Hi just another very quick uh, follow-up video from the previous one. If you haven't seen it, click here and uh, you'll be able to watch that where I adjusted this um Agilant frequency counter I've got that's just got its built-in um 5 PPM uh standard I adjusted the uh calibration pot on the back there to match my uh, Rubidium oscillator here and I did that with the frequency display on the front. but I just thought I'd show you another method and um, someone mentioned uh, you know, does you know having one of these uh, non conductive, non- metalic, um, adjustment things matter. Well, let's take a look at it.

What I've got here: I've got the scope set up uh channel one here that I'm triggering off. That is the 10 MHz reference output from my Rubidium oscillator which is also which I've also got going into the front of the frequency counter which we'll take a look at in a minute and and uh, then I've got the 10 MHz output here from the internal 5 PPM you know, crappy internal oscillator that's going into channel two there and we can see and I'm triggering off a channel one here. the Rubidium Oscillator. You can see that that's not bad at all.

This you can see the Uh 10 megaherz output from. Well, the 10 MHz oscillator inside the agilant Uh scope is not quite the same Uh frequency. If they were exactly the same, of course, they would be completely locked. This second wave form would not be moving at all and of course we can.

You know we can trigger off our channel two if we want and then the other one. uh, will move. It doesn't matter, but we're going to trigger off our Rubidium reference here and we're going to adjust this waveform and this is another way you can do it. I did it before using the frequency display on this, but this can actually be a better method.

It's more analog like. even though I'm using a digital scope, you can do it on an analog scope. Works exactly the same. So watch this now.

Um, I've already adjusted it so it was re. it's reasonably close. it's a as you can see it's scrolling past it, maybe a couple of Hertz and this is actually a way that we can directly see the difference between these now. um, what? I've got what I'll do first is I'll use uh, this screwdriver here and I'll put this into the pot and I near near the pot in there and I won't actually touch it.

So watch this. Whoa. look at that. Look at that.

it's going berserk and then I'll just touch the pot inside and it's gone completely. Haywire Look at that. but if I do the same thing with this uh non, uh, conductive, non-metallic um little adjustment pot, I can go near it and it will change a little bit. will change a little bit and if I touch it, it's not nearly as bad as the other ones.

So there you go, That is why you use these because what the pot in there is not a uh resistive pot. it's an adjustable capacitor and even with this s plastic it's act acting as a dialectric. Even though you don't touch it and you get very close to it that air, you're going to have the dialectric of the air, then the dialectric mater of the material and then your hand. Etc So you do actually change it a little bit just by going near it.

I'll try and get it more spot on so you can see that better in a second. and uh, but of course the metal one. um that is much much worse. That one just goes crazy.

So when you're adjusting these things, you're really do want one of these plastic adjustment pots. Now let me see if I can trim this pot in. Oh there we go. There we go.

Yes I do have my tongue at the right angle so that's not bad. Can I get it? no if I move it more in that direction now it's very touchy. Oh almost almost had it there. just out of pure luck it's uh, you're real.

It is a bit of luck depending on where The Sweet Spot of the that the plates in that capacitor need to be as to where you can physically put them but that's you know we're getting there. I have had it so it's very very close and you know that's not too bad. and that's a maybe about two Hertz out because if you follow the Peaks it maybe it's like two Herz So what we should see on this frequency counter. if we turn it around and have a look at the frequency, we should actually see that that frequency is about 2 HZ out there we go.

it's 2 Herz under because it's going in this direction. If it was going in that direction, then um, it would be 2 Hertz over. So there you go. you can actually you don't have to.

You don't need a display like this to actually, uh, see that. you can just adjust it using a scope like this. so if we make it go the other direction. oh oh look at that.

I've got it almost bang on. It's just the active touching it. my body extra capacitance in there is just making it go back in the other direction. So this is just another technique I Think it's a better technique for adjusting these sorts of oscillators because it's uh, you get direct visual feedback.

It's much better than just watching some digital display flip over cuz you really get a feel for it. But ah this is this is getting really tricky. Now if I take that off there we go. we maybe one htz see it's taking one oh no one.

Oh just under a Hertz So in the other direction so it should just be now showing over almost Htz on the display and there it is. Spot on. So that's just another way to adjust these pots. And of course, this thing will uh, drift with uh time as well.

because it's you know it's not a very. It's not an oven controlled oscillator, so when this thing warms up, you might find it'll slowly stop and maybe drift back in the other direction like that. given enough time. Like maybe if I blow on it? Perhaps No.

But certainly if I uh, bring some extra capacitance near there. What? You can get this reasonably spot on. I mean we're talking like a one one one Hertz is actually uh, 0.1 PPM So and that's why on these ones with the stock oscillators they put the uh calibration pot on the back because uh, well, cuz the oscillators are so crap that really, you know, before any critical operation, you probably should adjust it against the standard. really.

And well, if you're doing anything serious, you shouldn't have a uh internal oscillator if You' got a reference. And the silly thing there is, if you've got a Rubidium or a better oscillator to compare it against, well, you should be using that as the external input anyway. But anyway, there you go. That's just another method to do that.

And yes, these tools do actually make a difference, so hope you like that. Oh, almost 8 minutes. Worth so much for my quick video again. All right, here we go.

I Think it's going to reverse folks. I Think we're going to get it. We're going to get it. reversing.

There we go. Oh, it's spot on. Look, it's spot on and it's going to drift backwards. There you go.

That is the oscillator internal. It was bang on for a second there. Well, at one point it was absolutely precisely the same as the uh, Rubidium clock. And there we go.

it's drifting back. and if I put my THB even just putting my thumb over that hole, you can see that should I can make that go faster. Maybe just a little bit. You can kind of sort of see it.

So yeah, just any capacitive coupling near that thing at all. even half a bees dick there of capacitance. One 100th of a path for something is just enough to make that sort of drift a little bit. So yeah, stock oscillators hate them.

As you can see, there's uh, other oscillator options on this thing. You can get the uh, uh, I'm not sure I I Assume that the uh uh, us? uh yeah Ultra Stable Oven I guess is the best one. and there's a high stability oven. And then there's the I guess I don't know Ms medium stability oven I guess but uh yeah, this doesn't have it.

it's just got a regular, you know? SC cut crystal in there and eh. whatever. Hopeless and what do you know? this thing does have 12 digigit capability I Thought this model didn't. What I did was go in there and selected the Uh gate and set it permanently to the number of Uh digits like that instead of a regular gate time.

I Forced it to a number of digits and it actually goes up. Allows you to go up to Uh 15 actually, but it can't obviously. Uh. display 15.

Oh, there we go. Can't obviously display that many digits? It can only display 12, but uh, maybe internally. I don't know. Software wise, you could read it out.

perhaps, but certainly does display 12 digits I hope they're not dummy ones I assume not and I've actually done a video uh way way back on this and uh, drift of uh reference or oscillators crystal oscillators like this against uh GPS locked rubidium reference and how you can actually, uh, track the drift of this both positive and negative over time and then get data out of the thing. So if you want to, if you haven't seen that, it was many, many years ago and uh, you can do that by clicking right here. Tada The wonders of YouTube hyperlinking. Wow And yes, okay, if you want to get all funky, you can just switch your scope into XY mode and do the famous Listes pattern here and you can do it there we go.

Put my finger near it and I prefer the waveform like some people prefer. Um, some people prefer this. but I certainly don't. And you want to get a stable circle? circle there.

And the wobble rate, of course, is the same as the waveform drift rate. And there we go. we're almost bang on. So you basically want your perfect boy.

You want a stable circuit there and circle there that doesn't, uh, undulate. but nah, this thing's impossible to adjust. But Ultimately, I don't think that's you. Know it looks funkier, but it's not as useful as the waveform.

I like the waveform catch you next time.