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Hacking a microwave detector

This message is really directed at Mr. Liebermann, but I'll ask it publically so anyone else can reply if they wish (and because it is bad form to email someone out of the blue using an address you obtain off a newsgroup).

I was reading thru some old posts on this newgroup, and I came across one that Jeff Liebermann posted about some tools that may be helpful in debugging wireless networks. One of them was a Microwave Leak Dectector sold by Comfort House.

He implied that he hacked one to add an antenna to it to better pick up microwave leakage. But the pics he had a link to didn't have a pic of the actual hack, nor any directions on how to do the hack.

So I went on over to the dealer linked, and took a look at the device in question. Low and behold, I already own it! A little over a month ago, I worked on a project that I was supposed to go to various people's homes and see how much of a leak the average microwave had. The client supplied me with the same model (near as I can figure from the pics on the dealers web site, I don't actually know where mine was purchased, it was just sent to me to use and the client didn't want it back when I was done).

I have no idea how well it works, it is the only one I've ever used, but in my testing, it only seemed to have a range of a few inches from the microwave. But I was also surprised to find that very few microwaves leaked (I tested about 75, and only 2 ever set off its alarm, most registered nothing, or very low values)... so it is possible this one just doesn't work correctly. It doesn't detect my WAP at all (Linksys WRT54G), and I keep forgetting to test it against my laptop (which has once again been left at work so I can't test it right now).

So I'm curious if Mr. Liebermann would be kind enough to write up a quick and dirty set of directions to hack it (you know, what kind of antenna to use, where do I solder it to the logic board, do I need to remove anything or jumper anything, or whatever... I know my way around the basic tools, although I have no experience or access to an oscilloscope, so if one is needed, I'm SOL). I was going to guess that you remove whatever is missing in the first pic, and attach the antenna there... but I opened mine to find that whatever is missing, is missing on mine. So then I wasn't sure if that first pic was supposed to show the available antenna connection points, or if it was just a close up of the board. I'd be happy to just slap an antenna on there, but I figured I'd ask first, just in case doing so really opens a portal to the 3rd plane of hell (which is fine too, but I want to know if I should be prepared to do some demon bashing)

Of course, this assumes I have the correct model unit. I think the original post was from some time in 2004, and the unit I have is stamped with Feb 15 2005, so it may be a different or revised model. The info says it an MD-2000 Digital Readout Microwave Leakage Detector. And the guts of it look the same as his 2nd pic (or at least in all the important ways, mine has a few more numbers stenciled on it, but all the parts appear to be the same).

So any directions, hints, or tips Mr. Lieberman (or anyone else) feels like tossing my way would be appreciated.

-chris

(standard spelling disclaimers apply until I can get a newsreader that offers spell check... not likely to happen any time soon)

Reply to
chris
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Yep. I try to answer questions in newsgroups and mailing list for free because everyone learns from the answers (even if they are wrong). I also kinda enjoy being helpful. However, if you want personal consulting, where only one person benfits from my efforts, be prepared to pay for my exhorbitant consulting rates.

Guilty as charged. Original photos, before I stuck on the dipole at: |

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diode detector is at the far left labelled "C2" on the chip and "D1" on the board. I thought I had a photo after I added the dipole. I guess not. Sorry.

Yep. It's not very sensitive. Even with an external dipole antenna, it would only detect my BEFW11S4v4 router up to about 6 inches. Without the antenna, it had to be right up next to the antenna to detect anything. Considering the power levels involved, I'm not suprised.

Incidentally, if you have a 2.4GHz cordless phone, try putting the handset inside the oven, close the door, and punch the "call" button on the base unit. The phone will probably beep. So much for microwave oven shielding.

Sure. The first problem is finding the detector. My fabulous carpentry abilities resulted in 6 bookshelves, 8ft long, all peeling off the wall, and dumping everything onto the floor and table. |

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was after I cleared off the shelves, brackets, and upper layer of books. One of my laptops was on the table and got rather bashed in. The detector is under there somewhere. I'm still cleaning up the mess.

Nothing exotic. Just two pieces of wire. I stuck a capacitor in series with each element to keep the DC off the antenna, but using insulated wire will work as well without the capacitors. I'll try to find the beast this weekend, make a few changes (i.e. start over) and post some photos. Bug me if I forget.

Reply to
Jeff Liebermann

Ditto, but not so much on newsgroups myself. I'm not sure why, but I just don't tend to post to newsgroups very often. In fact, this is my first run back at it in a few years (I used to participate in a FileMaker Pro group a long while back, I think I was still on dialup back then). But I do spend a good deal of time on mailing lists, and it always irks me when list members email me directly. For some reason, I feel like they are trying to get free consulting when they do that, yet if they ask the same question via the list, I chime in with an answer happily. Go figure.

Even right against the antenna I don't pick up anything. (tested it on my operating ch 11, as well as Ch 8 and Ch 9, didn't bother with any other channels after those three failed to be seen).

Hey, maybe I should stick a high gain parabolic dish on it and use it as my wifi tracker.... any idea how much play there is in the pickup spectrum? The unit says it is calibrated to 2450 MHz, since that sits between ch 8 and 9, will there be enough play to grab things from Ch 1 thru 11? Or is there a way to expand its spectrum?

I do... VTech, some early model of multi-handset to single base thing, I think it is still on the market, works REALLY well, doesn't bother my wireless, but totally screws up the old X-10 2.4 GHz cameras.

I'll have to see what happens when I put it in the microwave.

Lovely... looks about like my office after I trip over one of my piles of crap. Usually resulting in me spewing a number of obscenities, while my coworkers down the hall roll out a chorus of laughter (not a day passes that one of them doesn't comment on my death trap of an office... if they would stop breaking things, I'd have time to catch up on the work and clear out some of the mess!)

Thanks muchly!!!

-chris

Reply to
chris

Made for CATV. Promax MC-577 stops at 2150 MHz and doesn't cover

2.4GHz. Did you modify it in some way to use it? Downconverter perhaps?
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$1742 list.
Reply to
Jeff Liebermann

I guess for a once off its fine , truthfully though if finances permit take a look at a Promax MC-577 for a real toy :_) Had mine about 20 months and certainly earned its keep .

Reply to
atec

I tried this tonight. Looks like my microwave is properly shielded. The phone didn't respond to the page while the microwave door was closed. I opened it, and a moment later, the phone started chirping away like it should.

I've seen this experiment mentioned in other places, so I'm guessing either it is an "old wives tale" that people keep spreading without actually trying (from what I've read of your postings, I find it hard to believe you would be guity of that), or, my microwave is in the minority of proper ones.

Although, like I mentioned previously, when I did the microwave leak test at homes around the area, I was surprised at how few appeared to leak much in the way of anything. So maybe the cordless phone trick is a combo of the two... it naturally works for people with bad microwaves, but many others spread the info without having tried it themselves. (I try not to be that way if I have a choice, I like to try things out first hand... eventually I'll try hacking WEP just so I can see how easy or difficult it really is)

-chris

Reply to
chris

I take it the internal antenna is those two solder points next to it (ie: on the other side of the board)?

Lots of interest here, please keep us in mind!

Reply to
William P. N. Smith

I suspect that the antenna is the only tuned thing in the circuit, so it's pretty wide-band...

Reply to
William P. N. Smith

Yes its a little modded , although out of the box it does go 2.4 with reduced sensce , and its not a catv rather a sat box...

Reply to
atec

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