Hi Welcome to the Eev blog an Electronics Engineering Video Blog of interest to anyone involved in electronics design. I'm your host Dave Jones Hi Why do I have the lab code on today? Well, it's mythbusting time. Okay, not so much a myth really. because this comes from a real problem that I saw on the Eev blog.

Forum Now it started. Uh, one of the Evev blog members, uh, Twistex. He actually reported that his Fluke 875 multimeter started playing up um, when it was near his uh wireless router and well, okay, you know, nothing unusual there. You know meters and all sorts of equipment are susceptible to electromagnetic interference.

In fact, the Fluke 875 is rated to keep its accuracy uh, up to around 3 Vols per meter now. I'm not sure what a wireless router actually puts out I Haven't done my research on this, but you know you know you can expect. Okay, it plays up. but another user Kiros he actually uh decided to get his mobile phone.

got his mobile phone and he put it next to his Fluke 875 and it killed it. It bricked it. so yeah, I thought I'd sacrifice my 875 and try it out cuz this is really interesting. Let's see what happens.

Okay, first up, let's try the router. I've got a dink uh wireless router here. it's a Dur 300 pretty standard sort of router. I've set it to 100% uh output uh, transmit power and as you can see, it's wireless.

I'm actually streaming a YouTube uh video here on my notebook so it's all transmitting. I've got a Uh Fluke 87 5 as you can see and let's put it near the antenna and see what happens. Yeah, it's certainly going up jumping up the 33 M AC but it's certainly not doing anything unusual. Um, I'll zoom in on that and um, see if you can see it.

And yeah, it's not doing anything. You know there's no weird stuff happening at all. So uh, yeah, no problem whatsoever. Test passed.

Okay, I know what you thinking? I didn't have the probes attached, so Taada I got the probes attached. Here we go. Yeah, it's much higher now. 300 MTS AC I Mean you know that that figure is just meaningless.

It's just picking up anything. but it's certainly not doing anything unusual. Um, at all. It's not causing any, uh, damage to the meter.

No weird digits as was, uh, as was reported. So there you go. No problems. Now, just before we try the mobile phone I thought I'd Uh, try just a standard cordless phone.

It's a Doro Um, don't know the model but doesn't matter. Let's put it about a foot away, shall we? and I'm going to call it and it's answering. It's transmitting. Okay, it's transmitting and uh, it should.

I'm definitely got my mobile phone about a meter away. Um, and there we go. Uh, no problems at all on the no problems at all with the fluke. You know it's it's picking up something, but it's certainly not killing it or doing anything unusual.

So um, a cordless phone? Perfectly fine. And for the big test, a mobile phone. this is a Nokia uh E71 as you see and it is, um not 3G at the moment cuz I get uh 3G coverage here. but okay.

I'm going to put it about a foot away and I'm going to ring it. Let's try it and see what happens. Okay, we're answering and we're talking. So the mobile phone is active as you can see.

um I'm getting. uh, you know I'm I'm getting full bars on there. but um, as you can can see, it's not 3G Okay, it's just standard. uh GSM but it's actually we're in the middle of a call so let's put it near it.

Wa yes, something's happening here folks. something's happening. Watch. see if I can, let's see if we can get this.

Oh yeah, Oh yeah. look something's going on. See that on the display I'm definitely recording this. Whoa.

look at that. look at that. So it has to get looks like it has to get reasonably close. Looks like it's got to get within say 6 in before it before it starts to do something and whoa yeah, it's completely neutering it.

Look at that. There it is. there. it is confirmed.

It does screw up. But it's not brick in it. It's not bricking it. it's it's fully recovering.

Whoa. Yeah, it's really really doing some weird stuff all right. But yeah, it seems the it doesn't seem to do anything on the right hand side, here. on the top, nothing but on the left hand side here.

Definitely look at that. Wow. Check it out. Awesome.

Yeah, there's something there's something that's susceptible that causes susceptibility on that left hand side. Um, in fact, let's leave it in the middle of the call. Okay, we're still on the call and let's switch it on, shall we? No, it just just really screws up the display and that's about it. Okay, I've just got a small collection of meters here.

the Cheap Vit BK Precision Xtech German Goss and Metro and The Fluke 87 and as you can see, we're still uh calling here. It's exactly the same call. I Haven't um, changed it? It's not. uh 3G it's just standard GSM and let's put them near these other meters.

No problems on the VY at all. Let's try the Xtec. No problems on the Xtec? No none. BK Precision.

none whatsoever. There's a yeah nothing gos and Metro get that on screen there? nothing on the gos and Metro at all. Not of a thing. perfect.

And our friend the Fluke 8 7 Tada look at that. Wow. Wow. that's really that's really something.

It doesn't happen at all. On the right hand side, not a thing, but left hand side within? Yeah, I don't know. a couple of inches. It's really starts to play up crazy, but we haven't pricked it.

so um, yeah, I guess um I don't know. I'm just, you know this either, hasn't you know? I'm uh, just different output power or something like that to the transmit Tower or something like that. But yeah, there's definitely a problem with the Fluke 87 with nearfield. um Em High Energy Em sources like that and let's just try another transmitter.

Source This is a little uh Uniden UHF uh walkie-talkie and let's put it right beside it. Let's put the antenna right there and um, see if we can do it. Here's the other receiving one and let's transmit. Check.

Check one two. No, it's just going up a bit, but it doesn't uh, doesn't do anything. I'm pressing the press to talk so it's definitely transmitting. As you can see, there's a little transmit uh, transmit symbol there on the display and nothing.

nothing at all. So that's okay. That's not not high enough at all. But the mobile phone there it is.

I'm still on the call. The mobile phone really waa hang on. Whoa. look look I killed it.

Look, it switched off the display totally Switched Off H Check it out. My my Call's been disconnected. Not sure why, but look, let's switch it off. No, it phew.

it looks like it's recovered. So yeah, B it you saw that it. It literally locked up the processor enough to not recover at all. Crazy.

Let's see if we can reproduce that. it's calling again Wa there. Oh there we go. Look straight up.

Switched Off Straight away That time. straight away. Yeah, it's come back. It hasn't killed the firmware like it did in Paul Curia Cos's fluke 87.

But as you can see, I can I can easily picture what happened to his happening to other people's because yeah, look, it switches the damn meter off. That's crazy. Okay, I've called it. We're taken out of the rubber holster and I got a loud speaker as well.

There we go. feedback and it's really, it's really killing the display. All of them are lit up. Whoa.

Upside down. Check it out. Wow. it really affects it, but we haven't bricked it.

There you go, and we're doing the same thing with the Gossen meter. Not a thing, no nothing, nothing. It's a great effect. I Love it.

But yeah, no. definitely the fluke. The fluke is bugged. Check it out.

Woohoo! Fantastic! Okay, let's try another phone. I Got a Nokia 6300 here not 3G but um I'm I'm on the call at the moment. it's actually transmitted as you can see and let's give this a try, shall we? Oh yeah, there we go. Oh yeah, boo yeah, look at that got him.

But it still recovers and let's just do one more a noia something or other I don't know the model but we're on the call, it's actually transmitting and let's give it a go. Hey there we go straight away. Boom! Gone Gone Ski and we couldn't leave it at that. I Had to drive around until I found 3G coverage to get out of the black hole I Live in so let's give it a go.

Okay I've gone outside I found 3G reception there it is 3G and uh, let's try it out. I'm transmitting. of course here it is Tada Oh look, check it out. 3G 3G doesn't do anything.

Wow, look at that so it looks like it's um, it's specific speically um, the GSM frequency. go figure. No, nothing. nothing at all.

3G doesn't do a thing and just as a control I've uh, turned off 3G So we've just got GSM now standard GSM as we had back in the lab and let's try it again. So let's just under control conditions. There it goes. Yep, there we go.

So it's definitely definitely the GSM frequency doing that. Yeah, what? Oh yeah, there it goes there. it goes, switched off and it just so happens. I Have the Fluke 875's uh, twin cousin, The Fluke 28 Series 2.

Let's give that a go, shall we? Once again? I've got the Uh I'm back on Gsm again. Okay, let's give it go. Go Here we go. Nothing.

The Fluke 282 doesn't do it, which is an identic. Well, you know it's an upgraded design, but it's essentially identical to the 875. Um, no problems at all. no nothing.

Not a thing. Not a thing at all. Whereas, if we bring in 875 again, here we go. There's a comparison.

There we go. Boop boop display just goes burco straight away. So the 875 is's definitely something to this. So there you have it.

It's not a myth. The fluke 875 is susceptible to nearfield. Em High Level Em radiation. particularly on this left hand side next to the LCD It's a real problem that fluke need to look into now.

I wasn't able to Brick Mine like, uh, Curios was and he lost his firmware and everything. Um, I wasn't able to do that I was certainly able to lock it up real easy with a GSM signal. who would have thought? and I didn't see any effect on any other the any of the other meters I had. So it's particular and including the fluke 28.

So that's particular to the fluke 875. There's a vulnerability there. fluke. Need to look into it.

And let's see if uh, fluke, live up to their uh, standby, their lifetime warranty and replace Curic Cos's unit. We'll find out. but don't try that at home with your fluke 887 kitties. Leave it to the professionals.

See you next time And if you are going to try this at home, remember kitties, wear protection.