Jeff, Most repeater builders will agree that jumpers inside the repeater cabinet should always be double-shielded, and that they should be either double silver-plated braided shields, or a flexible solid-copper shield such as Heli-Flex. Genuine RG-214/U or RG-142/U or RG-400/U cable is best, in my opinion. Stay away from dissimilar-metal cables like Belden 9913 and others that combine copper braided shields with aluminum foil. Avoid using any adapters or barrels. If your TX output jack is an N female and your duplexer input jack is an SO-239 (UHF), then you should make up a one-piece cable with an N male plug on one end and a PL-259 plug on the other end. Ideally, these should be crimp-on connectors that are silver-plated, with gold or silver plated center pins. The use of high-quality cable and connectors inside the cabinet will reduce the leakage between TX and RX to a very low level, which *may* marginally increase range due to a reduction and possible elimination of desense caused by TX signal ingress.
Since the range of any repeater is primarily limited by the repeater's ability to hear the distant portable or mobile stations, anything you can do to increase the repeater's receive signal level will increase range- up to a point. If your antenna has (for example) 200 feet of LDF2 (3/8") feedline, I can suggest changing the feedline to LDF4 (1/2") or even LDF5 (7/8") to achieve a significant range improvement. Another item to look at is the antenna. If the repeater is located at one side or end of the primary area of operation, an omnidirectional antenna is not the best choice. Sometimes, just changing an omni antenna for one with an offset pattern can make a huge difference. Since the subject repeater is used for a public-safety application, I would consider adding multiple receivers with a voting system. 73, Eric Lemmon WB6FLY -----Original Message----- From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of jstechnicalservice Sent: Thursday, May 08, 2008 10:31 AM To: [email protected] Subject: [Repeater-Builder] Best coax for short jumpers in repeater cabinet? I was hoping to get some opinions on the best coax to make jumpers for internal connections on a 152 Mhz public safety repeater. I'm currently using LMR400 and we can hit the repeater consistantly with a 5 watt handheld at 14 miles. The problem is we sometimes need around 15 to 16. I was hoping to improve performance as much as possible. Thanks Jeff Skaggs Concord-Greene FD
