Bob,
I don't have a way to measure this accurately on the receive side, but just using a signal generator and my ear, there appears to be about a 2 dB loss in the duplexer. On the transmit side, using a transmitter and Bird power meter, there is a 2 dB loss in the duplexer. Power in: 94 w; power out: 60 w. Reflected: 2 w. I don't have a good way to measure the isolation, but using a distant transmitter, that transmitter had to use about 2 w when the repeater transmitter was on and only 1 w when the repeater transmitter was off. It appeared to me that we were getting a little de-sensing. The motivation for this re-tuning of the duplexer is that the repeater doesn't hear as well as it used to, according to users. I am not concerned about losing a couple dB on the TX side. I am hoping, though, that a re-tuning will decrease the de-sensing and, perhaps, add a slight increase in sensitivity. The system does have a pre-amp that appears to give about 4 dB of gain. I look forward to your suggestions. John -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Wednesday, July 02, 2008 11:35 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Cables on Duplexer At 7/2/2008 06:11, you wrote: >We have a repeater operating on 448.375/443.375 MHz. The cans are marked >456.300/451.300. So I conclude they were re-tuned from a commercial band. >I suspect (don t really know) that the cables were not lengthened to be >quarter wave (electrical). I would like to make them the optimum length. >Also, could someone tell me whether the lengths of cables going to the tee >connector are significant? Any information and suggestions are >appreciated. Thanks. Is the duplexer not meeting its loss or isolation specs? Bob NO6B __________ NOD32 3192 (20080616) Information __________ This message was checked by NOD32 antivirus system. http://www.eset.com
