rf absorbing material

[rich]

a friend of mine just sent me this link

http://shop.wireless-protection.org/blocsock---cell-phone-protection-28-c.asp

he bought one of the cell phone pouches and they also sent him a sample of the material, which he has lent to me. we tried wrapping the material around his zfr100/sta100, and the difference when running a scan on his lectro SRa's is spectacular, from 1/3 bar of rf without it (admittedly with the zfr very close to the antennas) to virtually none.

sadly none of the cellphone covers look as though they are big enough to cover zfr or trx900/sta combo, but you can buy the material in 1.5-2.6m wide, hopefully squares, though that bit seems a little unclear.

http://shop.wireless-protection.org/swiss-shield-products-24-c.asp

could be useful for those of use noticing rf spray from various things in the bag.

[Boomboom]

Interesting indeed for bag rigs with both Rxs and cam link Tx ...

[JDirckze]

G'day Rich,

As well as seeing the affect on the Lectro scan, did you do any tests on the performance of your Zaxcom system? I'm just wandering if this RF material will affect range or quality of the Zaxcom hop.

Cheers,

Jase

[Marc Wielage]

This looks like a cloth that acts as if it were Mu-Metal. Very strange... I'm skeptical of the health values, but it'd be interesting to take it and measure it and see if it gets rid of GSM roaming noise into analog connections.

--Marc W.

[r.paterson]

Hi rich

thanks for posting, i have ordered some material and will post back once i have done some tests, is it just me or does anyone else think manufacturer's should be looking at this type of solution rather than leaving it to everyone in the field to try and find solutions to a problem from a manufacture's product.

Richard

[rich]

Hi Richard.

I agree with you. But in the meantime, I can go out and get some of this material and do a bunch of unscientific tests and observe the results and not have to test it in a bunch of different scenarios or do safety testing etc etc

I did a similar test with my trx900/sta150 next to my qrx as I will be using it on my next job and again I saw a reduction in the rf noise seen by the qrx as well. When I get to the hotel I'll have some time to find the best way to cover it.

[Jim Gilchrist]

I have some experience with RF blocking fabric. I purchased 2 pieces of a fabric called Naptex to use while shooting onboard the carrier Enterprise for the Air and Space Museum in 1990 or 2000. We needed to film sync sound in places with reasonably high levels of RF/EMF. The material worked pretty well, removing all traces of the sweep of the flight control radar from a Nagra IVs-TC with no mic attached. We ended up using a dynamic mic on a short pole with a loop of cable at the recorder end when shooting up in the flight control tower, very near the flight control radar dish. I brought 2 IVs-TCs and 2 HHB DAT recorders along, the HHBs were useful below the flight deck, but plagued with radar leaks up on the tower no matter what I did. The material is Nomex woven over a steel wire base and is flexible. It's used to make protective suits for the techs that work on radio towers and what I bought were panels used to make a screened area for breaks and meals up on the tower. The material is very expensive, I'll look in my records for the cost in 1999.

In 2010 I was also aboard a guided missile cruiser undergoing final sea trials after a year in the yard for a complete refit. The Navy techs shot tons of stills and video and had tons of different RF protection options, including a material that felt a lot like paper towels that offered pretty hefty RF protection. Sadly, I can't find my notes from the job.

You might find something here. It's a web store that caters to folks that used to have to make do with lining their clothes with aluminum foil in the pre-Internet era. But there are legitimate RF/EMF protective materials available in the store that are hard to find elsewhere.

Best regards,

Jim

Note: Couldn't find a receipt for the Naptex fabric or a bookkeeping entry. Just moved, so lots of stuff in storage still, but the fabric was very pricey even back in 1999.

Edited July 11, 2011 by Jim Gilchrist

[Dan Ostroff]

Hello:

A newbie here but thought I'd chime in...

Another company that claims to have developed/invented their own material (seems similar to the one linked below) touting it as a fabric Faraday cage called Shieldsak (http://www.loksak.com/products/shieldsak).

After contacting the company they were able to provide some specs for the product:

Shielding effectiveness: Average 60db from 30Mhz to 1Ghz

I wonder if these will start to be incorporated into sound bags, pouches, etc.

a friend of mine just sent me this link

http://shop.wireless-protection.org/blocsock---cell-phone-protection-28-c.asp

he bought one of the cell phone pouches and they also sent him a sample of the material, which he has lent to me. we tried wrapping the material around his zfr100/sta100, and the difference when running a scan on his lectro SRa's is spectacular, from 1/3 bar of rf without it (admittedly with the zfr very close to the antennas) to virtually none.

sadly none of the cellphone covers look as though they are big enough to cover zfr or trx900/sta combo, but you can buy the material in 1.5-2.6m wide, hopefully squares, though that bit seems a little unclear.

http://shop.wireless-protection.org/swiss-shield-products-24-c.asp

could be useful for those of use noticing rf spray from various things in the bag.

[Audio Daddyo]

Here is some EMF Fashion ware I wore when working on a shoot about the Power Grid. With out this stainless steel suit and gloves when working on High Voltage power lines you would feel a continuous buzzing sensation around your body. I wore this suit at the end of the day when the linesmen let the crew go up on the 100' cherry picker and get a feel what it is like being next to 350 K Volts.

[johngooch]

You might find something here. It's a web store that caters to folks that used to have to make do with lining their clothes with aluminum foil in the pre-Internet era. But there are legitimate RF/EMF protective materials available in the store that are hard to find elsewhere.

Hey Jim, hope your well!

I tried a stainless steel mesh product from Lessemf.com. I used it to shield my RXs from stray rf coming from items in my bag. It did work, somewhat. Your mileage may vary but for me it worked and it stays in my kit. Cost me about 60$ for a small chunk.

john.

[JDirckze]

Just following up on this topic. Has anyone that has purchased some of this material done any tests?

I bit the bullet and ordered some material today, hoping to wrap my TRX900AA/STA150 and (fingers crossed!) solve some of the RF spray issues over my 411's. I'm hoping that there is no adverse affect to range of the Zaxcom hops.

Cheers,

Jase

[jason porter]

Jase,

I recently upgraded my RFs to 411's and all of a sudden, my Zaxcom is causing all kinds of buzzing and noise in my receivers.

What I did was add ferrite clip on beads to the power cables and run the receivers at line level. Noise is 99% gone. Maybe you are having the same problem?

[JDirckze]

Jase,

I recently upgraded my RFs to 411's and all of a sudden, my Zaxcom is causing all kinds of buzzing and noise in my receivers.

What I did was add ferrite clip on beads to the power cables and run the receivers at line level. Noise is 99% gone. Maybe you are having the same problem?

G'day Jason,

I followed that thread with interest, but I don't have noise as such, in the usual sense, but RF 'noise' across the frequency spectrum when I scan with my 411's.

Thanks for the thought though!

[Jack Norflus]

Just following up on this topic. Has anyone that has purchased some of this material done any tests?

I bit the bullet and ordered some material today, hoping to wrap my TRX900AA/STA150 and (fingers crossed!) solve some of the RF spray issues over my 411's. I'm hoping that there is no adverse affect to range of the Zaxcom hops.

Cheers,

Jase

Jase

Which material did you buy? Please keep us posted with your results.

[Marc Wielage]

I bit the bullet and ordered some material today, hoping to wrap my TRX900AA/STA150 and (fingers crossed!) solve some of the RF spray issues over my 411's. I'm hoping that there is no adverse affect to range of the Zaxcom hops.

The question I wonder is whether the spray is coming in through the body of the unit, or through the antenna itself (or through an input jack).

Me personally, I'm going to make a hood out of one and wear it over my head so that the voices from space aliens stop bothering me when I'm trying to take a nap.

--Marc W.

[JDirckze]

I ended up going with this stuff:

http://www.lessemf.com/fabric.html

And chose the Radio Screen product (I think). I'm not getting my hopes up, but if it helps it a little I'll be happy. I started off with a SRA5P in the bag and it was unusable, so I swapped out to 411's and it got better, then moved the 411's around in the bag and it got better still. If this material helps just a little, I'll be happy.

I'm pretty sure it was the remote antennae that was the main culprit of the RF spray... I'll do some more tests tonight and double check. I had some strips of copper tape installed in various 'key' places by the local Zaxcom guys, but those have since fallen off as I've been experimenting with using the Zaxcom as talent mics rather than hops.

Will keep you all updated.

[r.paterson]

hello

i have found the rf spray is coming from the sta150 and not the filtered nntena , please see attached pics one with the sta150 and filtered anntena and one without the sta150 but with filtered anntena, the rf material i tested around a marantz pmd620 and it eliminated 99% of the spray from it , my zaxcom kit is at zaxcom being checked out so will test the material when i get it back the sra receiver was block 24 and the trx900aa was block 26.

thanks

richard paterson

[r.paterson]

mmm only one pic apeared sorry

this is trx900aa without sta150 but with filtered anntena

i suspect the rf material will help get a scan like this hopefully.

thanks

richard

[TimPitot]

The best way is to move the entire zax tx out of the bag, forget the filter antenna, in my experience it made no difference whatsoever to my rx scans, my trx leaks rf regardless of where the antenna goes.

I had a loom made up do I can hang my trx900/sta100 with whip off a belt loop behind me. No worries since I started doing this.

[Derek H]

Just wanted to refresh this topic and see if any of you folks who bought the RF blocking fabric had any success. Thanks! -dh

[JDirckze]

Just wanted to refresh this topic and see if any of you folks who bought the RF blocking fabric had any success. Thanks! -dh

Waiting on my lovely Mother to sew a little pouch for me so I can sit the TRX900AA/STA150 in it...

I think though I may bite the bullet and do as Tim suggested, have a loom built and attach the thing around my back away from the bag.

[Ramsay]

Just wondering if anyone has tried wrapping the XLR connectors on jumper cables between the boom mics and butt plug transmitters to stop cel phone interference?

[Rob Beal]

I ordered one of the materials and it does seem to significantly reduce the RF spray from my Zaxcom ZFR100. It allows me to put my ZFR100 about 2" from my Lectro SRs.

I forget which exact material it is but I'll take a look when I get home and post the link.

-Rob

[Derek H]

Thanks rob

[Rob Beal]

Forgot to update this as promised.

The material I bought is called CobalTex and you can order it here (it's a big page, scroll down until you see CobalTex): http://www.lessemf.com/fabric.html

Here's what they say about it:

"This is a very unique multi-metallized fabric. Of course you get good far field RF shielding: 65-80 dB tested over 30MHz to 1GHz. But in addition, because of the Cobalt alloy top coating, this material offers remarkable radiofrequency magnetic shielding in difficult near field conditions. Great for reducing interference between tightly placed components. Light weight (only 100 g/m²) and very flexible, tight taffeta weave. Resistivity less than 0.1 Ohm/sq. 42 inch wide, silver colored. "

It does seem to actually work. I make it into a pocket that surrounds my Zaxcom ZFR100/STA150. My Lectro SRa's sit about 2" away from it and normally see a significant amount of RF gak when the ZFR100 is powered up. Here's a pic of a scan I just did on blocks 25 & 26 without any of the cobaltex in play (excuse the general filthiness of the bag... it's been on some very dirty projects recently!):

And here's a scan I performed with the ZFR100 nestled in its cobaltex pocket:

As you can see, a lot of broadband RF noise was eliminated or reduced.

Works for me!