Hi John, I want to suggest that you check the preamp, make sure it didn't get hit by lightning, or overloaded, also (if possible check you cables, I have had some change things happened that appears that the receiver is to blame but not in all cases) Then check the receiver to make sure it still has its sensitivity 0.25 - 0.35uv, or better should be good. I will hate to touch the duplexer without making sure that these other components are checked.
Hope you get fix, let us know what you find, when you do. v44kai.....Joel. ----- Original Message ----- From: John Transue To: Repeater-Builder@yahoogroups.com Sent: Wednesday, July 02, 2008 12:38 PM Subject: RE: [Repeater-Builder] Cables on Duplexer 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 ------------------------------------------------------------------------------ No virus found in this incoming message. Checked by AVG. Version: 8.0.101 / Virus Database: 270.4.3/1528 - Release Date: 7/1/2008 7:26 AM
