Hi welcome to Tear Down Tuesday We're going to take a look at the brand spanking new just on the market sigin SSA 3021 X and click here if you haven't seen the uh comparison of this against the Ryo Uh 815. so I've done a video on that. let's Crack It open. Now for those playing along at home, this is the new hardware.

The latest one that has been uh, redesigned cuz they had a few issues late last year. They had to redesign this thing so this is the latest one 2016 build. Got a couple of screws on the top here and on the bottom. Uh, just like the Ryo units screwed in exactly the same way.

Yeah, and we can make short work of this security sticker with an antistatic bag here. I've done a separate video on that. click here to check it out. and yes, I have a bit of thread Locker on the screws.

As is common, there's a couple of little Clips there that you have to get off and once we do that, well, let's crack it open and tada, we're in like Flynn There's our shielding. and yes, it's the exact same sheet steel construction as we've seen in other signant gear, which is prone to rusting along the uh, cut edges. the famous siglent rust. Um, and we've got Pop River tier.

Yeah, it's You know it's not a full aluminium shazzy. So yeah, that's not great. But you got to remember that the uh, main competitor of the Ryo 815 is no different. It's exactly the same, uh, sheet metal outer construction.

We're going to have the alum block inside it for the Uh RF shielding. Is it my imagination or is there a little Teensy wensy bit of trademark signant rust there? It's really hard to see, but yeah, there's not much but these um, edges if they're not treated properly. yeah, they're prone to it. You can see they do have proper RFI shielding tabs down there for the Ethernet and the USB No worries.

All right, let's pop this off. We're going to have uh one main board I'm sure as is quite common, that would be my guess with hey, there's our shielding blocks. We got at least two shielding blocks Excuse me. While I disconnect the power cable here we go I'll swing it around for you.

There we go. No, we got a separate wall. no one main board here, separate RF board and then another section down here. There we go.

We're in like Flynn and if we have a look at the mains input down in there bit hard to see but they've got that properly heat shrunk and crimped and Shake proof washer onto the Shazis. No worries whatsoever and the power supply looks neat and tidy. Does have Siglent brand whether or not Siglent actually designed and engineered and built the thing I don't know they could have shopped it out is as is very common in the industry, Lelon brand cap grown. you know it's the main DC input uh filter cap gets less stress.

We'll have to have a look at the output ones there, but nice strapping over there looks nice and tidy. They've uh, sasti down the output caps but it just looks decent. design and build quality. No worries I think just be able to see Rubycon caps down there.

So yeah, they're decent. now. this is actually significantly different to the Ryo one which had as I mentioned, a single board. uh construction like this.

This has got three separate boards here and well I don't blame them at all. We've got our main processor board down here Spartan 6 Fpga We'll have a look at the chips on here. more detail. Got an application processor and you know, pretty Joe blogs, uh stuff and then this has a what probably is the uh oscillator for the thing I would say would be over here and they're driving that.

but then we've got our um, our input is over here like this and then it flows through all the various stages that a spectrum analyzer needs. And of course, this separate block down here is going to be the tracking generator. They've done that as a physically separate board and they've just got uh, the, you know .1 in IDC header cables going over here. That's no problem cuz these aren't carrying any significant.

they're carrying some power and just some. You know, control signals and things like that so you know you don't have to worry about that inside these blocks. Here you'd have some uh, power supply decoupling, local regulation, and things like that, some inductors to filter out crap and all that sort of stuff coming back in and out of these two uh blocks here. But yeah, that's just fine and dandy.

uh. power supply section down here? No worries. Better than the Ryo 81 5. If you have a look at that tear down video, you notice they had like a freestanding heat sink and it was all a bit how you do and this one's a bit more uh, polished.

So yeah, it looks good. And I think we can get right into this block here taking out the screws without taking out the board here. There's a couple of longer ones which go into support support post on the bottom. There's another aluminium block on the bottom, but uh, let's lift it up.

We've got our gold flash around the edges Tada We're in like Flynn and yep, as I suspected, here is our OS It looks like we got two of them and these are super dup. Well one of them is going to be super duper special cuz this one's pretty. Schmick Oscillator Much better than the Uh Ryol 815 that we saw in the Uh comparison video. It looks like they have a dual footprint there.

So uh, let's take a look at this all right now. We can have a look around the main board here with our Tano microscope. We can zoom into our heart's content. Let's uh, start with the boring stuff.

Nothing exciting around here at all unless switch mode. power supplies, float your boat. there's a switching controller there, dead giveaway with all the uh, inductors around here and everything else. So and then some big sort of power tracers going to the inductors.

uh, that's probably a multi- channel job. What is it? 3.3 Ox yeah, 3.3 all around there. Not much doing around here. Mel Good to see Mel I'm a bit of a Mel Fanboy myself and uh yeah, not a huge amount else happening everyone.

Come On Dave Show us this is the Um LCD connector going off. You can tell by the Twisted pairs. the reason they need Twisters pairs is because they're highspeed serial interface and we got ourselves a Spartan 6 XC 6s lx45 um Spartan 6 was also used inside the Riyo 815 as well I can't recall off hand if it was the exact same one unpopulated memory, uh, footprint here. They didn't need it.

Anyway, the Spartan 6 Fpga you know, reasonably pedestrian, uh, Fpga sort of middle of the range type stuff. It' be doing all the Fft, uh, processing and things like that. That's what. uh, Fpga are really, really good at and can't see that number very well.

It's all about the light, by the way. seen part numbers, all about the lights and the angle. Anyway, we got a TI part and if I Shield the light from this side with my hand, there it is the Am 335 too. that's an Arm Cortex uh A8 processor.

You know, the typical thing that'll run Linux and uh, everything else. No worries, it's got Wisbang 3D Graphics in it and all that sort of stuff. anyway. I'm not fussed over those.

and then we got our uh, looks like we some Samsung uh DDR memory here by the looks of it. and there's our flash program memory. We've got ourselves very nice. We got ourselves a j tag uh header up here.

so Bingo you can, uh, whack that straight in. probably does uh. both devices I would say there might be daisy chaining those together cuz I can't see one for the is there one down. Is there one down here? somewhere for the uh processor I don't think so.

This would be a test connector or something would be my guess. I''d be using that for some sort of uh production system testing. but uh, it's interesting to note what device is missing up here. U14 Um, that's fascinating.

It's got an external Crystal just a HC 49 uh Crystal there. and yeah, it's got a thermal pad on the bottom. Um, so it's doing something reasonably serious. I'm not sure what.

why did they leave that unpopulated? Where's Wally I Think What everyone wants to see though, is this marvelous oscillator they got inside this thing. Oh well, it's not marvelous. Not like a, you know, a uh, oven controlled oscillator or rubidium or anything fancy pancy, but you know it's a decent spec. Now who that is? Um, there's our 10.

that's our main 10 MHz reference. So uh, yeah, by all means, try and decode that part number and get that. who actually makes that I don't know, let me Google it. Well, that doesn't.

uh, show up anything unless I do uh, some more exhaustive searching I'm afraid not much I can do there. Sorry about the glare, but that's the only way we can get the part number on these puppies. These are Mcrel 5209 I've used those before. they're uh, low noise low Dropout Regulators not bad little things so nothing else.

much doing. discreet trenny or two. no workers. but what is U16 over here and that one right there.

bit of magic happening. bit hard to make out, but that's an Analog Devices ADF 41. And here's the data sheet for the ADF 41 from Analog Devices 200 Meg Clock Generator PLL But uh, look at this. it's a P that requires um for clock sources that require very low noise, stable reference signals.

it's ultra low phase noise and that's you know what we're getting in this thing I Mean it's not a industry leading uh Spectrum analyzer by any stretch of the imagination, but it's uh, certainly better than the Uh ryol. And as always, I'll link in the data sheets down below for those who want to, uh, take a quick look at it. But uh yeah, it's a pretty decent uh P I like it and pin six here you can can see coming through the firewall here all the way over to this 40 MHz oscillator over here. So this is the PIN six is the RF input to that so there that is coming directly from the crystal over here.

and of course the 10 mahz reference will be going um into the main uh clock input for this thing. and I really like the way that they've done this tracking generator module here. you'll notice that all these numbers 1 one, one, one one, these are the uh long screws which uh, as I said for the previous board, go right down into mounts on the bottom here and two and two is obviously made in up with the Uh end connector on the front. and once I've taken out all these ones actually sorry there we go taken out.

Oh what's that one? No, that one's got no number. so I've taken out all that entire module pops out like that. isn't that beautiful. Nice bit of engineering.

Love it and you'll notice the PCB as well look. Gold plating on the the edge in castellation is like a half moon on the um, you know if you do like a drill on the uh side of the thing, but uh yeah, that's a separate manufacturing process. You can get most PCB manufacturers to actually do that. You just need to specify that, uh, separately.

I'll have the edges gold plated. thank you very much, but obviously they've penalized it. There's going to be a break in, uh, that there, so maybe they uh, do. Oh no, that's just around the connectors there.

But anyway, that's just nice. Like a separate block like that makes it real easy to design. real easy to change the design if you had to. like.

If they had to respin this, you know they had an issue with it. They only have to respin this. They don't have to respin the the main RF board up here. the whole, you know, the whole shebang.

They can just do the tracking generator. It's just much nicer from an engineering point of view. modular based like that. whereas the Ryo one as we've seen in the R 10 down completely different.

It's all on one board. Everything that makes it much more difficult to respin. Potenti Po lower cost, but this one, it's going to be higher cost. uh, potentially little bit.

you know there's not a huge amount in it, but potentially higher cost. but yeah, it's just nicer design. Time for the reveal Tada What do we got on the top? There we go. Oh yeah, baby.

Some RF magic and on the bottom side? More? No, not as much RF magic happening there. In fact, it's just boring. Some passives. All the magic happens on the top and this sort of stuff looks like RF Voodoo RF Magic.

but it's not. I've mentioned these in the videos before. these are just distributed element filters. They're basically LC Andr filters.

That's basically all they are because these elements at RF high frequencies. uh, look like that. Trace There for example, is an inductor this big Square here is a capacitor cuz there's going to be a ground plane on on the layer under this Uh controlled dialectric board. By the way, this would be a, you know, some maybe a Rogers brand or something controlled dialectric constant.

so it's just has more controlled Uh frequency characteristics over controlled impedance characteristics over the Uh wide frequency range. So this will be a capacitor directly down to ground. We'll have another inductor, another capacitor, another inductor, another capacitor, another inductor, another inductor in series with a capacitor going down the ground, an inductor tin, smaller inductor much smaller than this one here in value, and then larger capacitors going down the ground inductor, inductor, capacitor, inductor, and so on. It's going to be a distributed element low pass filter.

There's no magic in there, and a similar sort of thing is happening here as well. We've got another Uh distributed element low pass filter. Once again, we've got the Uh Mcel. They're using these everywhere these 5209 um for low noise, uh, local voltage regulation and and uh, then we've got a few other Oh 74, Is that a 74 Hc4? There you go.

You got to have some Uh 7400 series uh TTL in there magic And you got to have a classic Tl72 Opam as well. But of course it's not doing anything. uh, you know, high performance. It's just doing an offset thing or you know, something like that.

So it's no big deal. It's not working at Uh frequency, it's just maybe doing some uh uh DC type stuff. And we've got a HMC 307. This is from Hitte now owned by Analog Devices It um, looks like it's an obsolete part, but that's actually a Uh digital attenuator.

And when you go into the Siglent tracking generator software and you can set the Um attenuation value of the Uh tracking generator anywhere from 1db. Uh, in this particular case, the chip goes from 1 1db steps up to Uh 31d DB attenuation. So that's how it's doing it. Very simple.

Now, of course, there's no clock on this board because the Uh Tracking generator is does exactly what it says it tracks. so it's uh designed to take whatever the current uh sweep frequency is as the Uh Spectrum analyzer is. You know, sweeping across from whatever, uh, your start frequency to your stop frequency, then this, uh, just designed to track that it generates um, the same frequency as what it's uh tracking. So that's why it doesn't need its own uh oscillator.

that's why the frequency? um, well, does it come in here or does it pop out there? Not entirely sure Anyway, which one's what? which is in which is out? doesn't matter. And of course, no surprises for finding another Hite part here. which is the uh PLL This is exactly what you expect in here. Um, goes up to 3 gig a reasonably capable part there.

so that would uh, that's generating the uh, the main tracking clock you might be wondering about. These also got H in front of it. look 860 835 We looked at over here. we've got an 860 and we got a H uh 976 here.

These don't look like of course, anything high frequency sort of going into them or anything like that. and you know, lots of bypass caps around them like zero ohm resistors. Not much else. Um, what are they? They're actually linear voltage Regulators they are from um Hite uh, of course, but their you know, specifically, high power supply rejection ratio.

uh psrr um of course. uh, low Dropout voltage Regulators So there you go. They use the specific Hite ones which are would have been recommended possibly in the data sheet for this. Um, even though I haven't had a look for that, you know that's probably where they came from.

They're specifically designed to match the other Hitti chipsets and that's not uncommon. Um for manufacturers of specific stuff like that, 74hc 244 and that's about all she wrote. There's nothing really exciting on the other side of the board here. Geez, this.

um. Tato microscope handles I mean that board has angled it. You know, 30 or something like that handles that really, really nicely so you can see that whole board there. That's that's.

just brilliant. The Optics on this are great. I Love it. But yeah, that's all she wrote.

The Via stitching is just Absol abolutely everywhere. Look, they've got a channel in here, which is the um, uh, main output here. so that's uh, that's coming from. That's we got ourselves a driver over here.

I Don't know, You know you'd have to decipher that. uh, that part there. but uh, yep. ve stitching everywhere.

And as we talked about the uh, gold plating on the edge here before, it doesn't matter. it's not like it's going to leak out. they've got that inside as well on the different layers, so you know it. It's just fine.

Oh, here we go. We actually have some silk screen to tell us what which connector is what? That's the tracking generator, local oscillator and that's the tracking generator reference input. There you go. And as is standard practice with all these RF shielded enclosures, you see them all in Spectrum analyzers and RF siggens and everything.

They've got the machined aluminium things with each individual building block. They you know each block. uh, circuit block. They actually machine out a little part so there's like there's no leakage and you see the gold plate that makes contact with it.

There's no leakage between uh modules and channels and things like that. Fantastic. These things aren't particularly cheap, but you know, like they don't make these in millions so they're not going to cast these. That's why you can see all the Machining marks in there.

they've just milled that out and I suspect the main Spectrum analyzer module here is going to come out as well. It's fantastic. I Love this! I Don't have to dick around with taking out the steel shazzy and then you know around with the nuts on the you know on the connectors and things like that as you have to do with lots of Scopes This is just beautiful. It's designed for ease of module, uh, replacement, ease of assembly and disassembly and servicing.

fantastic. but of course you might think he's of servicing. You got all these screws on here, you know, like you have to to get a tight seal on all of these. uh, like a lot of your high-end stuff will actually use an RF G gasket underneath there.

and uh, if you take out all the screws on the real bleeding edge high performance ones. uh then, and you disturb the gasket underneath, the pressure of the gasket, separating all the sections and everything else, then you might have to get the thing uh, re-calibration uh checked. So yeah, just to make sure you know because the real bleeding edge RF Stuff: It really matters. This is only like a 3.2 gig one.

so it's You know it's like baby stuff in terms of RF it's real RF gray beards will probably go. ah, it's practically DC So I've undone all the number ones here and uh, we should in theory. Oh no, oh, there's one more left here. Oh oops, sorry.

one more left there. we go Do okay. they should have labeled that number one as well. There we go.

I Think it's it's just going to pop out as a complete module complete with there we go. The in connector got caught but uh, because it's got the you know it's got the extra thread sticking out there. but look, it's just one complete block. Beautiful.

And once again, as I said, this is great for production testing and handling and assembly and things like that and you know you don't have to like if you had one like in the Ryolf for example. uh, your assembly yield like you know the bigger your board is, the uh, you know the greater risk you take with your PCB yield and just you know one part in here. for example that didn't Reflow solder properly. the whole thing uh can fail.

whereas this, they can test the assembly separately and things like that. So there's lots of uh production advantages and uh design R&D advantages to doing it a separate module like that. but that's just that's winner, winner chicken all over. I Don't have to take out the shazzy dick around with any of that stuff Beauty All right, here comes the big reveal.

last screw here and unless I've forgotten one probably laughing at me if I have Tada Oh A, we be mooned. That's the back of it and all the RF goodness. Once we'll see lots of distributed element filters once again today. Yep, there we go.

A beautiful look at that. So let's take a detailed look at the main board here. and uh, we're only going to be concerned with the top side here because if you have a look at the bottom side here, there's just nothing of interest there. It's just all, uh, passives, bypassing and some regulation.

maybe things like that. so nothing special at all. Now it might look Dawn in at first with all these distributed element fils, and everything else, but as we've seen before, you can see that's pretty much a mod block approach and I've done a handy little overlay here that will, uh, attempt to hopefully explain all the different functional blocks and the signal flow on the board. So let's get to it now.

of course I can't guarantee this is 100% accurate I likely may not. mistakes on here and if I have I'll Endeavor to uh correct them with overlays. So let's start by taking a look at the RF input in the top left corner. This section here, of course contains a 50 ohm input impedance but that uh, little So 23 six package.

you'll see four of these here. These are actually uh, single pole double throw switches so they can actually switch in the Uh 50 Ohm load and various other stuff. So we'll go to a higher res photo for this and then zoom in on the RF section here and we can see that uh, the input is AC coupled there through C10 and then that goes into U1 which is a 955c as all the other ones here the So 236 Parts there some form of single pole double throw switch which which I can't find the data sheet for if I can I'll link it in down below, but you can see that uh, one side of the switch there I believe pin one there. um switches in Um C9 and R1 which is the Uh 50 Ohm load there so it's not a permanent 50 ohm load input and you'll notice that there's actually four dodes unpopulated there.

so there's a distinct lack of input protection here. So unless uh, there's something inside that little wimpy U1 switch there. um, there's you know, not much here at all. There's basically Al nothing.

On the other side, there is a tiny little diode D7 there, but jeez, it's wimpy. And if we scroll down here, we got a couple of more of these switches here And there's some Diod Four Dodes there. so I'm not exactly sure what's uh, doing there, but that looks like some uh, power supply clamping protection there. At least they start to have something now and a bit further down here, you can see that uh VR1 there.

it's got 20 written on it I'm going to assume that's a 20 DB uh attenuator there and you can see that's basically switching in uh, C16, that, uh, that straight controlled impedance line there. so it's basically either going straight. it's selecting either straight through or a 20db attenuator here. Next up, we go down into a HMC Once again Hit heght.

They're everywhere. They've got the entire solution for this thing, the HMC 307 and this is the digital attenuator. So when you go into the Spectrum analyzer and you set the input attenuation, you can set it in 1 DB steps. Um, up to Uh 31 DB over and above the 20 DB input attenuator.

And that's exactly what this chip does. So the software is limited by the capabilities of this chip. but yeah, nice device. DC to 4 gig, DC to Daylight and I Really like the way the designers have laid out this chip.

Look at this. there's the input pin and then there's the two ground pins right there so you can see all that via stitching to separate the input and the output so there's no uh coupling there. and then the pin below. that is the output.

So from a layout point of view, it allows you to lay it out with a minimum amount of coupling. Nice. But we're not done with our input section yet. If we scroll down a little bit more, we'll see uh, the signal flow down into our next section, which is of course, the preamp.

This thing has I Believe it's a a 10db uh preamp gain on it. Once again selectable, so we expect to see the digital switches there. and that's exactly what we get. So I can either bypass the Uh preamp or switch in the preamp.

But of course in this case you'll notice that the switches are bigger, They're a different package and we can actually get the data sheet. Surprise surprise. It's another hitte uh part. The single pole double throw.

Uh, it's a non-reflective switch up Dc2 not quite daylight this time. 3.5 gig. Uh, it's a non-reflective switch. You can see the internal diagram there.

It's actually got internal 50 ohm uh termination resistors in there. but uh, basically it's just a switch. It allows us so they use a combination of two of them. You can switch in your preamp or switch it out easy.

Now that's all bread and butter stuff. But look at all these other blocks in here and this is the complex operation of a spectrum analyzer. Not all Spectrum analyzers operate the same uh, but they use very similar uh techniques. So what we're going to do is take a look at a basic Uh block diagram here.

So we've looked at basically just one block here, the RF input attenuator in near the signal input there, and that includes the switching and the preamp and everything else. Now we expect to see a low pass filter in here, and that's what we'll see in a second, and then that goes into a mixer, which then Uh uses a localoc, mixes the two signals together, generates a higher frequency called the intermediate frequency, and then we expect to see a gain stage there. There's that gray Uh amplifier block there. uh, attenuator.

We won't see this in this one, but it doesn't matter. Um, that if then goes into an If filter, we'll definitely see that and then goes into a log amp and envelope detector, video filter, and display. But that's not quite how this one works. We need to look at another block diagram for that.

And as it says here, most Spectrum analyzers use two or four mixing steps to reach the final intermediate Uh frequency that we can then uh, in this case, or do all digital processing and actually display that because this is an all digital If system instead of a traditional Uh analog Spectrum analyzer. Anyway, so there's we're going to see several steps here. By the way, these Di Prrams come from the key site Application note: a150 I'll link it in down below. Highly recommend.

It's one of the best reads on uh how Spectrum analyzers work and everything else, so we expect to see uh in. Well, in this case, what we're going to see is two local oscillators. The first one goes into the first mixer uh and then the second one that goes into the second mixer. Here, if we take a look at the first mixer on the left hand side, there, that's the green circle with the X there.

We need this because we need to generate a higher frequency than our Uh frequency range of interest. In this case, our Spectrum analyzer can go up to 3.2 gig. so we have to generate an intermediate frequency higher than that because if we don't do that, then there will be uh dead bands within the measurement window that just won't work. So we have to actually mix that with a high mix our input frequency with a higher frequency to generate and intermediate frequency above our maximum 3.2 gig input range.

And if we go back to our original block diagram here, what we expect after our input stuff is a low pass filter and then a mixer with a local oscillator feeding into that mixer. Do we get that? Well, let's take a look. Yes, of course we do. You can see the preamp there on the left that we looked at before it then feeds into a down into that low pass filter which is again a distributed element Uh filter there with the various L's and C's and then that goes into a mixer IC there which then accepts the signal from above it there from that uh, nice looking uh bow tie distributed element low pass filter and that will come from the local oscillator as we'll see, but it's a bit more complex.

It's not like the local oscillator feeds straight in. we're doing some tricks with our local oscillator in this particular case, but anyway, the output from the mixer then goes into that Uh amplifier gain stage as we saw on the block diagram. and if we take a look at a high-res photo of the mixer and that Uh amplifi, fire if amplifier stage. Once again, we've got two Hite Parts yet again, the HMC 48 mixer there on the left and the HMC 716 Uh amplifier.

Let's take a look at the data sheets and this mixer can go from 4 to 7 Gig which is exactly what we want. It's above our operational frequency range of our amplifier and if we have a look at uh, the specs here, then our intermediate Uh frequency range DC to 2.5 gig and then our If amplifier chip the HMC 716. It's exactly what you expect. It's A in this case it's an 18 DB gain Uh amplifier, but it's got uh, the bandwidth of 3.1 to 3.9 gig.

So it's designed to operate within that range which is above basically our 3.2 gig maximum operational frequency range. and that's where our IF frequency is going to sit somewhere above 3.2 gig the exact value. Uh, we don't actually know unless we do more investigation or some measurements, but before we follow that intermediate frequency out, we want to see our local oscillator cuz I said before, it wasn't as simple as just the local oscillator feeding into the mixer as it shows on the Block diagrams for spectrum analyzers. So if we zoom in here, we can find our first local oscillator, our main voltage controlled oscillator and this one uses a Zedcom part there for the Vco, the voltage controlled oscillator and which is the big metal can there and another hitte PLL there to form our local oscillator.

Now this is made by a company called Zed Communications and they make a ton of different variants of these with different ranges and things like that and this one is going to cover the frequency range that we need. If you have a look at the Uh tuning voltage here, it goes from 1,800 to 4200 MHz or uh, 1.8 to 4.2 gig and pretty much exactly the range we need here. And this is our sweep generator we saw in the block diagram on the bottom left there the red sweep generator feeds into the local oscillator and then feeds into the mixer. But as I said, there's a few more steps after our local oscillator before we get to the mixer in this particular analyzer.

But as part of that local oscillator, we've got a Hite HMC 703 uh fractional synthesizer which forms part of the ultimate Uh PLL Local Oscillator Loop And we can see that here. if we take a look at the Uh demo board, you can actually get for this chip. It shows that there's a Vco integrated as part of the system here, in this case, a Hite HMC 508. But but in the case of the Sant Spectrum analyzer here, we're using a Vco from Zed Communications.

And if you believe the sales blur here, check it out. This platform has the best phase, noise, and spirous performance in the industry. Yes, thank you very much. But once again, you know the decent choices being made here to enable a pretty decent performance at a low price point.

Well done signant. But even with all that magic, the output of the first main local oscillator here is not high enough in frequency, so it goes into to a frequency doubler there. and uh, this is designed for two 2 to 4 gig input, so doubles that anywhere from 4 up to 8 gig. But once again, the exact bandwidth uh, frequency range we're talking about here we don't exactly know unless we did further investigations or measurement and the frequency doubler being used again a Hite HMC 189 here 2 to 4 gig input as I said.

so 4 to 8 gig output. Eh, it's designed for exactly this job and this particular part isn't obsolete. unlike uh, if you were very keen, you would have noticed uh o' plasting over the data sheets for a couple of chips before We would have seen that they're actually obsolete. So yeah, why are they still using them? I Don't know.

Maybe there's nothing better at the price point, but we're not done yet. No sir. Bob The output of the frequency doubler here for our local oscillator Uh goes into Uh two single pole double throw switches which then can select one of three band pass field. in this case, uh.

This particular Uh physical arrangement, the distributed element filter is called an interdigital uh band pass filter and so three different frequencies. You can actually see that there different Uh geometries there which actually selects the bandwidth and the response. And then there's three Uh single pole double throw switches on the other side. So the software can select one of three band pass filters on our local oscillator and these switches are different to what we've seen before.

These are Vwa 2- 63, blah blah blah blah blah. and these are high isolation absorptive. Uh. single pole double throw switches with integrated seamos, drivers and all sorts of weird and wonderful stuff.

And we don't care about the quiescent current really. Um, and 500 uh to six? 500 Meg to 6 gig uh. bandwidth. Pretty decent and we're almost there.

I've mentioned this before. you can see the output of that um one that selectable band pass filter there. then uh goes through just a little bit more stuff there and goes through another bow tie low pass filter. It's called a bow tie low pass filter because it looks like a bow tie.

That's where it gets its uh name from another low pass filter. Um, just takes the edge off something or other and then that finally goes into the mixer. So that block diagram we saw before and you see for all Spectrum Analyzers: the local oscillator goes straight into the mixer. Well, as you've seen, it's a bit more complicated than that for Ious performance reasons.

but if you're Keen Eye you would have noticed something in between there the output uh from the inter digital filter after the Uh switching and probably some little buffering there or something. uh then goes into this Odl looking uh Arrangement here on the board which is coupling um the signal to go over. If you follow the trace on the other side, it's coupling over to go up to the tracking generator local oscillator SMA connector and that jumps on over to the Uh tracking generator module we saw before so finally out of our mixer and then through our If gain stage which we've looked at uh, we expect to find an If filter and well, you bet you look at the output of the amp the 18db if amplifier down here Bingo it goes into another band pass filter, another interdigital uh type. once again, different geometry in there, uh to give you a different uh range and uh response of the thing and then that's followed by another cute looking bow tie low pass filter as well.

Once again just to take the upper edge off something. And if you're curious about how these interdigital uh band pass filters actually work when you can clearly see that both uh, like the input signal comes in and then it basically goes down to ground with a trace sticking up and then the other. Then the trace on the right hand side next to that uh goes up to ground at the top side and then the next one goes down to uh, ground. So how does this actually work? Well, it's because we're at high frequencies here.

These work at, you know, several hundred megahertz, up to you know, several gigahertz or something like that. They're basically are coupled resonators, but they're also known as interdigitated coupled resonators. So yeah, they resonate between the two and then it propagates along and resonates. And that's why you might see different spacing in there is to give a different pass band characteristic for this thing.

anyway. you you have to get into real complex RF Micr Strip type Theory to you know, figure out exactly how this works and there's a ton of math into it. and I'm sure you could Google it if you're really interested. but yeah, even though it goes down the ground, there, it gets through.

But we said here before that uh, this particular Spectrum analyzer Arrangement uses Uh two mixin uh techniques and so we need to find that second mixer and the second local oscillator as well. And if we pan across here Bingo the output of our filter there goes into another mixer uh, the 4 48 Exactly as we had before, but just like on the block diagram here, you'll notice that the output of the second mixer is a much lower frequency. It's within way under way within uh, the pass band of our Spectrum analyzer in this block diagram 322 MHz But in the case of uh, this particular one here, it's actually at 810 MHz And the we know that is because hey, look, we can look at the Um filters on the output of the mixer and we can see that there are saw filters or Surface acoustic wave filters and we can have a look at the data sheet for this particular Uh one. They're available in all different frequencies.

This one happens to be an 810 MHz sore filter so we know that's the output uh frequency of the second mixer. but this isn't low enough uh frequency for now us to do digital if sampling on. So what we want to do is feed it into another third mixer. just like what's showing here to actually downon convert it to a frequency that we a baseband frequency that we can actually sample with like a Joob blogs.

Uh, you know, 16bit analog to digital converter. And we can see that here. The output of the sore filter goes into this little white block here, which is a mini circuits. Yes We finally get a mini circuits Win in the design Here, it's not all Hite mini circuits.

one of the biggest providers of uh, these sorts of Uh mixers. And so this will go in and we can take a look at the data sheet for this minicircuits mixer as well. But there's nothing terribly exciting to see here. It's just a you know, basically 5 MHz to 1 gig mixer designed for this sort of uh application.

uh, down conversion. Uh, to a baseband signal. But wait, we're not finished with the mixer. Every mixer's got to have a local oscillator input.

Where is that coming from? Well, it, it is coming coming from the second local oscillator. but we need a much lower frequency. so you'll notice that the second local oscillator here as like feeding the second mixer across to the left. There, it also goes up and that same signal feeds a is divided by four and then that gets fed into the third mixer which does the down conversion.

So we've got our final RF frequency bandwidth here and this goes into H Curiously, a single pole for throw switch and that's what the IC is. so I'm not exactly sure what it's selecting there. you know there's some sort of different uh filtering options that it's doing there I'm not exactly sure what. Anyway, that then goes over into another single pole forrow switch here, which has only half the stuff populated, so that's quite unusual.

Why did they leave that out now as a user by the name of uh goou? if I'm pronouncing that correctly on the Eev blog? Forum Uh postulated for this one? Um, it it. I It certainly looks like another band pass filter in there. uh, with the inductors and the caps in there. and uh, that would be one of going into, presumably one of the channels of U85 on the left hand side there, the Uh single pole, four throw switch, and presumably there would be a software option for this to have another additional band pass filter on the final if before it, uh, goes into the sampler.

So maybe there's even a secret menu option for it if you could hack the firmware or whatever. Or maybe you know they had an early version of firmware that decided they didn't want it I don't know, could still be there? who knows. could be interesting, but yeah, I don't know if you could find it. You might be able to hack in your own uh ban pass filter in there for some additional functionality.

And the good thing about an experimental hack like that is that you're not really, you know, damaging anything. You're populating existing Footprints in there with an existing digital switch that's only affected if you enable a software option in the firmware to actually flick that switch and in, you know, put that uh filter in series with the final if there so you know you can play around with your heart's content. Without Really risking uh, damaging anything. So that's it.

We're finally through our complete block diagram here, but this envelope detector? We don't have that cuz as I said before, this uh, Spectrum analyzer uses what's called an all digital If filter so it does everything. after the If stage, the intermediate frequency stage, it just samples that directly with a high resolution uh High sample rate analog to digital converter and then does everything in software as we see in this key site application. Note here here is how uh, the key site X Series signal analyzers do uh and All Digital if they've got an ADC in there with the gain and the Alias filter, everything else but it goes into then a customiz see which in this case would be that Spartan 6 Fpga we saw is doing a hbit transform and then doing some filtering and then it can do the video bandwidth in there and does logs and powers and all sorts of and uh, the detector. all sorts of stuff all with inside.

uh, that' be happening inside that Spartan 6 Fpga no doubt. And then that goes into the pro and probably it'll be doing the Fft in there as well. Um, and then that just goes out to the display applications processor, which we saw earlier. So now we have to go full circle.

Right back to the main PCB under that block where we found our main reference oscillator before. And what do we find? Surprise, Surprise. An ADC driver designed specifically for if baseband processing. In this case, it's the Uh National semiconductor.

None of this. Texas Instruments Rubbish. Lmh 6517 It's it's designed exactly for this for a 16bit ADC And there's the block diagram down the bottom, so no surprises to find what's down below this. I'll give you one guess and congratulations you Winner Brass Razu.

It's an analog to digital converter. It's The Analog Devices Uh, Ad 9235 actually 12bit Surprise. Surprise, not the 16bit rubbish. I guess for Sigin, no 12bit will do the job just fine.

And uh, yeah, it's designed for ultrasound equipment. Oh, low cost digital oscilloscopes. There we go. Winner winner chicken dinner.

And you'll notice that we've got the- 40 part there. Uh, which means 40 Meg samples per second. This part's available from 20 up to 65 Meg samples per second. So 40 Meg samples per second.

We know that our If baseband frequency has to be somewhere below 20 cuz you know all that Nikist stuff. Really annoying. Yeah, so it's got to be at most half of that sample rate. So there you go.

That's a rather lengthy look inside. the brand spanking new sigin SSA 3021 Spectrum Analyz I hope you enjoyed that I Sort of went to town a bit actually going through the various sections on here I hope you found that uh, rather interesting. And as always, if you want to discuss this, jump on over the EV blog Forum links down below. That's where everyone's trying to going to try and discuss the pros and cons of this thing.

But hey, I could not fault this. There's no bodges in the thing. there's no crap Quality Parts in the thing. and they've designed and engineered the RF part of it really really well.

So the design and Engineering that went into the RF section which is, uh, much more capable and more complicated than the uh Ryo one they've really I think they've gone to town on it and siglin should be. Uh, pretty proud about this effort for their first ever uh Spectrum analyzer. So well done Sigin! Big thumbs up there so if you liked it, please give it a big thumbs up and links down below all that sort of jazz as always. Catch you next time.

Oh sorry I'm trying to rush to get this video out. It's been kicking my backside and I don't have time today to put it back together I Got to quickly finish this edit and get out of here. So yeah, trust me, it'll work. She'll be right.

No worries. Hi Welcome to T down Tuesday with another Spectrum analyzer The Ryol DSA 815 TG with the optional tracking generator Thought we'd crack it open. Take a look inside because Spectrum analyzers are usually a bit more interesting than other bits of test gear like your run-of-the-mill scope or your multimeter or whatever bit more engineering poured in these things. So you know what we say here on the E blog: Don't turn it on.

Take it apart.