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Author Topic: Can RF erase CF cards?  (Read 787 times)
KQ6UP
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Posts: 136




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« on: May 20, 2007, 10:51:41 AM »

I am a professional photographer.  Yesterday I had a photo shoot where I had all of my CF cards with me (5 in all) in my camera bag.  When I took out my camera and turned it on I realized that I had photos from a previous shoot in the camera.  I removed this stick and replaced it with one from my CF wallet.  Strangely, the camera said no file system found for this new other chip (I had been hamming it up the whole way to the photo shoot HF 100 watts, VHF 50 watts, UHF 35 watts.  The camera bag was about 2 to 3 feet from the HF and the VHF/UHF antennas the whole time).  This chip was just recently formatted, so it should of had a file system.  I then formated the stick, and shot my scheduled shoot.  When I got home, the only images I found were the shots that were on the chip in the camera.  The other images from the previous shoots were gone.  I tried image rescue software, but the 2 newer high speeds card were blank even to the recovery software (I have never seen this before).  Usually, one can recover all of the old files even after they have been erased.  I have always been able to recover about 1G worth of files from any card I have recovered.

Has anyone had any experience like this?  Anybody have a clue to what happened?

Chris KQ6UP

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AA4PB
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« Reply #1 on: May 20, 2007, 07:03:26 PM »

I haven't experience it but it certainly is possible if you have enough RF. Normally when you erase a file it isn't really erased, it is just marked as erased in the directory so that it doesn't show up. That's why recovery software is able to recover the erased file. Once more space is needed the erased files begin to be overwritten and are no longer recoverable. In your case you say the formatting is gone. Once the file structure is gone the recovery software won't work.

It might be worthwhile to get a metal container to carry your CF cards in. I've actually done some testing with metal zero cases and find that with the lid locked down very little RF gets thru them, even at VHF and UHF frequencies.
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KC1NCR
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« Reply #2 on: May 21, 2007, 03:26:18 AM »

A short while ago I used a palm pilot fo work . When I had it in the work truck and used the vhf/uhf radio it would wipe the data out. There would be zero info left, just like you removed the batteries and reintalled them.I know it is not the same as your photo card but simular. I hope you had the pics. saved some where .    Jeff
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KQ6UP
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« Reply #3 on: May 21, 2007, 08:38:20 AM »

Unfortunatley, I killed a $300 dollar shoot. I also might of lost the photographer I was shooting for a anual gig with Kiaser Permanente.  This is REALLY bad, but they are GONE, DADY GONE.  No software recover succeeded the CF card was completely blank.

Chris KQ6UP
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KQ6UP
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« Reply #4 on: May 21, 2007, 01:27:16 PM »

I seem to get conflicting answers on the net.  I even called customer support and they told me they have heard of complaints with cards being damaged in environments that have extreme EMI.  However, none of these comments and other thigns are verry scientific and convincing.  It seems like no real studies have been done as to the threashold of EMI that will destroy data on the card.  This really stinks because I need to find out the source of the problem so that I can trust my gear again.

Chris KQ6UP
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AA4PB
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« Reply #5 on: May 21, 2007, 04:15:01 PM »

It should be easy enough to test. Put a card on the seat and key up the rigs - see if it erases. Put a card on the seat and wrap it in aluminum foil. Key the radios and see it it erases.

I doubt that there is any cumulative effect. Given the technology of the cards I would think that all it takes is for the RF voltage to reach some threshold level one time to erase the card. Since it happened to you twice it seems to be pretty repeatable.
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KQ6UP
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« Reply #6 on: May 21, 2007, 08:38:20 PM »

I tried it on 4 of the bands that I had operated on and the chips were fine.  I don't know what the heck.  Arrrghhh!!

Chris KQ6UP
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W3LK
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« Reply #7 on: May 24, 2007, 08:43:40 AM »

Anything is possible. I agree with the test suggestion.

Having said that, I have never had my Palm, my CF cards, my SD cards or anything else affected in any of my vehicles over the years - either from 100w of HF and 6m or 50w of 2m and 440.

If it IS happening to you, I am willing to bet you have an improper antenna installation (mag mount, glass mount or improperly grounded) and the feed line is radiating. I cannot imagine any other way for RF being radiated outside a metal vehicle affecting memory cards or a Palm inside the vehicle - not at typical amateur mobile power levels. Even a KW at home with a (temporarily) radiating feed line had no effect on the same items sitting four feet from the feed line.

Lon - W3LK
Baltimore, Maryland
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KQ6UP
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Posts: 136




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« Reply #8 on: May 24, 2007, 09:15:01 AM »

I have soft top jeep.  So RF would get in by that virtue.

Chris KQ6UP
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W3LK
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« Reply #9 on: May 25, 2007, 10:48:48 AM »

Chris:

Spent last evening trying to erase/corrupt a CF card. I  actually taped the card to the side of my HS-1800 HF antenna's coil - no effect at all running 100w on any HF band.

Same thing with my Larsen NMO270 - card up against the whip - nothing happend on either 2m or 440 with 50w.

With the adverse conditions many of the cards are successfully used in, it is very unlikely your radio erased the card. I have never seen any written warning about high RF levels. Also, my stuff regularly goes through airport screening with no problems.

One thought - are you formatting in the camera or in a card reader attached to your computer? I HAVE seen a few cases where a card was formatted on a computer and then the camera had trouble writing to the card.

73,

Lon - W3LK
Baltimore, Maryland
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W3LK
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« Reply #10 on: May 25, 2007, 11:03:17 AM »

Chris:

One further thought ...

What brand are the cards and where did you buy them? SanDisk cards purchased off of eBay have a 80 percent chance of being counterfit and potentially defective. The failure rates from some suppliers reportedly are exceeding 50 percent.

It was recently discovered that virtually every SanDisk card sold at a major office supplier over a six-month period were counterfit.

The failure rate with many of the no-name cards is very high, also. The risk is higest with the super large capacity cards. Unless I am shooting RAW, I never anything larger than 1Gb. Incidentally, everything I shoot now has SD cards.

I hope you have no further problems. I know that sick feeling when the files "disappear". Same feeling I had in the old days when I accidentally opened the back of the camera with film still in it! Smiley

73,

Lon - W3LK
Baltimore, Maryland
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KQ6UP
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Posts: 136




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« Reply #11 on: May 25, 2007, 11:36:00 AM »

I am using the highest grade Lexar media.  I did not have the problem with their 80X and 40X media.  Just the 300X media.  Also, I don't format on the computer.  I use the camera to format.

I would have guessed operator error, but the fact that there was absolutely nothing on the cards for the recovery software to find makes me very suspicious because, theoretically, recovery software should always find old images.  Unless it has been zero written or deep formated.

Chris KQ6UP
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KE4DRN
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« Reply #12 on: May 25, 2007, 02:30:15 PM »

hi,

perhaps static electricity
caused the loss of data ?

73 james
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W3LK
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« Reply #13 on: May 28, 2007, 10:39:06 AM »

<< Just the 300X media. Also, I don't format on the computer.>>

Unless you are machine-gunning photos and filling up the write-buffer, there is little need for the faster write speed of those cards. They DO d/l a little faster to the computer, but that's about it.

As for Lexar, they are about the same quality as SanDisk. No better; no worse.

73,

Lon - W3LK
Baltimore, Maryland
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