DjGo Posted October 29, 2012 Report Share Posted October 29, 2012 Hello group, I did a search that came up with nothing, so I'd like to post this question. I found this company online selling EMF/RF shielding fabrics. http://www.lessemf.com/fabric.html What I would like to make is a pouch for my 788t to minimize it's RF-emissions into my Audio Ltd. 2040 receivers.. I allready took all other precautions like recorder on different power-source than receivers, connect receivers to the 788t's mini-xlrs instead of the standard xlr's.., increased the distance between the recorder and the receivers by screwing the CL8 on top leaving the 788t direct to the body and placing the receivers in the outer-front receiver-pouch in my soundbag. But I like to take this a step further by using Neutrik EMC-connectors, and RF-ferrite-chokes on all the cabling in the bag AND use some of that EMF-shielding fabrik. I wonder if anyone used it and could share the experiences..how effective is this fabric. On the manufacturers site it says the fabric can be grounded by using a simple clamp to a wall-outlet-3pin connector.. but then it's practicality will be reduced.. What about grounding this fabric? can I ground it to the power-supply in my soundbag to increase it's effectiveness? Is grounding needed at all? Thanks for any insights, kindest regards, Diego Quote Link to comment Share on other sites More sharing options...
JDirckze Posted October 29, 2012 Report Share Posted October 29, 2012 LessEMF Radioscreen and Zaxcom thread here: Quote Link to comment Share on other sites More sharing options...
DjGo Posted October 29, 2012 Author Report Share Posted October 29, 2012 LessEMF Radioscreen and Zaxcom thread here: Hey thanks Jason!! very helpful Quote Link to comment Share on other sites More sharing options...
Wandering Ear Posted October 29, 2012 Report Share Posted October 29, 2012 Dj, I use it with my nomad. I notice any difference, but don't expect the world to change. Larry has a great post in the above thread explaining how difficult it is to reduce rf emmissions Quote Link to comment Share on other sites More sharing options...
studiomprd Posted October 29, 2012 Report Share Posted October 29, 2012 " can I ground it to the power-supply in my soundbag" yes "to increase it's effectiveness? " maybe Quote Link to comment Share on other sites More sharing options...
LarryF Posted October 29, 2012 Report Share Posted October 29, 2012 Hi Diego, Here's the problem with grounding: At 600 MHz a quarter wavelength (antenna) is 5 inches. If the wire you use for grounding is a substantial part of 5 inches it will radiate very effectively and perhaps make the RF problem worse. If it is longer than 5 inches it will either radiate or do very little. You really can't win. I wish I could find an article I read years ago, but in the article the writer stated, "A ground can be capacitive, inductive or resistive. It can act like an antenna, a transmission line, or like nothing at all. It rarely acts like a ground." The best that you can do with a metal fabric pouch is enclose the offending unit completely in the pouch and ground (touch) the pouch to the case of the unit. This would might work well except you are going to have wires coming in and out of the pouch. Basically, you can try it but be prepared for probable disappointment. The most dependable solution is to get the receiver antennas away from the offending unit such as with a coax antenna. Inches do count. Best Regards, Larry Fisher Lectrosonics Quote Link to comment Share on other sites More sharing options...
Philip Perkins Posted October 29, 2012 Report Share Posted October 29, 2012 I have some of the RF fabric from Europe, used with a 744T in a very small bag w/ 411s. It helps (according to the 411 RF display), but it isn't perfect by any means. My 744 is powered by the onboard L-mount battery so there is no DC power cable to add to RF issues. philp Quote Link to comment Share on other sites More sharing options...
DjGo Posted October 30, 2012 Author Report Share Posted October 30, 2012 Thanks Larry, very helpful indeed! I don't expect miracles using the fabric, but I'm willing to try everything and experiment a bit. Thanks for explaining the grounding part.. Right now I am in Kyrgystan (radio-mic-paradise RF-wise) and I am getting astounding range by just placing my dipoles on a boom, away from the recorder. Quote Link to comment Share on other sites More sharing options...
LarryF Posted October 30, 2012 Report Share Posted October 30, 2012 Lectro needs to make some crossed dipole beanie hats with the antennas taking the place of the propeller. This would get the antennas properly away from the recorder and also gain a little altitude. We should be able to get that together by very early April. Best, Larry F Lectro Quote Link to comment Share on other sites More sharing options...
johnpaul215 Posted October 30, 2012 Report Share Posted October 30, 2012 Watch out for previous art when you apply for a patent. Quote Link to comment Share on other sites More sharing options...
greg sextro Posted October 30, 2012 Report Share Posted October 30, 2012 I created a pouch made of this fabric for a zax hop. Yes, I noticed less rf on my receivers, but what helped just as much/even more was relocating the zax hop tx to my shoulder and powering it with batteries, as opposed to my bag power. Quote Link to comment Share on other sites More sharing options...
LarryF Posted October 30, 2012 Report Share Posted October 30, 2012 I created a pouch made of this fabric for a zax hop. Yes, I noticed less rf on my receivers, but what helped just as much/even more was relocating the zax hop tx to my shoulder and powering it with batteries, as opposed to my bag power. Like they say in the real estate business, there's only three important things about real estate, "Separation, separation, separation" or something like that. Best, Larry F Lectro Quote Link to comment Share on other sites More sharing options...
VASI Posted February 9, 2013 Report Share Posted February 9, 2013 Also check here Quote Link to comment Share on other sites More sharing options...
sergiofucchi Posted March 6, 2013 Report Share Posted March 6, 2013 I do not think that's the 788T to emit radio frequencies that disturb your receivers. Also because the 788T has an external structure antimagnetic and for this reason it is quite heavy. I give an example. I keep my cell phone next to the recorder and if a call comes in while it is recording no interference is recorded. So if no radio frequency disturbance enters, it is not possibIe it can get out. Sergio. Quote Link to comment Share on other sites More sharing options...
soundslikejustin Posted March 6, 2013 Report Share Posted March 6, 2013 I do not think that's the 788T to emit radio frequencies that disturb your receivers. Also because the 788T has an external structure antimagnetic and for this reason it is quite heavy. I give an example. I keep my cell phone next to the recorder and if a call comes in while it is recording no interference is recorded. So if no radio frequency disturbance enters, it is not possibIe it can get out. Sergio. Accepting interference and not having an issue, an giving off interference are two VERY different things. Sound Devices themselves have admitted that the 7-series recorders give off RF in certain frequencies (as do all electronics) and have provided various solutions for users. Quote Link to comment Share on other sites More sharing options...
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