Gary, I think you're on the ragged edge of duplexer performance. According to the calculation of CommShop for Windows, your power output of 25 watts, 145.450 MHz TX and 144.850 MHz RX, and assuming a 0.3 uV receive sensitivity at 12 dB SINAD, a duplexer requires 85.6 dB of isolation for no desense. These are ballpark and not absolute figures. I suspect that the technician may have tuned the loops for less insertion loss, which accounts for the slightly low isolation figures. What does your printout show for insertion loss at the pass frequencies? Which model Telewave duplexer do you have?
73, Eric Lemmon WB6FLY -----Original Message----- From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of garyp609 Sent: Saturday, July 26, 2008 1:45 PM To: [email protected] Subject: [Repeater-Builder] Re: How to figure cable length for duplexer? Does the amount of power output make a difference with isolation? The paperwork I got shows 82.3 isolation on RX and 81.5 on TX. It appears the printout was done from a spectrum analyzer when TESSCO tuned the duplexer. I am running 25 watts. 73's Gary K2ACY --- In [email protected] <mailto:Repeater-Builder%40yahoogroups.com> , wd8chl <[EMAIL PROTECTED]> wrote: > > > >>> Output frequency is 145.450 & input is > >> 144.850. How do > >> I figure out > >>> what length the cables should be between the rx side > >> and tx side > >> that > >>> connect to the T-Connector? Thanks and 73's ! > >>> > >>> Gary K2ACY
