At 9/3/2008 08:09, you wrote: >Desense (actual Cable-Q contributions) > >Hi John, > >There is a case where you can actually be fighting a complex >problem with unwanted contributions actually made/introduced >by the cable (feed-line) Q. To be more specific some combination >of the antenna, duplexer, hardware circuit(s) in addition to >or along with the coaxial cable. > >Where I'm going with all of this is... > >There have been example cases where unwanted product generation >has been "fixed" by replacing portions of the antenna system >coaxial cables with a less or lower Q cable. Some transmit >antenna combiner low-level generation issues have been addressed >with lower-Q coax jumpers.
Not really a fix. "Lower Q" in transmissionlinespeak is "lossy". Using a lossy cable to fix some interaction between, say a TX & duplexer and/or antenna is IMO a band-aid solution. >I have replaced higher-Q feed-lines with more resistive cable, >which in more than one case has solved an otherwise pesky gremlin >- grunge problem. Yes, attenuators can "fix" a lot of interference issues, if you don't need optimum sensitivity or most efficient TX power transfer out of your system. Particularly at low-level sites, I find I need all the performance I can get & have very little margin for any additional loss in either the TX or RX path. >One other item... pay attention to the actual RG-214 description >aka mfgrs label as there seem to be a larger number of clone >cables, which is not actually the mil-spec RG-214 cable "real >deal". The key phrase to watch out for is "RG-214 TYPE". I've seen copper shielded coax with this designation. Bob NO6B
