Ed, I agree, much cheaper cable can be made to last and might make more sense for some situations. Heliax is not made for "test" applications, but if care is taken not to bend or excessively flex the cable, and to not subject it to excess torsional loads (like changing antenna polarity) it does ok. The real problem, in a test lab especially, is that multiple people will be using the cables, and some are more careful than others. We even have situations where our clients will be using our cables in our lab - something that makes me cringe. How many times do you have to tell someone not to step on the cables before they get the idea? :-) For above 1GHz, cable toughness is a big problem. Step on a heliax cable (or any cable, for that matter) and you could ruin it, and it won't be obvious until you do a swept insertion loss verification. My experience has been that the armored Microcoax cable is very resilient to most of the abuse that will be seen in a busy lab environment. Perhaps the Gore cable is similar (I don't have any experience with those). If only one person is using a cable, and they know the limitations of the lower cost cables, then buying the low cost cables might make better sense. That may be the case in your situation, but certainly not in at least one of the previous labs where I worked. I will mention that the Microcoax cables (at least the ones that I referenced) can only be terminated by the manufacturer. That is good and bad. I am sure they can do a better job which results in a lower VSWR, but then you will probably not be able to repair a connection in the future. I've done a lot of cable terminations on RGxx and Heliax cables and take pride in doing a good job, but I've seen other lab personel that should find something to do other than work on cables. :-) Bob R.
--- On Wed, 7/20/11, Price, Edward <[email protected]> wrote: From: Price, Edward <[email protected]> Subject: RE: Low loss cables To: [email protected] Date: Wednesday, July 20, 2011, 10:58 AM I have mentioned this vendor before, but the question still pops up every couple of years. I use United Microwave Micropore 190 cable for my low-loss 18 GHz work. Let’s compare specs with that $2400 cable. A 15 meter run of Micropore 190 has about 20 dB attenuation, and with a male SMA at each end, costs about $400 (my guess). I suspect the loss is pretty much the same as the expensive cable, so where does the big cost difference come from? Well, the Micropore isn’t mechanically tough, it won’t handle 100 Watts at 18 GHz, it likely doesn’t like UV exposure, and you have to buy a specific cable length from the vendor (they affix the connectors). In my lab environment, as long as I treat my cables with care, I can have a whole set of Micropore cables for the cost of a single $2400 cable. Sure, I have a few Gore cables (also check out Storm Products for good, expensive cables), but they cost so much I try to use them only when absolutely necessary. Of course, the Micropore isn’t for every use, but a cable shouldn’t be over-specified any more than any other component. http://www.unitedmicrowave.com/Resource/190.jpg http://www.stormproducts.com/microwave/product-finder-fx.asp http://www.gore.com/en_xx/products/cables/coaxial/index.html Ed Price [email protected] WB6WSN NARTE Certified EMC Engineer Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 Military & Avionics EMC Is Our Specialty From: [email protected] [mailto:[email protected]] On Behalf Of Bob Richards Sent: Wednesday, July 20, 2011 6:34 AM To: Ken MacGrath; [email protected] Subject: Re: Low loss cables Ken, We have been replacing our older emissions cables with those from Microcoax. www.microcoax.com <http://www.microcoax.com/> . Expensive, but really good cable. We have a couple of cables for testing up to 26.5 GHz, which is the MKR300C ruggedized cable. We also have one cable for up to 40 GHz, MKR240A. And we just ordered a 15m cable (to antenna mast) for up to 18GHz, UFB293C with optional armor and precision N connectors. That last cable is over $2400. Whatever cables you get from Microcoax, get the "test" cables and not the "hookup" cables. The "test" cables are rated much higher for flexure, the "hookup" is made more for a cable that will be installed and not moved around afterwards. Bob R. --- On Tue, 7/19/11, Ken MacGrath <[email protected]> wrote: From: Ken MacGrath <[email protected]> Subject: Low loss cables To: [email protected] Date: Tuesday, July 19, 2011, 9:04 PM Hello All, I'd appreciate any/all cables recommendations for a rugged low loss cable for radiated emissions testing at 10 meters, and cables for radiated immunity (61000-4-3). Thanks in advance! 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