Um............ Yeah. Kinda thought the same thing...........
----- Original Message ----- From: "Tom DeReggi" <wirelessn...@rapiddsl.net> To: "WISPA General List" <wireless@wispa.org> Sent: Monday, April 26, 2010 5:34 PM Subject: Re: [WISPA] Ever wonder how bad RB333/444 stacked cards interfere? > I'm very interested in your reported data. Its nice to see the results > actually using a spectrum analyzer. > > Actually, we thought it was possibly advantageous to have the slots > stacked > because of the ease to fasten a isolation barrier between cards. And we > feared that cards side by side would equally get interference comming from > reflections from the metal case walls, trapped inside the case. > > What we did was take card stock cut to size and wrap it with aluminum > foil, > and then put that inside a static bag. We always mount the SBC with the > card > Slots at the top side of the case. We then slide the static bag inbetween > the two cards, and follow up with a peice of electrical tape. Even if the > electrical tape unsticks over time, the isolation barrier is resting in a > position where it would likely stay in place over time. > > We also are more selective on which cards we use in these stacked slots. > We > never use a dual antenna port card, unless both have a pigtail on it. > As well, prefer mmcx ports because they have better isolation than UFL. > Some > report that UFL actually has lower loss of its own signal than mmcx so UFL > preferred in systems with single cards. But when stacking cards, isolation > of mmcx may be more advantageous. > > Its also relevent to point out a large part of RF escape can be the > pigtail > itself, if not a high quality pigtail, so one should avoid having the > multiple pigtail paths interwine, when possible. > > It should also be noted that the locations in which RF is injected into an > adjacent circuit is not always as it seems. For example... If can be > absorbed simply circuit board to circuit board, not only through antenna > ports. Or it can even be injected in through the mPCI slot's pins or DC > power pins. > It might be interesting to try to discover for sure where exactly the > majority of the bleed is getting transferred from one card to the other, > to > know how to best isolate. > > Since you now have the Analyzer, and the know how to test, would you mind > repeating your tests, after inserting foil isolation (like I described > above), to see how it compares, to without foil isolation or to slots > positioned side by side alledged not to experience similar bleed levels? > > > Tom DeReggi > RapidDSL & Wireless, Inc > IntAirNet- Fixed Wireless Broadband > > > ----- Original Message ----- > From: "Robert West" <robert.w...@just-micro.com> > To: "'WISPA General List'" <wireless@wispa.org> > Sent: Friday, April 23, 2010 5:31 PM > Subject: Re: [WISPA] Ever wonder how bad RB333/444 stacked cards > interfere? > > >> Kurt, >> >> I always put laminated foil between the cards. You able to try putting a >> shield of aluminum foil between to see if that does anything useful? >> >> Bob- >> >> >> -----Original Message----- >> From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On >> Behalf Of Kurt Fankhauser >> Sent: Saturday, April 24, 2010 4:44 PM >> To: 'WISPA General List' >> Subject: Re: [WISPA] Ever wonder how bad RB333/444 stacked cards >> interfere? >> >> If you physically move them to anywhere but on top of each other, like >> the >> sides or above or below then the bleed over goes away. So if you mounted >> them side by side in a RB600 or RB800 then your ok. Heres some pics of >> that. >> >> >> Kurt Fankhauser >> WAVELINC >> P.O. Box 126 >> Bucyrus, OH 44820 >> 419-562-6405 >> www.wavelinc.com >> >> >> -----Original Message----- >> From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On >> Behalf Of Ryan Spott >> Sent: Friday, April 23, 2010 2:21 PM >> To: WISPA General List >> Subject: Re: [WISPA] Ever wonder how bad RB333/444 stacked cards >> interfere? >> >> Wow, >> >> So my question would be, what sort of separation is required to keep the >> noise down? >> >> ryan >> >> >> On Sat, Apr 24, 2010 at 8:27 AM, Kurt Fankhauser <k...@wavelinc.com> >> wrote: >> >>> If anyone is like me and ever wondered how bad that stacking cards of >>> the same band in RB333 or RB433 interfere with each other, well, I >>> finally answered my own question. I've been wondering this for the >>> past 3 years >> and >>> no one could really give an answer, or show proof. Well I bought a >> spectrum >>> analyzer and decided to do some testing. I plugged the spectrum >>> analyzer directly into the antenna port on a disabled card that was >>> stacked on top of a card that was transmitting. Bleed-over on the >>> adjacent channels started at >>> -76 !!!! >>> >>> >>> >>> Won't be doing that anymore! Just thought I would share this valuable >>> information with the list. For more tests at different channel widths >>> and such check out this thread. >>> >>> http://forum.mikrotik.com/viewtopic.php?f=7 >>> <http://forum.mikrotik.com/viewtopic.php?f=7&t=30657&p=204642#p204642> >>> &t=30657&p=204642#p204642 >>> >>> >>> >>> >>> >>> Kurt Fankhauser >>> WAVELINC >>> P.O. Box 126 >>> Bucyrus, OH 44820 >>> 419-562-6405 >>> www.wavelinc.com >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >> ---------------------------------------------------------------------------- >> ---- >>> WISPA Wants You! 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