At 1/27/2007 06:47, you wrote: >LMR-1200 has about .9dB loss for 100 feet >LDF4-50A has about 1.45dB loss for 100 feet > >At first glance, it looks like you can gain a little more than 1/2dB by >using LMR-1200. Now. the real world. LMR-1200 will require a jumper at >the top and the bottom of the cable run. (It's too big to connect directly >to the antenna or the duplexer at the bottom). This means that you will >have to have 4 additional connectors and 2 short lengths of jumper cable >when using LMR-1200. This will add up to much more loss than the 1/2dB >you saved by using LMR-1200.
Good N connectors are virtually lossless @ 450 MHz, & 4 ft. of RG-214 (2 ft. each jumper) has 0.2 dB loss. I know there's a difference of opinion on this subject, but I'd never directly connect LDF4-50 to an antenna. However, the real reason not to use LMR-1200 in duplex feeds is the braid-over-foil shield, which will eventually cause desense & IMD. The key word is "eventually": maybe 6 months after install, maybe 30 years. Nothing like solid copper to keep those stray electrons in line ;) Bob NO6B
