Bob,
Thanks. I have someone with good equipment coming Sunday to check it out and re-tune as needed. I'll let you know what we found. Re the de-sense, there are two other antennas close by but both are for much higher frequencies. The three feed lines all go down the same conduit. We are using 7/8 Heliax and I believe the others are smaller Heliax or hard line. I plan to replace the cables in the cabinet when new cables (now ordered) are ready. John -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Thursday, July 03, 2008 12:36 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Cables on Duplexer At 7/2/2008 13:07, you wrote: >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: <mailto:[EMAIL PROTECTED] <mailto:jtransue%40cox.net> net>John Transue >>To: >><mailto:Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com> yahoogroups.com>Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com> 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. OK, now I see your reply. Don't know why this text wasn't there on your original reply. 2 dB is rather high for a UHF duplexer. However, you've only moved the duplexer less than 2% of it's original frequency, so I doubt that any of the cables would need to be replaced as a result of the frequency change. You're also experiencing a bit of desense as well. Might be worth rechecking the duplexer tuning & loss on good test equipment (spectrum analyzer with tracking gen. or better yet a VNA if you can get access to one). However, there are many other possible causes of desense. The most common I run into are mixes caused by bad hardware in the near field of the antenna (other bad antennas, feedline, loose tower joints, etc.). Bob NO6B __________ NOD32 3192 (20080616) Information __________ This message was checked by NOD32 antivirus system. http://www.eset.com
