thanks

Andy

thanks

Andy

It's not that crazy when you consider that the magnetron inside it is putting out enough energy to literally melt your brain in the time it takes you to read Dilbert in the morning paper. That's an insane amount of power to be shielding with anything smaller than a bank vault, so for as light as it is, the shielding is pretty effective in my book. You are right that there are usually a few small leaks though, which is why I don't stick my face in the window to watch the turntable spin. My eyes are bad enough as it is without boiling the ocular fluid in them.

Even grounding can create noise in analog signal paths, if you accidentally get two ground references that aren't at the same relative potential. Yet another of the many reasons I love digital signal transmission so much.

I can't remember what I was getting at ~1 foot, but it was pretty high, so I suppose it'd have been around 13 dBm. I find it ironic how high up a microwave sits and how many guys stand just right in front of it! But yeah, your eyes are usually the first thing to hurt if you are starting to get cooked, but if you believe that RF may cause cancer, then its something to consider.

And you are right. If you have bad grounding on an analog line, you'll have noise. But this is a digital recorder with the mic disconnected right? The mic, if it were the quartz crystal or similar type would be your biggest sensitivity issue. Unless I'm missing something, which is very possible!

You are correct about the microwave. They aren't very good at blocking their own frequencies either. I don't remember a microwave that I've tested with a Spectrum Analyzer and Cal'd antenna that didn't leak 10 dBm at about 10 feet. That's crazy.

You should also keep whatever container you are using grounded. This would greatly help its EMIC.

It's not that crazy when you consider that the magnetron inside it is putting out enough energy to literally melt your brain in the time it takes you to read Dilbert in the morning paper. That's an insane amount of power to be shielding with anything smaller than a bank vault, so for as light as it is, the shielding is pretty effective in my book. You are right that there are usually a few small leaks though, which is why I don't stick my face in the window to watch the turntable spin. My eyes are bad enough as it is without boiling the ocular fluid in them.

Even grounding can create noise in analog signal paths, if you accidentally get two ground references that aren't at the same relative potential. Yet another of the many reasons I love digital signal transmission so much.

Oklahoma weather is starting to tick me off. It has stormed every night this week with torrential downpours. At this point I am praying for a quiet night tonight, because this is starting to get ridiculous. I have everything ready to go just sitting by the desk, lol. I dunno, usually in august Oklahoma is firmly stuck in a drought. Will try again tonight.

Andy

We had a rainy June, which has led to a hot and humid August. What we are finding is the quantity of EVP that we get is a bit influenced by weather, with more seemingly in turbulent weather conditions. So I do agree with the thought that inclement weather sometimes does activate para phenomena.

I hope you get the quiet night. Looking forward to seeing your results.

I'm curious to hear the results of your experiment Andy. Eric and I tried the microwave route with results such as yours. I also looked at the $15.00 Faraday cage, but honestly did not want to waste money if that doesn't work either. So please post results as you can.

Oklahoma weather is starting to tick me off. It has stormed every night this week with torrential downpours. At this point I am praying for a quiet night tonight, because this is starting to get ridiculous. I have everything ready to go just sitting by the desk, lol. I dunno, usually in august Oklahoma is firmly stuck in a drought. Will try again tonight.

Andy

AM/FM radio was placed in chamber to check attenuation of mediumwave and FM VHF signals

baby monitor 400mhz was placed in chamber to check attenuation of UHF lo signals

800mhz work radio (motorola trunking) was placed into chamber to check attenuation of UHF hi signals

80211g usb receiver was placed in chamber to check attenuation of 2.4ghz signals

That's pretty clever!

In all cases, the radio either lost signal or connection. I cannot be that accurate with the things that I have around the house, but I am pretty comfortable that this solution is broad enough to properly attenuate medium wave signals all the way up to microwave signals. Only wildcard would be longwave stuff, but longwave propagation tends to penetrate just about anything.

Well, the RF bands are filled with all kinds of stuff all over the place that those devices won't pick up. But let's be realistic, you are probably only interested in what is likely to interfere with the recorder. I don't really see RF for an audio recorder really interfering in any way, unless you have a bad ground and copper, or some similar good conductor creating an antenna effect. I think your paint can will certainly block out RF radiation within reason for the experiment though. That's my professional opinion anyway. I wouldn't sweat trying to measure any RF around the area and I have never placed much worth into actual Faraday Cages, except for ESD. RF can reasonably be blocked by simple methods.

baby monitor 400mhz was placed in chamber to check attenuation of UHF lo signals

800mhz work radio (motorola trunking) was placed into chamber to check attenuation of UHF hi signals

80211g usb receiver was placed in chamber to check attenuation of 2.4ghz signals

In all cases, the radio either lost signal or connection. I cannot be that accurate with the things that I have around the house, but I am pretty comfortable that this solution is broad enough to properly attenuate medium wave signals all the way up to microwave signals. Only wildcard would be longwave stuff, but longwave propagation tends to penetrate just about anything.

I have tried variations in the paint bucket faraday cage approach and honestly, they are too RF leaky. I have made sure that the lids are stripped of any coatings and are making good electrical contact with rest of the bucket. Just didn't like the amount of RF that was still making it's way into the chamber.

So did a little research and found some DIY solutions using basic kitchenware, lol. Basically I will be using a large covered pot and placing a sealed tin with the recorder inside it. Preliminary testing shows that this is a much better solution with RF blockage, and I think we have a winner. If I wasn't saving every cent I have at the moment, I would likely use the faraday cage from sciencefirst.com for 15 dollars.

The current RF shielded enclosure that I have come up with is more of a Hoffman box, but unlike a Hoffman box, I plan on grounding it in the same fashion as a faraday cage. First experimentation will likely begin tomorrow night.

Keep you updated

Andy

I've always hated that DVR stands for two things in this field. That's why I like seeing the spread of DAR (digital audio recorder) to stop the confusion.

Keep up with the experiments and let us know what everyone finds.