I designed spectrum analyzers for Hewlett Packard as my first job out of collage in 1971. The group I worked in is now called Keysight. They were very expensive but I see you can buy one now for a few hundred dollars and get a spectrum analyzer that works to 22GHz. Wow. I worked on the log amplifier that had a dynamic range of 100dB. Loved this video. I think that this cheap analyzer is mixing the input down to DC but the filter is actually a bandpass with a bandwidth of about 250 KHz and a center frequency of about 200 KHz. Thus when you input a signal you see both the + and - image products of the mixer output spaced 400 KHz apart. The display occupies that plus the bandwidth of the filter so they call it 1 MHz. When the LO is tuned to the frequency of the input signal the output is DC and the filter blocks it so you see what looks like a notch in the output.
Yeah that's very plausible. Thank you! That both side bands are visible seemed obvious. But how is this avoided in the design of professional instrumentation?
@@LutzSchafer It gets very complicated as there are way more things to worry about than just the issue with this cheap spectrum analyzer. But for the question asked I will give a short reply. If you want to analyze .1 to 2.5 GHz, mix the input up to 3.6 GHz. Then the LO goes from 3.7 to 6.1GHz and the difference signal is 3.6 and the sum is 3.8 to 8.6 and can easily be filtered out. Then use another mixer to get the signal down to 300 MHz and another to get to 21MHz where I built the Log amp. These frequencies need to be carefully selected so that harmonics of the LO do not put spurious signals in band so they are picked more carefully that what I did in the above example. Hope this helps.
Let's wait for Andreas' answer ... (but) If you go back you'll find re. "🤠" that he is/used to be a steampunk afficionado... (zurich maker faire 2017) 73 de 🚲
Best "organized" Vid in TH-cam! Please never give up your style of "summarization". -seems yet another piece of equipment where I have to know the result before I can measure it... let me check the improvements ;)
@@AndreasSpiess - Yes, definitely on of the best organized tec chanel's over YT. And there are no wrong miss leading or confusing procedures. It's Swiss prescision content!!!
Let me say thank you for this video Andreas. I had this same device from banggood sitting on my desk and couldn't get it to work, i will be going back to it now that i have a better understanding of it..thank again.
Thank you for wonderful explanation! I got exact image of this spectrum analyzer (LTDZ_35-4400M). I had interest in notch characteristics for CW (Continuous Wave) that 145.55MHz in your video. I checked the circuit diagram and I understood the mechanism of that. Following 2 things are the points of the notch: - The same idea of DCR (Direct Conversion Receiver) - The characteristics of RBW (Resolution Band-Width) filter About the DCR, when we apply the same frequency signal for RF (measurement signal) and LO (Local Oscillator) of the mixer (IAM81008), the mixer output become DC signal. And amplitude of the DC signal depend on the phase difference between RF and LO. However, RBW filter has DC block capacitors, so DC voltage doesn't reach to Logamp (AD8307) input pin. These DC block capacitors are the major reason of the notch characteristics. About the RBW filter, I simulated RBW filter (including DC block capacitors) that using LTspice. It had f0= 200kHz +/- 100kHz of bandpass filter characteristics. When we apply CW to the RF input, Logamp input will appear twin peaks of signal because RBW filter has bandpass characteristics. I think your demonstration of 145.55MHz CW agree to my estimation. Because I seen the frequency difference between peak to peak is 400kHz (=200kHz*2) in your video. I got additional idea from these consideration. It is TG (Tracking Generator) offset frequency. In DCR idea, if LO and TG sweep with the same frequency, mixer output will be DC voltage. In this spectrum analyzer, we cannot see frequency spectrum because DC block capacitor blocks DC voltage. So in this spectrum analyzer, TG (become RF signal) and LO frequency should have offset value such as 200kHz.
Amazing explanation! I was trying to figure out what was causing the notch. This design was used to simplify the mixing stage, using just one, in contrast to "conventional", or "real" spectrum analyzers that uses two or more mixing stages, right?
I appreciates how you do the comparison in a very in-depth details. I works as a RF engineer and always find myself lacking in many area. This information is very useful to me on how normal practices are done based on different people and their background. Thanks man!
Perfect timing. I just ordered two BF-F8HP radios last week and started studying for my technician license. This week I learned about antennas, SWR meters, and the NanoVNA. So much new information introduced to me in such a short time I feel like I am in college again. Thanks for making this video to supplement what I am already trying to learn.
Thx for the walkthru, well done and I love how you link and make due diligence on these products and link to the relevant parts, that a possible owner can benefit from.(golden) many other channels can learn from the "viewer perspective-awareness" you seem to suit your videos with. well done Andreas. +1 Don't have this Spectrum analyzer but were looking into it as an entry tool to just get familiar with this kind of class apparatus. at around 30 bucks delivered for this unit (no shell), alternatives are not hanging on the threes in this sub 100 bucks environment.
If I understand everything correctly then this spectrum analyzer uses an low IF frequency of ~few hundred kHz, most spectrum analyzers use high IF that is higher than maximum frequency they can measure. Because of that it is going to see signals that are centered at LO +/- few hundred kHz and that's why there are 2 peaks when you measure signal of that handheld. That's very bad because some signals, like signal from that handheld will appear to occupy twice the bandwidth and have a weird notch in the middle as seen on the video.
I used my R&S FSEA20 analyzers almost every day for a seven year period. I got pretty used to these high performance machines that had a noise floor of about -160 dBM at zero span. Made my job easy. These days those analyzers can be had for about 1500 bucks in good working order.
You are right. I see a lot of people buying these old instruments. They are a very good choice if you have enough space and maybe also some knowledge to use/repair them. For you, as a long-time user, this is a perfect fit and not comparable with such a cheap device...
Thanks! I was looking at such a very device just the other day to analyse my antenna design. It's really cool that you showed another device @9m30s that is probably more what I was looking for. Thank you for your good quality videos.
Great videos :) Love the artificial hand...lol You have a great sense of humor along with great tech knowledge... Thanks for making it so much fun to watch.
You could say that the Mixer is a Multiplier. If you remember your trigonometry: sin(a)* sin(b) = (cos(a − b) − cos(a + b))/2 This is why the sum and difference of frequencies appear. In practice the Mixer is not perfect and there are nonlinearities that generates also harmonics so you get N*a + M*b (with N and M integers). But the other frequencies and usually much attenuated with a good Mixer.
@@AndreasSpiess I understand that just putting a trigonometry formula in a video can scare people 😆 I'm not a RF guy at all but I find that part of electronics quite stimulating. I just wanted to add some extra for the curious ones that asked themselves "how does a mixer work?"...
Excellent video, as usual, thanks very much, Andreas. That German "Tiefpaßfilter" should be at least 24 years old as it is written "Tiefpassfilter" since 1996. Now I know what a spelling reform is good for.
In my small lab I have an anti static workstation. Earthing, wrist strap points etc. Grounding for me, my equipment and soldering station. The sight of the purring cat is cute. Except all I could think of was "THE STATIC!".
Always looking forward to hearing from you! I’m not into RF much myself (except when having to filter harmonics, hee hee), but your videos are always didactically well prepared so it’s pure joy watching them and there’s always something to learn. And of course I dig cat-lovers, having had my own lab cat for ever so many years. :-) Anyways, thanks for being there, doing all this and even teaching an old fart new tricks from time to time!
wow this is so cool. I am starting to check out how to build a SDR radio telescope and one video used a cheap spectrum analyzer test the 21cm astronomy hydrogen line. This is a all new learning curve on making a homemade radio telescope using SDR software. 😎 thanks a lot.
You saved me $50. I might have bought this for fun. Also from the comments I learned that the Germans have abandoned the old version of "ss" which I learned back in the 1970-s. The "sharp s" which it was called here. (Where is it on my keybord?)
I think that the 'notch' is not RBW-related issue, but due to the LO 'step', since it appears that the design does not actually 'sweep', but uses discrete step sizes, or?
It's because when the frequency of the LO is exactly the same as the input frequency the output of the mixer is DC and the logarithmic amplifier does not amplify DC or very low frequency, also because of capacitor C29 which blocks any DC into the amplifier anyway. As the LO moves slightly above or below the input frequency then the frequency of the output from the mixer is again high enough to pass through C29 and for the AD8307 to amplify it. Apart from the notch this design has another flaw, that of 'reflections'. If for instance you were to look at an SSB signal it would appear as a double sideband one with suppressed carrier. In 'real' spectrum analysers they do not convert to DC but instead to an intermediate frequency of a few MHz and then measure the amplitude of that. That also eliminates the reflection problem.
@@listerdave1240 Thank you for explaining this phenomenon. This "notch" didn't make much sense given the theoretical principle of operation. BTW, isn't C18 also a problem?
@@listerdave1240 The AD8307 can handle up to 500MHz. An IF around 450MHz would stay well within the specs of the 8307 and make it easier to design the image rejection filter.
@@listerdave1240 This makes alot of sense. Why couldn't they just down convert to a constant IF like in any good old superheterodyne receiver? Then using a narrow band amp with filters would also filter out the odd integer multiples due to the square waveform of the LO. Yeah I realize this 50 bucks spend wasn't worth it's bang ...
Andreas, thank you for your outstanding work! Please, will you PLEASE update your Links at the bottom? Sadly a number of them no longer connect. Thank you again!
The solution of removing the display and just add an USB control makes instruments cheaper and, more importantly, smaller. I've made several USB instruments under the same principle. Actually, the video caught my attention because of this. Anyway, loved the video and also subscribed. Thanks for sharing!
I made a receiver with tracking ADF synth and nextion display some years ago. To have a flat power signal, I had to add an amplifier and a step attenuator (controlled by µC). It has to be calibrated ! Now I have +/- 1dB precision. (compared to my keysight at work)
Hi Andreas, some time ago I bought one of this chip device. I compared features wit a R&S in office lab: agree with your conclusion ... About SW, I tried to be in touch with the original designer but ( I can 100% understand why ) I did not receive an answer. Any way, googling and spent some time reading forum, I found Python driver and commands list ... ... but all is sleeping since "The job is not worth it"
Thanks for the video Andreas. My radio club bought a Rigol Spectrum analyser a few months ago and I wanted something similar for my little work bench and having found this on ebay thought it was a good little project ( I bought the naked board). I've only yesterday finished putting it into a case with N connectors and will be keen to try the new software. Love the cat on keyboard :-) Keep up the vid's, It's good to see a ham doing such a diverse range of topics.
Thank you for quality information. I'm using sdr + white noise Zener + spektrum software to align homemade vhf filters. Regarding my application my setup performs similar to NWT. At the end nothing can replace a good sigilent anritsu Hp spectrum analizer. Thanks again !!!
Good video. I had a look at this cheap device a few weeks back, my mouse cursor hovered over the 'buy now' button. After watching this review i decided NOT to buy it, save up more money for a proper one. This video saved me $55 and disapointement. Thank you Andreas !!
At 18:10 I think you made a mistake. Settings on Siglent are RBW 1MHz and att 20dB. This gives noise floor of instrument (as seen) around -45dBm. It can not measure beyond that and we see that smooth trace goes into noise. I assume that if you disconnected filter, noise floor will stay about -45dBm. Also at 8:20 you hit the noise floor of Siglent when measuring notch filter. Good LPF should have much greater out of band attenuation. Cheep analyser has noise floor at -70dBm as we can see. Please redo measurements with appropriate settings on Siglent. If I am wrong, please accept my apology. I don't own Siglent spectrum analyser to check by myself.
Thank you for this excellent review! I have a spare Agilent 6ghz directional coupler and plan to get this for a friend who needs to measure SWR for his home-built 3.5ghz 5G-antenna. It lacks speed and resolution as a spectrum analyzer, but I hope it works fine for plotting S11 curve.
I recently purchased a miniSA spectrum analyzer. I am Sure you’ve seen it. It is not all that different than the miniVNA. I would love to see you analysis of it and show too it’s usefulness and it’s weaknesses.
Excellent video as always! Two quick things... The link to the VNA video in the description is pointing to Amazon, not TH-cam. Did you do a video comparing the nanoVNA to the other VNA? I thought you had, but I can't find it.
I changed the link now. Thanks. And I did not do a comparison of the nanoVNA. There are quite a few videos out already and I still think, the N1201SA is the better deal for ISM band guys. I wait for the successor which will also cover more than 900 MHz with a decent resolution.
Thanks for the great video! After this video I bought this analyzer! I am a developer for electronic devices and I think this device helps me. Lg Szivatz.at from Austria
Thanks for the video! I found it really informative. I probably would have wanted one of these had I seen them for sale, but as I mostly would use it to measure harmonics from transceivers they are kinda useless. I think for cheap harmonics measurements an SDR dongle and attenuator is the way to go. I already have a Nano VNA for checking filters and antennas.
I would like to buy a spectrum analyzer for 2 reasons: 1-to familiarize myself with spectrum analyzers 2- find FM and LTE signals strenght for interference when I install antennas to be able to determine if FM or LTE traps should be used.Could the cheap one do the job?
Another very useful video thank-you. 2 years on I was hoping perhaps you had covered the Tiny SA spectrum analyser but could not find it on your page. I would be very interested to know how you find it.
@@AndreasSpiess Thanks for the reply. I have seen some videos. I was interested in how you personally found them. I think they are worth a try at the price.
Thank you Guy with a swiss accent. I visited Luzerne for 1 day. At night. It was okay. :) I want a spectrum analyzer. I don't have a use for it right off the top of my head but I would find a reason. Not swiss mentality but hey... this is internet.
Thanks Andreas a good informative video. I just purchased a unit off AliExpress not the same one you have here but its labled 35-4400MHz with a IN and OUT port and USB port. I hope it will work well for monitoring a wideband Digital DVB-S2/T ATV transmission at 1255 MHz...love your puscat I have a long hair pus too...Cheers Clint - VK3CSJ...
I am French. Can you confirm that the voice-over of this video is in English? I have a big doubt because I understood everything without problem! I have rarely seen a video of this quality on TH-cam, both technically and in terms of video editing and sound recording ... and with so much humor!
This is a very nice comment! Thank you. French nearly "killed" my career when I was young because of the bad grades. I only learned it when I worked in Cameroon... But since then I forgot most of it. Good that we can communicate in English.
This is not ham channel. It focusses on the ISM usage of RF because only a very few of my viewers are HAMs. Maybe I can motivate a few ISM guys go get licensed...
I do not know a lot of bode diagrams. But the device has a built-in tracking generator. Mind the minimal frequency if you would like to use it for audio.
Nice SA overview; i did think that you might add that one often uses a noise source, instead of a tracking generator, since it removes a couple of 'dependencies', but, that's a bit picky... i see that you mentioned the noise source right at the end! Sad, how often some inventive person's work becomes just one more source of a chinese company's income :-( When I was in Helsinki, i visited a showroom of "Finnish Design", showing off the truly-great breadth and quality of art, artisanship, and inventiveness of the people of this country of only 5.5 million people (a shameless plug for them! ), and, what do I see? A small group of mainland chinese (i recognised the mandarin language) , walking around, taking photographs of items... not just a 'snapshot', either, but pictures from every possible angle. Obviously, not just a 'tourist photo', they intended to go home, make a copy, and sell a few million. So, even when it's not 'visible', we may find the nice work of some German, Swiss, Canadian, Finn, at the heart of some chinese gear that is so inexpensive that we canpt avoid buying it...or, can we? Still, it would be a nice surprise for some German, or Swiss, ham person, to receive a few Euros/CHF in his bank or paypal, or 5€ in the post :-) !! itps just a thought....
I remember the 1980s where the Japanese did the same with our products. Nothing new. Switzerland still exists because we are very innovative. The same will happen again and again, I think. This is how the world moves. We were the leading country in textiles 100 years age... As you mention we can send these people a few Euros if we want. Like my patreons do it with this channel, for example.
Please do a video on SDRs and clever configurable (elegant design and possibly cheap using HEMTs/GaN) front ends. I was hoping for a bit more of a deep dive into that sort of thing when I was notified of this video.
@@AndreasSpiess $50? I'm confused as to the number you came up with as well as the significance-- I just would like to see an exploration of HEMTs before they're commonplace. Also, GaN transistors aren't very expensive now and they are underrepresented in enthusiasts' communities, so I thought you'd have an opportunity to deep dive where no man had before. It's ripe for clever approaches.
@@AndreasSpiess GaN transistors are cheap and extremely capable (maybe you were thinking of SiC?)-- for instance: www.digikey.com/products/en?WT.z_cid=sp_917_buynow&keywords=917-1153-1-ND
I thought your comment was about a device using this new technology ;-) I am no specialist in this and I also think it would be too special for this channel. Maybe others will cover it.
in summary: the price difference has its weight, then it depends on the use you want to make of it. $ 3,000 is a great investment for a hobby, so the $ 50 device might be enough, once you compare it to some more advanced device ( hoping you can do it) you have a "touchstone" for your purposes. If, on the other hand, you have to study the behavior of various equipment rigorously, perhaps for work, then you must think of a quality product such as Siglent or of equal quality. Tnx for yours intersting videos Andreas and i'll see you next time!
I most probably will not do a SA comparison on this channel. There are other channels focused on this topic. I just wanted to give some advice to people hoping they can save 2850$ to go to this cheap device ;-) And they should know a little on what they have to look if they buy another one.
@ Andreas Spiess: I completely agree with you: I was also a radio amateur, and I never had a spectrum analyzer .. in reality I was more of a CB than a real radio amateur (even if I had acquired a license and license: my name was Ik4DZF but some time has passed ... 20-25 years !!) and when I built the jpole for 144 MHz I went by attempts trying to respect the project's measurements ... it worked , at least to get on 144MHz repeaters :-)
About as expected for $50. But I would just go buy used SA off ebay. You can get some really incredible ones for very cheap. Devices which used to cost $150,000 can be purchased for only ~$500. Lesson learned: expensive high end lab test equipment doesn't retain any value and depreciates worse than even the worst automobile.
Would be nice to see you show this with an SDR, it eliminates some of the issues shown here (probably adds new different issues). You can use Spektrum made by Pavels on GitHub, I've helped on the development so if you have any question you can shoot me an email !
Very Interesting and useful. I was wondering if it would be possible to use one of these to perform Prequalification EMC / EMI RF tests in a DIY TEK cell. Or perhaps there might be some other way to get an idea before spending $$
Buyer beware. If you only need a *cheap* spectrum analyzer, get yourself a used RSP1 or RSP2 for about 100 € or even less and the spectrum analyzer software from sdrplay. Pretty accurate and much more sensitive than this crap here, although it is not as fast as a real spectrum analyzer. Andreas, well done this video!
Thanks Andreas. I'm interested in testing an area to find out what radio frequencies and signal strengths are present. What would be the most cost-effective way to approach this problem?
@@AndreasSpiess How much would you need to spend on either of these technologies in order to get something reliable and useful? Do you have any brands/models to recommend?
Very good info..I subscribed and plan to watch more vids. I have added some external filters and a 30db wide band LNA on the input of mine. It has made the spectrum analyzer more useable. It’s still not great, but much better. I also did clean up the Power supply and did the mods going around on the net. I added a variable attenuator on the in and TG out along with the ext Amps. I packed it a nice shielded cabinet its not as good as a real network analyzer, but it is actually useful now. I actually made a selectable multi filter selection for different band widths. The stock internal filtering was pretty bad. I may try to do some more improvements? We will see? Too many pokers in the fire. Great channel. I enjoyed watching.
Andreas Spiess . Thank you sir. I will try to put together all my info on the mods i made. Its pretty much chicken scratch now, but i will try to compile it i to something intelligible. I will be watching and i will let the channel know when i have good information to share. Thank you for the warm welcome.
Andreas I have done similar experiments with the same Banggood device. What struck me first was that the tracking generator produces more or less a square waveform. Presumably same is true for the LO since it uses the same chip. So the mixing products must contain odd harmonics of the LO. I also observed the dip when trying to display a single carrier tone. You have any idea what it's causing it? It almost looks like as if both side frequencies contribute to whatever is "measured". The symmetry kindof gives it away. BTW I like your cat :)
Viewer Allen Edwards below gives an explanation for the notch. Concerning square wave: You are right. But because the LO sweeps with the TG it (usually) does not see these harmonics. I mentioned that the Siglent has more filters. This is where some of them are. Its TG creates a sine...
I didn't quite understand where that false notch comes from. It is also quite prominent at the more detailed scan. Edit: Lister Dave's comment bellow explains it nicely. There is C29 capacitor that removes the very DC we want to measure. I Think that C18 may do the same. th-cam.com/video/PRsaGEk-EsQ/w-d-xo.html&lc=UgyDM9iflCNIOa0WzXV4AaABAg.95NRn9Qnwem95NTJCzMq0w
Unfortunatley you do not find old instruments in all countries. They are often sold in the US, and transport can become quite a problem for such heavy things :-(
I am sorry watching this video so late - have to be on a HAM-Fest at 9:30 here in Berlin today and bought 2 things to play with .... may be you should mention the cat-content at the end by your overview in the beginning - so viewers stay till the end.
I hope you liked the HAM fest! And maybe found a few interesting things. Concerning the cat: I think it should remain a "surprise" for the guys who stick to the end...
I nearly won a Tektronix 7613 for €20.00. I think it is obsolete but do you think is pointless to buy one of these according to the cheap spectrum analyzers you can get nowadays? I think this is very good for ELF from 1Hz onwards and I am interested in studying the brainwaves
I did not know it. But now I tried. Unfortunately I also was not successful. I tried to calibrate the SA and then measure the very same configuration. I would have expected to see 0 dBm across the spectrum. Unfortunately II did not see anything like that. :-(
I designed spectrum analyzers for Hewlett Packard as my first job out of collage in 1971. The group I worked in is now called Keysight. They were very expensive but I see you can buy one now for a few hundred dollars and get a spectrum analyzer that works to 22GHz. Wow. I worked on the log amplifier that had a dynamic range of 100dB.
Loved this video. I think that this cheap analyzer is mixing the input down to DC but the filter is actually a bandpass with a bandwidth of about 250 KHz and a center frequency of about 200 KHz. Thus when you input a signal you see both the + and - image products of the mixer output spaced 400 KHz apart. The display occupies that plus the bandwidth of the filter so they call it 1 MHz. When the LO is tuned to the frequency of the input signal the output is DC and the filter blocks it so you see what looks like a notch in the output.
This is when somebody understood the math behind the view... congrat!
Yeah that's very plausible. Thank you! That both side bands are visible seemed obvious. But how is this avoided in the design of professional instrumentation?
@@LutzSchafer It gets very complicated as there are way more things to worry about than just the issue with this cheap spectrum analyzer. But for the question asked I will give a short reply. If you want to analyze .1 to 2.5 GHz, mix the input up to 3.6 GHz. Then the LO goes from 3.7 to 6.1GHz and the difference signal is 3.6 and the sum is 3.8 to 8.6 and can easily be filtered out. Then use another mixer to get the signal down to 300 MHz and another to get to 21MHz where I built the Log amp. These frequencies need to be carefully selected so that harmonics of the LO do not put spurious signals in band so they are picked more carefully that what I did in the above example. Hope this helps.
By the way, the HP8566 weighed 100 pounds.
I suggest to watch the Signalpath video. There you see exactly what Allen explains: th-cam.com/video/Fn7uaEVeOPk/w-d-xo.html
My cat is a 1KHz detector, he came running, meowing every time you whistled. :D
Mine too! She doesn’t like this video :)
Thank you as my cat whined when he whistled and I did not know why but now do.
Sorry for that, guys!
@@AndreasSpiess It was kinda funny, he never comes running when I whistle, I must be off tune.
@Green Steve: My natural authority over small animals? ;-)
Wow. I understood how a Spectrum Analyzer is working and what it's for. In some 20 minutes. Thanks!
You are welcome!
@@AndreasSpiess BTW, Andreas (du ?), is the hat simply part of your personal style, or is it a kind of "Tracht"?
Let's wait for Andreas' answer ...
(but) If you go back you'll find re. "🤠" that he is/used to be a steampunk afficionado... (zurich maker faire 2017) 73 de 🚲
@@lohikarhu734 It's an 'ensemble' together with the 'lederhose'. Very common in alpine countries... ;-)
@@reinholdu9909 Steampunk :-)
Best "organized" Vid in TH-cam! Please never give up your style of "summarization". -seems yet another piece of equipment where I have to know the result before I can measure it... let me check the improvements ;)
Should improve the dynamic range...
Andreas tnx... btw:YOU (and QO-100 :) are driving me now to finally go for a HAM licence ...keep up the good work "in style" (=your's :)
@@AndreasSpiess - Yes, definitely on of the best organized tec chanel's over YT. And there are no wrong miss leading or confusing procedures. It's Swiss prescision content!!!
Awsome work and chanel. Thank you for your dedicated work. For this present moment the great tool is tinySA Ultra.
Lab cat. Very important. More valuable than the cheapie spectrum analayzer. Thank you for an informative video.
And also more expensive ;-)
and sometimes cats can be used as an ESD generator.... although usually when you weren't planning on it. :-)
Let me say thank you for this video Andreas. I had this same device from banggood sitting on my desk and couldn't get it to work, i will be going back to it now that i have a better understanding of it..thank again.
I hope it will work for you.
Thank you for wonderful explanation!
I got exact image of this spectrum analyzer (LTDZ_35-4400M).
I had interest in notch characteristics for CW (Continuous Wave) that 145.55MHz in your video.
I checked the circuit diagram and I understood the mechanism of that.
Following 2 things are the points of the notch:
- The same idea of DCR (Direct Conversion Receiver)
- The characteristics of RBW (Resolution Band-Width) filter
About the DCR, when we apply the same frequency signal for RF (measurement signal) and LO (Local Oscillator) of the mixer (IAM81008), the mixer output become DC signal. And amplitude of the DC signal depend on the phase difference between RF and LO.
However, RBW filter has DC block capacitors, so DC voltage doesn't reach to Logamp (AD8307) input pin.
These DC block capacitors are the major reason of the notch characteristics.
About the RBW filter, I simulated RBW filter (including DC block capacitors) that using LTspice.
It had f0= 200kHz +/- 100kHz of bandpass filter characteristics.
When we apply CW to the RF input, Logamp input will appear twin peaks of signal because RBW filter has bandpass characteristics.
I think your demonstration of 145.55MHz CW agree to my estimation.
Because I seen the frequency difference between peak to peak is 400kHz (=200kHz*2) in your video.
I got additional idea from these consideration.
It is TG (Tracking Generator) offset frequency.
In DCR idea, if LO and TG sweep with the same frequency, mixer output will be DC voltage.
In this spectrum analyzer, we cannot see frequency spectrum because DC block capacitor blocks DC voltage.
So in this spectrum analyzer, TG (become RF signal) and LO frequency should have offset value such as 200kHz.
Amazing explanation! I was trying to figure out what was causing the notch. This design was used to simplify the mixing stage, using just one, in contrast to "conventional", or "real" spectrum analyzers that uses two or more mixing stages, right?
Thank you so much Andreas!! Lovely video. Thanks for your time.
yes, he has very cool videos
You are welcome!
5:48 _natural sine wave generator_ 😄
1570 Hz (by Android apk) ;o)
So it was a bit over the 1k signal...
Freaked my dog out
Thank you for yet another very interesting video! The testing, the explanations and the conclusions at the end are all very valuable. Thank you!
You are welcome!
I appreciates how you do the comparison in a very in-depth details. I works as a RF engineer and always find myself lacking in many area. This information is very useful to me on how normal practices are done based on different people and their background. Thanks man!
Glad it was helpful!
Perfect timing. I just ordered two BF-F8HP radios last week and started studying for my technician license. This week I learned about antennas, SWR meters, and the NanoVNA. So much new information introduced to me in such a short time I feel like I am in college again. Thanks for making this video to supplement what I am already trying to learn.
Seems you are on the right track!
You are incredibly talenful in teaching and explaining things in a way that makes it easy to understand.
Thank you!
Thx for the walkthru, well done and I love how you link and make due diligence on these products and link to the relevant parts, that a possible owner can benefit from.(golden)
many other channels can learn from the "viewer perspective-awareness" you seem to suit your videos with.
well done Andreas. +1
Don't have this Spectrum analyzer but were looking into it as an entry tool to just get familiar with this kind of class apparatus.
at around 30 bucks delivered for this unit (no shell), alternatives are not hanging on the threes in this sub 100 bucks environment.
You are right: For sure it is good as an education device. And knowing this technology is important for many projects
Excellent presentation and explanations Mr. Andreas. Keep sharing your knowledge and we will enhance our world one step at a time!
Thank you for your nice words!
I was about to buy one of these 50 dollars spectrum analyzer, but after seeing this video I changed my mine. Thanks Andreas Spiess
You are welcome!
If I understand everything correctly then this spectrum analyzer uses an low IF frequency of ~few hundred kHz, most spectrum analyzers use high IF that is higher than maximum frequency they can measure. Because of that it is going to see signals that are centered at LO +/- few hundred kHz and that's why there are 2 peaks when you measure signal of that handheld. That's very bad because some signals, like signal from that handheld will appear to occupy twice the bandwidth and have a weird notch in the middle as seen on the video.
Exactly! But for 50 dollars an IF above 4GHz including filters is probably still not possible.
I used my R&S FSEA20 analyzers almost every day for a seven year period. I got pretty used to these high performance machines that had a noise floor of about -160 dBM at zero span. Made my job easy. These days those analyzers can be had for about 1500 bucks in good working order.
You are right. I see a lot of people buying these old instruments. They are a very good choice if you have enough space and maybe also some knowledge to use/repair them. For you, as a long-time user, this is a perfect fit and not comparable with such a cheap device...
Thanks! I was looking at such a very device just the other day to analyse my antenna design. It's really cool that you showed another device @9m30s that is probably more what I was looking for. Thank you for your good quality videos.
You are welcome!
Great videos :) Love the artificial hand...lol You have a great sense of humor along with great tech knowledge... Thanks for making it so much fun to watch.
Thank you for your nice words!
Thank you again for the high quality video! I was thinking about getting one of these, I'm glad to know exactly what the limitations are.
You are welcome! This was exactly the reason for that video...
The limitations are not what you see in the video.
Very nice video again! You make my day, because I learn several new things and that is a must for me. Thank you Andreas!
I try to add some value to my test videos. Like that I hope it is easier for the viewer to decide if someting is good or bad for his application.
Thanks for the video. Very helpful… and your lab assistant napping at the end is great.
Glad it was helpful!
You could say that the Mixer is a Multiplier.
If you remember your trigonometry: sin(a)* sin(b) =
(cos(a − b) − cos(a + b))/2
This is why the sum and difference of frequencies appear.
In practice the Mixer is not perfect and there are nonlinearities that generates also harmonics so you get N*a + M*b (with N and M integers). But the other frequencies and usually much attenuated with a good Mixer.
And if you want to know how to multiply signals:
th-cam.com/video/7nmmb0pqTU0/w-d-xo.html
You are, of course, right. For my videos I usually need more time to "leave things out" than to "put things in"...
@@AndreasSpiess I understand that just putting a trigonometry formula in a video can scare people 😆
I'm not a RF guy at all but I find that part of electronics quite stimulating.
I just wanted to add some extra for the curious ones that asked themselves "how does a mixer work?"...
BTW: Your link points to a very good channel...
I love the little 🖐, pointing out things 😂
:-)
Me too. Where did you buy it?
This was a great video. You explained everything so well. Thanks!
You are welcome!
Yes, yes Andreas is a good communicator
Excellent video, as usual, thanks very much, Andreas. That German "Tiefpaßfilter" should be at least 24 years old as it is written "Tiefpassfilter" since 1996. Now I know what a spelling reform is good for.
Interesting. Frequencies still are the same today...
In my small lab I have an anti static workstation. Earthing, wrist strap points etc. Grounding for me, my equipment and soldering station. The sight of the purring cat is cute. Except all I could think of was "THE STATIC!".
She is for sure not helpful to prevent static charges, you are right!
Always looking forward to hearing from you! I’m not into RF much myself (except when having to filter harmonics, hee hee), but your videos are always didactically well prepared so it’s pure joy watching them and there’s always something to learn. And of course I dig cat-lovers, having had my own lab cat for ever so many years. :-)
Anyways, thanks for being there, doing all this and even teaching an old fart new tricks from time to time!
I am an old fart, too. And Dishka, too. So we are already three. She, however, seems not to be too interested in learning new tricks...
Before Spectrum Analyzers we had Frequency Selective Voltage meters. Aka the most expensive AM Radio's in the world. Cool Video yet again Sir.
This was probably many years ago... But they did the job. And many awesome projects were done in this time.
TLDR It works but you get what you paid for. Thorough video again by Andreas!
I still think, we get quite a lot for 50 dollars. Those new AD chips really make it easy to build interesting things...
Cat found the best spot for a snap :D
This is why I need three monitors. One is no more usable...
Relearned the term "tracking generator" from school, but these days you might as well get an SDR in that price range.
As I mentioned, the SDRs are not exactly the same. If you want one with transmit you are in a higher proce range.
wow this is so cool. I am starting to check out how to build a SDR radio telescope and one video used a cheap spectrum analyzer test the 21cm astronomy hydrogen line.
This is a all new learning curve on making a homemade radio telescope using SDR software. 😎 thanks a lot.
Check the newest link in the description before you buy a TinySA. There is a new version available.
@@AndreasSpiess I checked it out and ordered a: tinySA ULTRA 100k-5.3GHz Hand held tiny Spectrum Analyzer + 4" TFT LCD +Battery. Thank you very much.
You saved me $50. I might have bought this for fun. Also from the comments I learned that the Germans have abandoned the old version of "ss" which I learned back in the 1970-s. The "sharp s" which it was called here. (Where is it on my keybord?)
AFAIK it is still on their keaboard. We Swiss never needed it ;-)
I like the way you reply to each comment. Keep going
Thank you!
I think that the 'notch' is not RBW-related issue, but due to the LO 'step', since it appears that the design does not actually 'sweep', but uses discrete step sizes, or?
It's because when the frequency of the LO is exactly the same as the input frequency the output of the mixer is DC and the logarithmic amplifier does not amplify DC or very low frequency, also because of capacitor C29 which blocks any DC into the amplifier anyway. As the LO moves slightly above or below the input frequency then the frequency of the output from the mixer is again high enough to pass through C29 and for the AD8307 to amplify it. Apart from the notch this design has another flaw, that of 'reflections'. If for instance you were to look at an SSB signal it would appear as a double sideband one with suppressed carrier.
In 'real' spectrum analysers they do not convert to DC but instead to an intermediate frequency of a few MHz and then measure the amplitude of that. That also eliminates the reflection problem.
@@listerdave1240 Thank you for explaining this phenomenon.
This "notch" didn't make much sense given the theoretical principle of operation.
BTW, isn't C18 also a problem?
@@listerdave1240 The AD8307 can handle up to 500MHz. An IF around 450MHz would stay well within the specs of the 8307 and make it easier to design the image rejection filter.
@@listerdave1240 This makes alot of sense. Why couldn't they just down convert to a constant IF like in any good old superheterodyne receiver? Then using a narrow band amp with filters would also filter out the odd integer multiples due to the square waveform of the LO. Yeah I realize this 50 bucks spend wasn't worth it's bang ...
Andreas, thank you for your outstanding work! Please, will you PLEASE update your Links at the bottom? Sadly a number of them no longer connect. Thank you again!
With 400 videos I cannot update all links :-( But I updated the link to the TinySA
Thanks. Useful pointers here of what to look for in a cheap analyser.
As I like to say, I would RTFM, but there was no FM to R.
Documentation and software is not a strength of Chinese manufacturers, you are right.
The solution of removing the display and just add an USB control makes instruments cheaper and, more importantly, smaller. I've made several USB instruments under the same principle. Actually, the video caught my attention because of this.
Anyway, loved the video and also subscribed. Thanks for sharing!
Welcome aboard the channel!
I made a receiver with tracking ADF synth and nextion display some years ago. To have a flat power signal, I had to add an amplifier and a step attenuator (controlled by µC). It has to be calibrated ! Now I have +/- 1dB precision. (compared to my keysight at work)
Sounds like a nice project! All possible with today's cheap ICs. And a good instrument for calibration ;-)
Super interesting & my dog jumped from her bed & started barking at your whistle, so we both got something from your video. Thanks for sharing!
:-)) You are welcome!
Hi Andreas, some time ago I bought one of this chip device. I compared features wit a R&S in office lab: agree with your conclusion ...
About SW, I tried to be in touch with the original designer but ( I can 100% understand why ) I did not receive an answer. Any way, googling and spent some time reading forum, I found Python driver and commands list ...
... but all is sleeping since "The job is not worth it"
I tried to reach the author too with no success. The software could be so much more improved.
Thanks for the video Andreas. My radio club bought a Rigol Spectrum analyser a few months ago and I wanted something similar for my little work bench and having found this on ebay thought it was a good little project ( I bought the naked board). I've only yesterday finished putting it into a case with N connectors and will be keen to try the new software. Love the cat on keyboard :-) Keep up the vid's, It's good to see a ham doing such a diverse range of topics.
For HAMs a nanoVNA maybe is a better choice to measure antennas and filters. I hope your SA will do the job.
Thank you for quality information. I'm using sdr + white noise Zener + spektrum software to align homemade vhf filters. Regarding my application my setup performs similar to NWT. At the end nothing can replace a good sigilent anritsu Hp spectrum analizer. Thanks again !!!
The new cheap VNAs are a handy replacement for antenna design in my opinion. And affordable for most.
Good video. I had a look at this cheap device a few weeks back, my mouse cursor hovered over the 'buy now' button.
After watching this review i decided NOT to buy it, save up more money for a proper one. This video saved me $55 and disapointement. Thank you Andreas !!
You are welcome. Decisions like that are the purpose of this video...
Amazing how cheap things can be when the core functionality can be implemented in software.
And excellent chips can be bought from Analog Devices for nothing...
NWT4000 DOES NOT RECOGNIZE THE LTDZ 35MHZ 4400MHZ SPECTRUM ANALYZER?
I understood the first and the last couple of minutes. Most important component is a furry oscillator.
"Furry oscillator"! Man, I almost spit my coffee against the screen laughing … have to remember that one! :-) :D
@Malt :-)) You got all you need, I think ;-)
Very usefull tutorial about Spectrum Analyzer .. the natural sinewave generator is a must and cat is paying atention even "sleeping".
Yes, she usually does not sleep. She just "rests"...
I love that tiny helping hand
:-)
At 18:10 I think you made a mistake.
Settings on Siglent are RBW 1MHz and att 20dB. This gives noise floor of instrument (as seen) around -45dBm.
It can not measure beyond that and we see that smooth trace goes into noise.
I assume that if you disconnected filter, noise floor will stay about -45dBm.
Also at 8:20 you hit the noise floor of Siglent when measuring notch filter.
Good LPF should have much greater out of band attenuation.
Cheep analyser has noise floor at -70dBm as we can see.
Please redo measurements with appropriate settings on Siglent.
If I am wrong, please accept my apology. I don't own Siglent spectrum analyser to check by myself.
Thank you for the correction!
Thank you for this excellent review! I have a spare Agilent 6ghz directional coupler and plan to get this for a friend who needs to measure SWR for his home-built 3.5ghz 5G-antenna. It lacks speed and resolution as a spectrum analyzer, but I hope it works fine for plotting S11 curve.
I like the VNA to measure S11. But a SA should also work.
Thanks a lot Andreas, I will give it a go :)
I recently purchased a miniSA spectrum analyzer. I am
Sure you’ve seen it. It is not all that different than the miniVNA. I would love to see you analysis of it and show too it’s usefulness and it’s weaknesses.
You find a few very good videos on TH-cam. It seems to be much better than the one here...
Probably my favorite video among all your great quality tutorials! But what does the VBW indication on your Siglent screen correspond to?
The explanation is here: www.siglenteu.com/application-note/spectrum-analyzer-basics-bandwidth/
Tnx for nice explenation! Got it: the FIXED Resolution Band Width!
:-)
I also would have enjoyed seeing the cat's purring on an audio spectrum analyzer's display output!
Maybe stuff for another video...
Excellent video as always!
Two quick things...
The link to the VNA video in the description is pointing to Amazon, not TH-cam.
Did you do a video comparing the nanoVNA to the other VNA?
I thought you had, but I can't find it.
I changed the link now. Thanks. And I did not do a comparison of the nanoVNA. There are quite a few videos out already and I still think, the N1201SA is the better deal for ISM band guys. I wait for the successor which will also cover more than 900 MHz with a decent resolution.
Thanks for the great video! After this video I bought this analyzer! I am a developer for electronic devices and I think this device helps me. Lg Szivatz.at from Austria
Glad you like it!
Thanks for the video! I found it really informative. I probably would have wanted one of these had I seen them for sale, but as I mostly would use it to measure harmonics from transceivers they are kinda useless. I think for cheap harmonics measurements an SDR dongle and attenuator is the way to go. I already have a Nano VNA for checking filters and antennas.
You are right.
I would like to buy a spectrum analyzer for 2 reasons: 1-to familiarize myself with spectrum analyzers 2- find FM and LTE signals strenght for interference when I install antennas to be able to determine if FM or LTE traps should be used.Could the cheap one do the job?
Another very useful video thank-you. 2 years on I was hoping perhaps you had covered the Tiny SA spectrum analyser but could not find it on your page. I would be very interested to know how you find it.
It seems to be a good device. There are a few very instructional videos on TH-cam. I think they are from the programmer of the firmware.
@@AndreasSpiess Thanks for the reply. I have seen some videos. I was interested in how you personally found them. I think they are worth a try at the price.
@@acestudioscouk-Ace-G0ACE I have a Siglent Spectrum Analyzer on my desk. So I did not use the tinySSA a lot.
Thank you Guy with a swiss accent. I visited Luzerne for 1 day. At night. It was okay. :) I want a spectrum analyzer. I don't have a use for it right off the top of my head but I would find a reason. Not swiss mentality but hey... this is internet.
I also have bought a few things like that ;-)
Thanks Andreas a good informative video. I just purchased a unit off AliExpress not the same one you have here but its labled 35-4400MHz with a IN and OUT port and USB port. I hope it will work well for monitoring a wideband Digital DVB-S2/T ATV transmission at 1255 MHz...love your puscat I have a long hair pus too...Cheers Clint - VK3CSJ...
Usually these devices are not used as receivers. They are more used to measure emissions... 73 de Andreas, HB9BLA
Very good job Andreas, nice presentation and very useful, tanks you...!
Glad you enjoyed it!
Excellent explanations. Thank you
You are welcome!
I am French. Can you confirm that the voice-over of this video is in English? I have a big doubt because I understood everything without problem!
I have rarely seen a video of this quality on TH-cam, both technically and in terms of video editing and sound recording ... and with so much humor!
This is a very nice comment! Thank you. French nearly "killed" my career when I was young because of the bad grades. I only learned it when I worked in Cameroon... But since then I forgot most of it. Good that we can communicate in English.
Keep watching Andreas and prepare to learn a lot!
@@AndreasSpiess Oh mon dieux c'est incroyable
wonderful explanation on a Spectrum analyzer. Thanks ✨✌😊
You are welcome!
Thank you for another great video. I wish to see more episodes related to RF signals and ham radio. Vy 73!
This is not ham channel. It focusses on the ISM usage of RF because only a very few of my viewers are HAMs. Maybe I can motivate a few ISM guys go get licensed...
Excellent educational presentation, bromigo!
Thank you!
Fantastic video! Thank you!
Glad you liked it!
Perhaps it is mentioned, but I didn't got it. Can this analyzer work as a tracking generator, e.g. for bode plotting?
I do not know a lot of bode diagrams. But the device has a built-in tracking generator. Mind the minimal frequency if you would like to use it for audio.
I hope that they continue to improve the device.
Let's hope...
Nice SA overview; i did think that you might add that one often uses a noise source, instead of a tracking generator, since it removes a couple of 'dependencies', but, that's a bit picky... i see that you mentioned the noise source right at the end!
Sad, how often some inventive person's work becomes just one more source of a chinese company's income :-( When I was in Helsinki, i visited a showroom of "Finnish Design", showing off the truly-great breadth and quality of art, artisanship, and inventiveness of the people of this country of only 5.5 million people (a shameless plug for them! ), and, what do I see? A small group of mainland chinese (i recognised the mandarin language) , walking around, taking photographs of items... not just a 'snapshot', either, but pictures from every possible angle. Obviously, not just a 'tourist photo', they intended to go home, make a copy, and sell a few million.
So, even when it's not 'visible', we may find the nice work of some German, Swiss, Canadian, Finn, at the heart of some chinese gear that is so inexpensive that we canpt avoid buying it...or, can we? Still, it would be a nice surprise for some German, or Swiss, ham person, to receive a few Euros/CHF in his bank or paypal, or 5€ in the post :-) !! itps just a thought....
I remember the 1980s where the Japanese did the same with our products. Nothing new. Switzerland still exists because we are very innovative. The same will happen again and again, I think. This is how the world moves. We were the leading country in textiles 100 years age...
As you mention we can send these people a few Euros if we want. Like my patreons do it with this channel, for example.
That whistling bounced off my walls and really creeped me out.
Please do a video on SDRs and clever configurable (elegant design and possibly cheap using HEMTs/GaN) front ends. I was hoping for a bit more of a deep dive into that sort of thing when I was notified of this video.
For 50$? GaN? Maybe in a few years...
@@AndreasSpiess $50? I'm confused as to the number you came up with as well as the significance-- I just would like to see an exploration of HEMTs before they're commonplace. Also, GaN transistors aren't very expensive now and they are underrepresented in enthusiasts' communities, so I thought you'd have an opportunity to deep dive where no man had before. It's ripe for clever approaches.
@@AndreasSpiess GaN transistors are cheap and extremely capable (maybe you were thinking of SiC?)-- for instance: www.digikey.com/products/en?WT.z_cid=sp_917_buynow&keywords=917-1153-1-ND
I thought your comment was about a device using this new technology ;-) I am no specialist in this and I also think it would be too special for this channel. Maybe others will cover it.
in summary:
the price difference has its weight, then it depends on the use you want to make of it.
$ 3,000 is a great investment for a hobby, so the $ 50 device might be enough, once you compare it to some more advanced device ( hoping you can do it) you have a "touchstone" for your purposes.
If, on the other hand, you have to study the behavior of various equipment rigorously, perhaps for work, then you must think of a quality product such as Siglent or of equal quality.
Tnx for yours intersting videos Andreas and i'll see you next time!
I most probably will not do a SA comparison on this channel. There are other channels focused on this topic. I just wanted to give some advice to people hoping they can save 2850$ to go to this cheap device ;-) And they should know a little on what they have to look if they buy another one.
@ Andreas Spiess: I completely agree with you: I was also a radio amateur, and I never had a spectrum analyzer .. in reality I was more of a CB than a real radio amateur (even if I had acquired a license and license: my name was Ik4DZF but some time has passed ... 20-25 years !!) and when I built the jpole for 144 MHz I went by attempts trying to respect the project's measurements ... it worked , at least to get on 144MHz repeaters :-)
About as expected for $50. But I would just go buy used SA off ebay. You can get some really incredible ones for very cheap. Devices which used to cost $150,000 can be purchased for only ~$500. Lesson learned: expensive high end lab test equipment doesn't retain any value and depreciates worse than even the worst automobile.
You are rright. Especially spectrum analyzers. The Siglent is also only 3000 Euros for 3.2GHz. Costed also a fortune a few years back ;-)
Would be nice to see you show this with an SDR, it eliminates some of the issues shown here (probably adds new different issues).
You can use Spektrum made by Pavels on GitHub, I've helped on the development so if you have any question you can shoot me an email !
Spectrum analyzers do not measure phase as tthe VNAs do. So they are slightly different. I prefer VNAs for Antenna work.
Very Interesting and useful. I was wondering if it would be possible to use one of these to perform Prequalification EMC / EMI RF tests in a DIY TEK cell. Or perhaps there might be some other way to get an idea before spending $$
They are not very sensitive. And for sure not precise. If your application can live with that you are good to go.. I doubt it.
Please a video about using SDR as Spectrum analyser :)
Maybe later...
@@AndreasSpiess Yes please
Thank you, That was one of my questions I posted some videos ago!
:-)
Buyer beware. If you only need a *cheap* spectrum analyzer, get yourself a used RSP1 or RSP2 for about 100 € or even less and the spectrum analyzer software from sdrplay. Pretty accurate and much more sensitive than this crap here, although it is not as fast as a real spectrum analyzer. Andreas, well done this video!
I agree.
Thanks Andreas
You are welcome!
I defenately liked this one ! Excellent and well described !
Thank you!
Thanks Andreas. I'm interested in testing an area to find out what radio frequencies and signal strengths are present. What would be the most cost-effective way to approach this problem?
A spectrum analyzer is good. Or an SDR radio.
@@AndreasSpiess How much would you need to spend on either of these technologies in order to get something reliable and useful? Do you have any brands/models to recommend?
Very good info..I subscribed and plan to watch more vids. I have added some external filters and a 30db wide band LNA on the input of mine. It has made the spectrum analyzer more useable. It’s still not great, but much better. I also did clean up the Power supply and did the mods going around on the net. I added a variable attenuator on the in and TG out along with the ext Amps. I packed it a nice shielded cabinet its not as good as a real network analyzer, but it is actually useful now. I actually made a selectable multi filter selection for different band widths. The stock internal filtering was pretty bad. I may try to do some more improvements? We will see? Too many pokers in the fire. Great channel. I enjoyed watching.
Welcome aboard the channel! You invested quite some effort¨. Maybe you document it for others to follow?
Andreas Spiess . Thank you sir. I will try to put together all my info on the mods i made. Its pretty much chicken scratch now, but i will try to compile it i to something intelligible. I will be watching and i will let the channel know when i have good information to share. Thank you for the warm welcome.
Andreas I have done similar experiments with the same Banggood device. What struck me first was that the tracking generator produces more or less a square waveform. Presumably same is true for the LO since it uses the same chip. So the mixing products must contain odd harmonics of the LO. I also observed the dip when trying to display a single carrier tone. You have any idea what it's causing it? It almost looks like as if both side frequencies contribute to whatever is "measured". The symmetry kindof gives it away. BTW I like your cat :)
Viewer Allen Edwards below gives an explanation for the notch. Concerning square wave: You are right. But because the LO sweeps with the TG it (usually) does not see these harmonics. I mentioned that the Siglent has more filters. This is where some of them are. Its TG creates a sine...
Kind of neat but that false notch renders the device useless in my opinion. Better to buy an old second hand SA. Thanks for the video Andreas 👍
I didn't quite understand where that false notch comes from. It is also quite prominent at the more detailed scan.
Edit: Lister Dave's comment bellow explains it nicely. There is C29 capacitor that removes the very DC we want to measure. I Think that C18 may do the same.
th-cam.com/video/PRsaGEk-EsQ/w-d-xo.html&lc=UgyDM9iflCNIOa0WzXV4AaABAg.95NRn9Qnwem95NTJCzMq0w
Unfortunatley you do not find old instruments in all countries. They are often sold in the US, and transport can become quite a problem for such heavy things :-(
Thanks! I was considering buying one but my LimeSDR is much better, I'll stick with that
You a re for sure not bad witrh a LimeSDR ;-)
Great Sir! I guess it will be a good instrument to design antenna
As I mentioned. For antenna tuning, a VNA is a much better tool
I am sorry watching this video so late - have to be on a HAM-Fest at 9:30 here in Berlin today and bought 2 things to play with .... may be you should mention the cat-content at the end by your overview in the beginning - so viewers stay till the end.
I hope you liked the HAM fest! And maybe found a few interesting things. Concerning the cat: I think it should remain a "surprise" for the guys who stick to the end...
Wonderful video! Useful & neat!
Thank you!
I LOVE the pointer.
:-)
Awesome, thanks Andreas!
You are welcome!
I ❤ the Mini Me FINGER. Just saying. Good show (you can take my word for it)
🇺🇸
Thank you!
YOU ARE AMAZING ! thanks for good content
You are welcome!
I nearly won a Tektronix 7613 for €20.00. I think it is obsolete but do you think is pointless to buy one of these according to the cheap spectrum analyzers you can get nowadays? I think this is very good for ELF from 1Hz onwards and I am interested in studying the brainwaves
The professional SAs are much better than these small ones, of course. If you get a working one for 20$ and you have the space for it, very good!
Very nice and explorative video. Did you try the snasharp software???
I did not know it. But now I tried. Unfortunately I also was not successful. I tried to calibrate the SA and then measure the very same configuration. I would have expected to see 0 dBm across the spectrum. Unfortunately II did not see anything like that. :-(
Danke fürs Erklären! Haben Sie auch noch einen deutschen Kanal? Mit Englisch tue ich mich ein bisschen schwer.
Bitte, gern geschehen. Und nein, ich habe kaum Zeit für diesen Kanal :-(