----- Original Message ----- From: "Tom W8JI" <[email protected]> To: "TopBand" <[email protected]> Sent: Thursday, June 21, 2012 5:03 PM Subject: Re: Topband: Chokes for Beverages
>> The subject was LMR-400 which, of course, is not flooded and uses a >> tinned >> copper weave over aluminum foil. > > Sorry. My mistake. Its often hard to kep track the way a few go suddenly tangential. > > I thought the subject was receiving cables, related to Beverages, and > common > mode noise, and that somehow a parallel was drawn to a stb measurement on > LMR400, which was a "needles in a haystack" change anyway in the > application > of stubs when compared to antenna-to-antenna leakage paths. Thats a long sentence but yeah, thats where we started from yesterday. Ive been guilty of taking a side trip at times also (-; > > There is some real questionable information on stubs, and it doesn't have > much to do with receiving transmission line behavior anyway. > >> If they decided to go with flooding I might even use it outdoors. >> >> Of equal concern is the variety of crimp connector vendors as well as off >> brand 400 "type" cable. > > I don't hesitate to use "LMR400" types here, provided the cable is well > constructed. Some cables are pretty thin copper cladding on the center, > which can significantly impact loss on lower bands as current moves out of > the copper and into the core. Small CCS center cables can have much higher > loss than expected on low frequencies, so far as transmitting applications > go. > > 73 Tom I thought that the cladding still carried most all of the current since the RF resistance of the core forced it to. Even the very thin copper on RG-6 steel core loses very little signal at 160 which is where it starts to dip with about .15dB/100'. Im sure its much higher at 600M and on down but outside noise is very high down there on a Beverage to be noticable. Its also still a bit better than 8X; and CATV 11 is still straightlining at 1 MHz. Carl KM1H > _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
