There often some fantastic prices for components on Ebay, and right next to the sensibly priced identical parts. I wonder if they ever catch anybody.
Tony (G3PTD)
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