FW: [Repeater-Builder] Cables on Duplexer
Bob, Here it is again. Let me know if my message doesn't appear. Thanks. John -Original Message- From: John Transue [mailto:[EMAIL PROTECTED] Sent: Wednesday, July 02, 2008 1:39 PM To: 'Repeater-Builder@yahoogroups.com' 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
RE: [Repeater-Builder] Cables on Duplexer
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 netJohn Transue To: mailto:Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.comRepeater-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
RE: [Repeater-Builder] Cables on Duplexer
John: I'm not seeing your reply text. Please turn off all text formatting in your e-mail client resend as plain text. Thanks. Bob NO6B At 7/5/2008 06:32, you wrote: -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]John Transue To: mailto:Repeater-Builder@yahoogroups.commailto:Repeater-Builder%40yaho ogroups.comRepeater-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. 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
RE: [Repeater-Builder] Cables on Duplexer
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: Saturday, July 05, 2008 1:59 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Cables on Duplexer John: I'm not seeing your reply text. Please turn off all text formatting in your e-mail client resend as plain text. Thanks. Bob NO6B At 7/5/2008 06:32, you wrote: -Original Message- From: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com [mailto:Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com] On Behalf Of [EMAIL PROTECTED] mailto:no6b%40no6b.com Sent: Thursday, July 03, 2008 12:36 AM To: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com 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 netJohn Transue To: mailto:Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.commailto:Repeater-Builder%40yaho ogroups.comRepeater-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
[Repeater-Builder] Cables on Duplexer
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. John Transue AF4PD
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
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
Re: [Repeater-Builder] Cables on Duplexer
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
RE: [Repeater-Builder] Cables on Duplexer
I see no added text here, only my forwarded message. Bob NO6B At 7/2/2008 10:38, you wrote: -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
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]John Transue To: mailto:Repeater-Builder@yahoogroups.comRepeater-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. 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