[Repeater-Builder] Re: Help with intermod between repeaters.
Thanks to all for your replies. Joe M wrote You need to reject the opposite TX on each repeater. Your BP filters were set wrong. You rejected the RX on the TX side - something the duplexer should be doing already. You need to install them in the repeater and reject the other TX. IOW, install a filter in the .16 repeater and notch the .36 TX. A good duplexer should do this as well, but many don't. Joe that's what I thought I did. Maybe I did not make myself clear. I put a BPBR cavity rejecting 146.76 and passing 147.36 between the repeater transmitter and the duplexer at the 147.36 repeater. This is where I was surprised that the mixing got worse. If I put the cavity in the wrong place let me know. Eric Lemmon WB6FLY wrote The first question that enters my mind is, were both Micor stations originally built as repeaters, with the extra filters and shielding plates,or are one or both base stations that have been converted to repeaters? I built our repeater. It's the 146.76 machine. It was originally a pager TX. All shielding and the lo pass TX filter is in place. I have looked at it with a spectrum analyzer and see no other signal than 146.76. I have no idea as to what the other repeater was made from. I will take a second look at their TX. The next time I go down there I plan to take a 50 watt radio and connect it to their duplexer to try to eliminate or prove their PA has a problem. The second question is, are either or both repeaters equipped with ferrite isolators? The 146.76 has no isolator. The 147.36 has a brand new, I believe Sinclair, isolator that was factory built for this frequency. The isolator has no affect on the problem although I don't think it's installed properly. I did not notice when I was there but I think it's mounted on a steel plate. Also there in no cavity between it and the duplexer. The mixing is there with or without the isolator in line. They paid big bucks thinking this would fix the problem. By the way they also replaced their antenna and feed line which may have made the mixing worse. John wrote I hate to tell you, a definite way to eliminate the problem, is a frequency change so that the output of the two transmitters are no longer not 600 khz apart. Funny that`s the first thing I told them. I am familiar with two pagers 600 khz apart and the havoc that can be raised. I plan to go back down there when I have time and let the group know what I find. Again thanks to all.
Re: [Repeater-Builder] Re: Help with intermod between repeaters.
Joe you dont have any PL tone???on your repeaters gervais ve2ckn -- From: wa5luy wa5...@cablelynx.com Sent: Sunday, February 15, 2009 8:15 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Help with intermod between repeaters. Thanks to all for your replies. Joe M wrote You need to reject the opposite TX on each repeater. Your BP filters were set wrong. You rejected the RX on the TX side - something the duplexer should be doing already. You need to install them in the repeater and reject the other TX. IOW, install a filter in the .16 repeater and notch the .36 TX. A good duplexer should do this as well, but many don't. Joe that's what I thought I did. Maybe I did not make myself clear. I put a BPBR cavity rejecting 146.76 and passing 147.36 between the repeater transmitter and the duplexer at the 147.36 repeater. This is where I was surprised that the mixing got worse. If I put the cavity in the wrong place let me know. Eric Lemmon WB6FLY wrote The first question that enters my mind is, were both Micor stations originally built as repeaters, with the extra filters and shielding plates,or are one or both base stations that have been converted to repeaters? I built our repeater. It's the 146.76 machine. It was originally a pager TX. All shielding and the lo pass TX filter is in place. I have looked at it with a spectrum analyzer and see no other signal than 146.76. I have no idea as to what the other repeater was made from. I will take a second look at their TX. The next time I go down there I plan to take a 50 watt radio and connect it to their duplexer to try to eliminate or prove their PA has a problem. The second question is, are either or both repeaters equipped with ferrite isolators? The 146.76 has no isolator. The 147.36 has a brand new, I believe Sinclair, isolator that was factory built for this frequency. The isolator has no affect on the problem although I don't think it's installed properly. I did not notice when I was there but I think it's mounted on a steel plate. Also there in no cavity between it and the duplexer. The mixing is there with or without the isolator in line. They paid big bucks thinking this would fix the problem. By the way they also replaced their antenna and feed line which may have made the mixing worse. John wrote I hate to tell you, a definite way to eliminate the problem, is a frequency change so that the output of the two transmitters are no longer not 600 khz apart. Funny that`s the first thing I told them. I am familiar with two pagers 600 khz apart and the havoc that can be raised. I plan to go back down there when I have time and let the group know what I find. Again thanks to all. Yahoo! Groups Links
Re: [Repeater-Builder] Re: Help with intermod between repeaters.
It looks like the mix is: 2X146.76 - 147.36 = 146.16Mhz 2X146.76 = 293.52Mhz would have to be made somewhere for the mix to occur. I would think that the most logical point would be in your final PA stage. Have you sniffed around your PA stage with a short probe to see if you have 293.52 and 146.16 being created in this stage? 73, Joe, K1ike
Re: [Repeater-Builder] Re: Help with intermod between repeaters.
This is one of the toughest intermod products to solve. 2 transmitters 600 kHz apart generate spurs every 600 kHz on both sides of each transmitter. When we were co-ordinating repeaters, it's one parameter we always looked at, and tried to keep nearby repeaters off of that 600 KHZ separation boundary. Are Both repeaters having problems or just yours? These signals don't even have to be generated in your equipment, I've seen them generated by stuff externally and if you look at a spectrum analyzer when both transmitters are on the air, you'll see the Christmas tree like display showing the spikes every 600 kHz decreasing with amplitude as they get farther away. Most suggestions made may help and all I can say is good luck, the only real way out of this problem may be a frequency change for one or the other machine.] Gary - K7NEY - Original Message - From: wa5luy To: Repeater-Builder@yahoogroups.com Sent: Sunday, February 15, 2009 6:15 AM Subject: [Repeater-Builder] Re: Help with intermod between repeaters. Thanks to all for your replies. Joe M wrote You need to reject the opposite TX on each repeater. Your BP filters were set wrong. You rejected the RX on the TX side - something the duplexer should be doing already. You need to install them in the repeater and reject the other TX. IOW, install a filter in the .16 repeater and notch the .36 TX. A good duplexer should do this as well, but many don't. Joe that's what I thought I did. Maybe I did not make myself clear. I put a BPBR cavity rejecting 146.76 and passing 147.36 between the repeater transmitter and the duplexer at the 147.36 repeater. This is where I was surprised that the mixing got worse. If I put the cavity in the wrong place let me know. Eric Lemmon WB6FLY wrote The first question that enters my mind is, were both Micor stations originally built as repeaters, with the extra filters and shielding plates,or are one or both base stations that have been converted to repeaters? I built our repeater. It's the 146.76 machine. It was originally a pager TX. All shielding and the lo pass TX filter is in place. I have looked at it with a spectrum analyzer and see no other signal than 146.76. I have no idea as to what the other repeater was made from. I will take a second look at their TX. The next time I go down there I plan to take a 50 watt radio and connect it to their duplexer to try to eliminate or prove their PA has a problem. The second question is, are either or both repeaters equipped with ferrite isolators? The 146.76 has no isolator. The 147.36 has a brand new, I believe Sinclair, isolator that was factory built for this frequency. The isolator has no affect on the problem although I don't think it's installed properly. I did not notice when I was there but I think it's mounted on a steel plate. Also there in no cavity between it and the duplexer. The mixing is there with or without the isolator in line. They paid big bucks thinking this would fix the problem. By the way they also replaced their antenna and feed line which may have made the mixing worse. John wrote I hate to tell you, a definite way to eliminate the problem, is a frequency change so that the output of the two transmitters are no longer not 600 khz apart. Funny that`s the first thing I told them. I am familiar with two pagers 600 khz apart and the havoc that can be raised. I plan to go back down there when I have time and let the group know what I find. Again thanks to all.
Re: [Repeater-Builder] Re: Help with intermod between repeaters.
well said - Original Message - From: Gary Hoff To: Repeater-Builder@yahoogroups.com Sent: Sunday, February 15, 2009 10:33 AM Subject: Re: [Repeater-Builder] Re: Help with intermod between repeaters. This is one of the toughest intermod products to solve. 2 transmitters 600 kHz apart generate spurs every 600 kHz on both sides of each transmitter. When we were co-ordinating repeaters, it's one parameter we always looked at, and tried to keep nearby repeaters off of that 600 KHZ separation boundary. Are Both repeaters having problems or just yours? These signals don't even have to be generated in your equipment, I've seen them generated by stuff externally and if you look at a spectrum analyzer when both transmitters are on the air, you'll see the Christmas tree like display showing the spikes every 600 kHz decreasing with amplitude as they get farther away. Most suggestions made may help and all I can say is good luck, the only real way out of this problem may be a frequency change for one or the other machine.] Gary - K7NEY - Original Message - From: wa5luy To: Repeater-Builder@yahoogroups.com Sent: Sunday, February 15, 2009 6:15 AM Subject: [Repeater-Builder] Re: Help with intermod between repeaters. Thanks to all for your replies. Joe M wrote You need to reject the opposite TX on each repeater. Your BP filters were set wrong. You rejected the RX on the TX side - something the duplexer should be doing already. You need to install them in the repeater and reject the other TX. IOW, install a filter in the .16 repeater and notch the .36 TX. A good duplexer should do this as well, but many don't. Joe that's what I thought I did. Maybe I did not make myself clear. I put a BPBR cavity rejecting 146.76 and passing 147.36 between the repeater transmitter and the duplexer at the 147.36 repeater. This is where I was surprised that the mixing got worse. If I put the cavity in the wrong place let me know. Eric Lemmon WB6FLY wrote The first question that enters my mind is, were both Micor stations originally built as repeaters, with the extra filters and shielding plates,or are one or both base stations that have been converted to repeaters? I built our repeater. It's the 146.76 machine. It was originally a pager TX. All shielding and the lo pass TX filter is in place. I have looked at it with a spectrum analyzer and see no other signal than 146.76. I have no idea as to what the other repeater was made from. I will take a second look at their TX. The next time I go down there I plan to take a 50 watt radio and connect it to their duplexer to try to eliminate or prove their PA has a problem. The second question is, are either or both repeaters equipped with ferrite isolators? The 146.76 has no isolator. The 147.36 has a brand new, I believe Sinclair, isolator that was factory built for this frequency. The isolator has no affect on the problem although I don't think it's installed properly. I did not notice when I was there but I think it's mounted on a steel plate. Also there in no cavity between it and the duplexer. The mixing is there with or without the isolator in line. They paid big bucks thinking this would fix the problem. By the way they also replaced their antenna and feed line which may have made the mixing worse. John wrote I hate to tell you, a definite way to eliminate the problem, is a frequency change so that the output of the two transmitters are no longer not 600 khz apart. Funny that`s the first thing I told them. I am familiar with two pagers 600 khz apart and the havoc that can be raised. I plan to go back down there when I have time and let the group know what I find. Again thanks to all. -- Checked by AVG - www.avg.com Version: 8.0.237 / Virus Database: 270.10.23/1953 - Release Date: 02/14/09 18:01:00
Re: [Repeater-Builder] Re: Help with intermod between repeaters.
When were these two repeaters coordinated? RX freq so close to the TX freq of the other repeater doesn't exactly sound like a good engineering practices, even with 18 miles between the two sites... On Sun, Feb 15, 2009 at 9:37 AM, Gary Glaenzer glaen...@verizon.net wrote: well said - Original Message - *From:* Gary Hoff k7ney...@q.com *To:* Repeater-Builder@yahoogroups.com *Sent:* Sunday, February 15, 2009 10:33 AM *Subject:* Re: [Repeater-Builder] Re: Help with intermod between repeaters. *This is one of the toughest intermod products to solve. 2 transmitters* *600 kHz apart generate spurs every 600 kHz on both sides of each* *transmitter. When we were co-ordinating repeaters, it's one parameter* *we always looked at, and tried to keep nearby repeaters off of that* *600 KHZ separation boundary. Are Both repeaters having problems or just yours?* *These signals don't even have to be generated in your equipment,* *I've seen them generated by stuff externally and if you look at a * *spectrum analyzer when both transmitters are on the air, you'll see* *the Christmas tree like display showing the spikes every 600 kHz decreasing* *with amplitude as they get farther away. Most suggestions made may* *help and all I can say is good luck, the only real way out of this* *problem may be a frequency change for one or the other machine.]* *Gary - K7NEY* - Original Message - *From:* wa5luy wa5...@cablelynx.com *To:* Repeater-Builder@yahoogroups.com *Sent:* Sunday, February 15, 2009 6:15 AM *Subject:* [Repeater-Builder] Re: Help with intermod between repeaters. Thanks to all for your replies. Joe M wrote You need to reject the opposite TX on each repeater. Your BP filters were set wrong. You rejected the RX on the TX side - something the duplexer should be doing already. You need to install them in the repeater and reject the other TX. IOW, install a filter in the .16 repeater and notch the .36 TX. A good duplexer should do this as well, but many don't. Joe that's what I thought I did. Maybe I did not make myself clear. I put a BPBR cavity rejecting 146.76 and passing 147.36 between the repeater transmitter and the duplexer at the 147.36 repeater. This is where I was surprised that the mixing got worse. If I put the cavity in the wrong place let me know. Eric Lemmon WB6FLY wrote The first question that enters my mind is, were both Micor stations originally built as repeaters, with the extra filters and shielding plates,or are one or both base stations that have been converted to repeaters? I built our repeater. It's the 146.76 machine. It was originally a pager TX. All shielding and the lo pass TX filter is in place. I have looked at it with a spectrum analyzer and see no other signal than 146.76. I have no idea as to what the other repeater was made from. I will take a second look at their TX. The next time I go down there I plan to take a 50 watt radio and connect it to their duplexer to try to eliminate or prove their PA has a problem. The second question is, are either or both repeaters equipped with ferrite isolators? The 146.76 has no isolator. The 147.36 has a brand new, I believe Sinclair, isolator that was factory built for this frequency. The isolator has no affect on the problem although I don't think it's installed properly. I did not notice when I was there but I think it's mounted on a steel plate. Also there in no cavity between it and the duplexer. The mixing is there with or without the isolator in line. They paid big bucks thinking this would fix the problem. By the way they also replaced their antenna and feed line which may have made the mixing worse. John wrote I hate to tell you, a definite way to eliminate the problem, is a frequency change so that the output of the two transmitters are no longer not 600 khz apart. Funny that`s the first thing I told them. I am familiar with two pagers 600 khz apart and the havoc that can be raised. I plan to go back down there when I have time and let the group know what I find. Again thanks to all. -- Checked by AVG - www.avg.com Version: 8.0.237 / Virus Database: 270.10.23/1953 - Release Date: 02/14/09 18:01:00
Re: [Repeater-Builder] Re: Help with intermod between repeaters.
Hi , I am quite sure the IMD from ( 2A- B ) the 2 x TX frequency . Please try kill it make it as low as possible . Will work for this issue But base on no other object produce IMD out side both transmitters. Good luck 73s de VR2XVD On 2/15/09, Joe k1ike_m...@snet.net wrote: It looks like the mix is: 2X146.76 - 147.36 = 146.16Mhz 2X146.76 = 293.52Mhz would have to be made somewhere for the mix to occur. I would think that the most logical point would be in your final PA stage. Have you sniffed around your PA stage with a short probe to see if you have 293.52 and 146.16 being created in this stage? 73, Joe, K1ike -- HKARA website : http://www.hkara.org.hk VR2XVD email : vr2...@yahoo.com,vr2...@gmail.com Please consider the environment before printing the email.
Re: [Repeater-Builder] Re: Help with intermod between repeaters.
18 miles apart and 1.2 MHz separation? How far apart do you want to space repeaters? I know of repeaters only 210 kHz apart at the same site that work fine. Joe M. AJ wrote: When were these two repeaters coordinated? RX freq so close to the TX freq of the other repeater doesn't exactly sound like a good engineering practices, even with 18 miles between the two sites... On Sun, Feb 15, 2009 at 9:37 AM, Gary Glaenzer glaen...@verizon.net mailto:glaen...@verizon.net wrote: well said - Original Message - *From:* Gary Hoff mailto:k7ney...@q.com *To:* Repeater-Builder@yahoogroups.com mailto:Repeater-Builder@yahoogroups.com *Sent:* Sunday, February 15, 2009 10:33 AM *Subject:* Re: [Repeater-Builder] Re: Help with intermod between repeaters. */This is one of the toughest intermod products to solve. 2 transmitters/* */600 kHz apart generate spurs every 600 kHz on both sides of each/* */transmitter. When we were co-ordinating repeaters, it's one parameter/* */we always looked at, and tried to keep nearby repeaters off of that/* */600 KHZ separation boundary. Are Both repeaters having problems or just yours?/* */These signals don't even have to be generated in your equipment,/* */I've seen them generated by stuff externally and if you look at a /* */spectrum analyzer when both transmitters are on the air, you'll see/* */the Christmas tree like display showing the spikes every 600 kHz decreasing/* */with amplitude as they get farther away. Most suggestions made may/* */help and all I can say is good luck, the only real way out of this/* */problem may be a frequency change for one or the other machine.]/* */Gary - K7NEY/* - Original Message - *From:* wa5luy mailto:wa5...@cablelynx.com *To:* Repeater-Builder@yahoogroups.com mailto:Repeater-Builder@yahoogroups.com *Sent:* Sunday, February 15, 2009 6:15 AM *Subject:* [Repeater-Builder] Re: Help with intermod between repeaters. Thanks to all for your replies. Joe M wrote You need to reject the opposite TX on each repeater. Your BP filters were set wrong. You rejected the RX on the TX side - something the duplexer should be doing already. You need to install them in the repeater and reject the other TX. IOW, install a filter in the .16 repeater and notch the .36 TX. A good duplexer should do this as well, but many don't. Joe that's what I thought I did. Maybe I did not make myself clear. I put a BPBR cavity rejecting 146.76 and passing 147.36 between the repeater transmitter and the duplexer at the 147.36 repeater. This is where I was surprised that the mixing got worse. If I put the cavity in the wrong place let me know. Eric Lemmon WB6FLY wrote The first question that enters my mind is, were both Micor stations originally built as repeaters, with the extra filters and shielding plates,or are one or both base stations that have been converted to repeaters? I built our repeater. It's the 146.76 machine. It was originally a pager TX. All shielding and the lo pass TX filter is in place. I have looked at it with a spectrum analyzer and see no other signal than 146.76. I have no idea as to what the other repeater was made from. I will take a second look at their TX. The next time I go down there I plan to take a 50 watt radio and connect it to their duplexer to try to eliminate or prove their PA has a problem. The second question is, are either or both repeaters equipped with ferrite isolators? The 146.76 has no isolator. The 147.36 has a brand new, I believe Sinclair, isolator that was factory built for this frequency. The isolator has no affect on the problem although I don't think it's installed properly. I did not notice when I was there but I think it's mounted on a steel plate. Also there in no cavity between it and the duplexer. The mixing is there with or without the isolator in line. They paid big bucks thinking this would fix
RE: [Repeater-Builder] Re: Help with intermod between repeaters.
Joe, The transmit frequencies are separated by 600 kHz, not 1.2 MHz (147.360 - 146.760 = 600 kHz), which causes mixing products to fall exactly on the inputs. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of MCH Sent: Sunday, February 15, 2009 11:19 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Help with intermod between repeaters. 18 miles apart and 1.2 MHz separation? How far apart do you want to space repeaters? I know of repeaters only 210 kHz apart at the same site that work fine. Joe M. AJ wrote: When were these two repeaters coordinated? RX freq so close to the TX freq of the other repeater doesn't exactly sound like a good engineering practices, even with 18 miles between the two sites... On Sun, Feb 15, 2009 at 9:37 AM, Gary Glaenzer glaen...@verizon.net mailto:glaenzer%40verizon.net mailto:glaen...@verizon.net mailto:glaenzer%40verizon.net wrote: well said - Original Message - *From:* Gary Hoff mailto:k7ney...@q.com mailto:k7ney123%40q.com *To:* Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com *Sent:* Sunday, February 15, 2009 10:33 AM *Subject:* Re: [Repeater-Builder] Re: Help with intermod between repeaters. */This is one of the toughest intermod products to solve. 2 transmitters/* */600 kHz apart generate spurs every 600 kHz on both sides of each/* */transmitter. When we were co-ordinating repeaters, it's one parameter/* */we always looked at, and tried to keep nearby repeaters off of that/* */600 KHZ separation boundary. Are Both repeaters having problems or just yours?/* */These signals don't even have to be generated in your equipment,/* */I've seen them generated by stuff externally and if you look at a /* */spectrum analyzer when both transmitters are on the air, you'll see/* */the Christmas tree like display showing the spikes every 600 kHz decreasing/* */with amplitude as they get farther away. Most suggestions made may/* */help and all I can say is good luck, the only real way out of this/* */problem may be a frequency change for one or the other machine.]/* */Gary - K7NEY/* - Original Message - *From:* wa5luy mailto:wa5...@cablelynx.com mailto:wa5luy%40cablelynx.com *To:* Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com *Sent:* Sunday, February 15, 2009 6:15 AM *Subject:* [Repeater-Builder] Re: Help with intermod between repeaters. Thanks to all for your replies. Joe M wrote You need to reject the opposite TX on each repeater. Your BP filters were set wrong. You rejected the RX on the TX side - something the duplexer should be doing already. You need to install them in the repeater and reject the other TX. IOW, install a filter in the .16 repeater and notch the .36 TX. A good duplexer should do this as well, but many don't. Joe that's what I thought I did. Maybe I did not make myself clear. I put a BPBR cavity rejecting 146.76 and passing 147.36 between the repeater transmitter and the duplexer at the 147.36 repeater. This is where I was surprised that the mixing got worse. If I put the cavity in the wrong place let me know. Eric Lemmon WB6FLY wrote The first question that enters my mind is, were both Micor stations originally built as repeaters, with the extra filters and shielding plates,or are one or both base stations that have been converted to repeaters? I built our repeater. It's the 146.76 machine. It was originally a pager TX. All shielding and the lo pass TX filter is in place. I have looked at it with a spectrum analyzer and see no other signal than 146.76. I have no idea as to what the other repeater was made from. I will take a second look at their TX. The next time I go down there I plan to take a 50 watt radio and connect it to their duplexer to try to eliminate or prove their PA has a problem. The second question is, are either or both repeaters equipped with ferrite isolators? The 146.76 has no isolator. The 147.36 has a brand new, I believe Sinclair, isolator that was factory built for this frequency. The isolator has no affect on the problem although I don't think it's installed properly. I did not notice when I was there but I think it's mounted on a steel plate. Also there in no cavity between it and the duplexer. The mixing is there with or without the isolator in line. They paid big bucks thinking this would fix the problem. By the way they also replaced their antenna and feed line which may have made the mixing worse. John wrote I hate to tell you, a definite way to eliminate the problem, is a frequency change so that the output of the two transmitters
Re: [Repeater-Builder] Re: Help with intermod between repeaters.
I know, TX separation is not what he was talking about. RX freq so close to the TX freq of the other repeater doesn't exactly sound like a good engineering practices Either RX is 1.2 MHz away from the other TX. So, my reply was accurate. Joe M. Eric Lemmon wrote: Joe, The transmit frequencies are separated by 600 kHz, not 1.2 MHz (147.360 - 146.760 = 600 kHz), which causes mixing products to fall exactly on the inputs. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of MCH Sent: Sunday, February 15, 2009 11:19 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Help with intermod between repeaters. 18 miles apart and 1.2 MHz separation? How far apart do you want to space repeaters? I know of repeaters only 210 kHz apart at the same site that work fine. Joe M. AJ wrote: When were these two repeaters coordinated? RX freq so close to the TX freq of the other repeater doesn't exactly sound like a good engineering practices, even with 18 miles between the two sites... On Sun, Feb 15, 2009 at 9:37 AM, Gary Glaenzer glaen...@verizon.net mailto:glaenzer%40verizon.net mailto:glaen...@verizon.net mailto:glaenzer%40verizon.net wrote: well said - Original Message - *From:* Gary Hoff mailto:k7ney...@q.com mailto:k7ney123%40q.com *To:* Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com *Sent:* Sunday, February 15, 2009 10:33 AM *Subject:* Re: [Repeater-Builder] Re: Help with intermod between repeaters. */This is one of the toughest intermod products to solve. 2 transmitters/* */600 kHz apart generate spurs every 600 kHz on both sides of each/* */transmitter. When we were co-ordinating repeaters, it's one parameter/* */we always looked at, and tried to keep nearby repeaters off of that/* */600 KHZ separation boundary. Are Both repeaters having problems or just yours?/* */These signals don't even have to be generated in your equipment,/* */I've seen them generated by stuff externally and if you look at a /* */spectrum analyzer when both transmitters are on the air, you'll see/* */the Christmas tree like display showing the spikes every 600 kHz decreasing/* */with amplitude as they get farther away. Most suggestions made may/* */help and all I can say is good luck, the only real way out of this/* */problem may be a frequency change for one or the other machine.]/* */Gary - K7NEY/* - Original Message - *From:* wa5luy mailto:wa5...@cablelynx.com mailto:wa5luy%40cablelynx.com *To:* Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com *Sent:* Sunday, February 15, 2009 6:15 AM *Subject:* [Repeater-Builder] Re: Help with intermod between repeaters. Thanks to all for your replies. Joe M wrote You need to reject the opposite TX on each repeater. Your BP filters were set wrong. You rejected the RX on the TX side - something the duplexer should be doing already. You need to install them in the repeater and reject the other TX. IOW, install a filter in the .16 repeater and notch the .36 TX. A good duplexer should do this as well, but many don't. Joe that's what I thought I did. Maybe I did not make myself clear. I put a BPBR cavity rejecting 146.76 and passing 147.36 between the repeater transmitter and the duplexer at the 147.36 repeater. This is where I was surprised that the mixing got worse. If I put the cavity in the wrong place let me know. Eric Lemmon WB6FLY wrote The first question that enters my mind is, were both Micor stations originally built as repeaters, with the extra filters and shielding plates,or are one or both base stations that have been converted to repeaters? I built our repeater. It's the 146.76 machine. It was originally a pager TX. All shielding and the lo pass TX filter is in place. I have looked at it with a spectrum analyzer and see no other signal than 146.76. I have no idea as to what the other repeater was made from. I will take a second look at their TX. The next time I go down there I plan to take a 50 watt radio and connect it to their duplexer to try to eliminate or prove their PA has a problem. The second question is, are either or both repeaters equipped with ferrite isolators? The 146.76 has no isolator. The 147.36 has a brand new, I believe Sinclair, isolator that was factory built for this frequency. The isolator has no affect on the problem although I don't think it's installed properly. I did not notice when I was there but I think it's mounted on a steel plate. Also there in no cavity between it and the duplexer. The mixing is there with or without the isolator in line. They paid big bucks
Re: [Repeater-Builder] Re: Help with intermod between repeaters.
Has nothing to do with the spacing, but with the intermod products generated by the two transmitters exactly 600 kHz apart generating spurious signals on the inputs of the receivers. Gary - K7NEY - Original Message - From: MCH To: Repeater-Builder@yahoogroups.com Sent: Sunday, February 15, 2009 12:19 PM Subject: Re: [Repeater-Builder] Re: Help with intermod between repeaters. 18 miles apart and 1.2 MHz separation? How far apart do you want to space repeaters? I know of repeaters only 210 kHz apart at the same site that work fine. Joe M. AJ wrote: When were these two repeaters coordinated? RX freq so close to the TX freq of the other repeater doesn't exactly sound like a good engineering practices, even with 18 miles between the two sites... On Sun, Feb 15, 2009 at 9:37 AM, Gary Glaenzer glaen...@verizon.net mailto:glaen...@verizon.net wrote: well said - Original Message - *From:* Gary Hoff mailto:k7ney...@q.com *To:* Repeater-Builder@yahoogroups.com mailto:Repeater-Builder@yahoogroups.com *Sent:* Sunday, February 15, 2009 10:33 AM *Subject:* Re: [Repeater-Builder] Re: Help with intermod between repeaters. */This is one of the toughest intermod products to solve. 2 transmitters/* */600 kHz apart generate spurs every 600 kHz on both sides of each/* */transmitter. When we were co-ordinating repeaters, it's one parameter/* */we always looked at, and tried to keep nearby repeaters off of that/* */600 KHZ separation boundary. Are Both repeaters having problems or just yours?/* */These signals don't even have to be generated in your equipment,/* */I've seen them generated by stuff externally and if you look at a /* */spectrum analyzer when both transmitters are on the air, you'll see/* */the Christmas tree like display showing the spikes every 600 kHz decreasing/* */with amplitude as they get farther away. Most suggestions made may/* */help and all I can say is good luck, the only real way out of this/* */problem may be a frequency change for one or the other machine.]/* */Gary - K7NEY/* - Original Message - *From:* wa5luy mailto:wa5...@cablelynx.com *To:* Repeater-Builder@yahoogroups.com mailto:Repeater-Builder@yahoogroups.com *Sent:* Sunday, February 15, 2009 6:15 AM *Subject:* [Repeater-Builder] Re: Help with intermod between repeaters. Thanks to all for your replies. Joe M wrote You need to reject the opposite TX on each repeater. Your BP filters were set wrong. You rejected the RX on the TX side - something the duplexer should be doing already. You need to install them in the repeater and reject the other TX. IOW, install a filter in the .16 repeater and notch the .36 TX. A good duplexer should do this as well, but many don't. Joe that's what I thought I did. Maybe I did not make myself clear. I put a BPBR cavity rejecting 146.76 and passing 147.36 between the repeater transmitter and the duplexer at the 147.36 repeater. This is where I was surprised that the mixing got worse. If I put the cavity in the wrong place let me know. Eric Lemmon WB6FLY wrote The first question that enters my mind is, were both Micor stations originally built as repeaters, with the extra filters and shielding plates,or are one or both base stations that have been converted to repeaters? I built our repeater. It's the 146.76 machine. It was originally a pager TX. All shielding and the lo pass TX filter is in place. I have looked at it with a spectrum analyzer and see no other signal than 146.76. I have no idea as to what the other repeater was made from. I will take a second look at their TX. The next time I go down there I plan to take a 50 watt radio and connect it to their duplexer to try to eliminate or prove their PA has a problem. The second question is, are either or both repeaters equipped with ferrite isolators? The 146.76 has no isolator. The 147.36 has a brand new, I believe Sinclair, isolator that was factory built for this frequency. The isolator has no affect on the problem although I don't think it's installed properly. I did not notice when I was there but I think it's mounted on a steel plate. Also there in no cavity between it and the duplexer. The mixing is there with or without the isolator in line. They paid big bucks thinking this would fix the problem. By the way they also replaced their antenna and feed line which may have made the mixing worse. John wrote I hate to tell you, a definite way to eliminate the problem, is a frequency change so that the output of the two transmitters are no longer not 600 khz apart. Funny that`s the first thing I told them. I am familiar
Re: [Repeater-Builder] Re: Help with intermod between repeaters.
Again, I know. Respond to AJ's post. He is the one saying 1.2 MHz is too close for a TX to be to a RX that is 'only 18 miles away'. Joe M. Gary Hoff wrote: */Has nothing to do with the spacing, but with the intermod/* */products generated by the two transmitters exactly 600 kHz apart/* */generating spurious signals on the inputs of the receivers./* */Gary - K7NEY/* - Original Message - *From:* MCH mailto:m...@nb.net *To:* Repeater-Builder@yahoogroups.com mailto:Repeater-Builder@yahoogroups.com *Sent:* Sunday, February 15, 2009 12:19 PM *Subject:* Re: [Repeater-Builder] Re: Help with intermod between repeaters. 18 miles apart and 1.2 MHz separation? How far apart do you want to space repeaters? I know of repeaters only 210 kHz apart at the same site that work fine. Joe M. AJ wrote: When were these two repeaters coordinated? RX freq so close to the TX freq of the other repeater doesn't exactly sound like a good engineering practices, even with 18 miles between the two sites... On Sun, Feb 15, 2009 at 9:37 AM, Gary Glaenzer glaen...@verizon.net mailto:glaenzer%40verizon.net mailto:glaen...@verizon.net mailto:glaenzer%40verizon.net wrote: well said - Original Message - *From:* Gary Hoff mailto:k7ney...@q.com mailto:k7ney123%40q.com *To:* Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com *Sent:* Sunday, February 15, 2009 10:33 AM *Subject:* Re: [Repeater-Builder] Re: Help with intermod between repeaters. */This is one of the toughest intermod products to solve. 2 transmitters/* */600 kHz apart generate spurs every 600 kHz on both sides of each/* */transmitter. When we were co-ordinating repeaters, it's one parameter/* */we always looked at, and tried to keep nearby repeaters off of that/* */600 KHZ separation boundary. Are Both repeaters having problems or just yours?/* */These signals don't even have to be generated in your equipment,/* */I've seen them generated by stuff externally and if you look at a /* */spectrum analyzer when both transmitters are on the air, you'll see/* */the Christmas tree like display showing the spikes every 600 kHz decreasing/* */with amplitude as they get farther away. Most suggestions made may/* */help and all I can say is good luck, the only real way out of this/* */problem may be a frequency change for one or the other machine.]/* */Gary - K7NEY/* - Original Message - *From:* wa5luy mailto:wa5...@cablelynx.com mailto:wa5luy%40cablelynx.com *To:* Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com *Sent:* Sunday, February 15, 2009 6:15 AM *Subject:* [Repeater-Builder] Re: Help with intermod between repeaters. Thanks to all for your replies. Joe M wrote You need to reject the opposite TX on each repeater. Your BP filters were set wrong. You rejected the RX on the TX side - something the duplexer should be doing already. You need to install them in the repeater and reject the other TX. IOW, install a filter in the .16 repeater and notch the .36 TX. A good duplexer should do this as well, but many don't. Joe that's what I thought I did. Maybe I did not make myself clear. I put a BPBR cavity rejecting 146.76 and passing 147.36 between the repeater transmitter and the duplexer at the 147.36 repeater. This is where I was surprised that the mixing got worse. If I put the cavity in the wrong place let me know. Eric Lemmon WB6FLY wrote The first question that enters my mind is, were both Micor stations originally built as repeaters, with the extra filters and shielding plates,or are one or both base stations that have been converted to repeaters? I built our repeater. It's the 146.76 machine. It was originally a pager TX. All shielding and the lo pass TX filter is in place. I have looked at it with a spectrum analyzer and see no other signal than 146.76. I have no idea as to what the other repeater was made from. I will take a second look at their TX. The next time I go down there I plan to take a 50 watt radio and connect it to their duplexer to try to eliminate or prove their PA has
[Repeater-Builder] Re: Help with intermod between repeaters.
The 600 kc thing also works well with FM stations, in our case 89.3 and 89.9. The mixing here was occurring at guy points of the tower. When I insulated the turnbuckle safety cable (the one they weave through the turnbuckle centers) from the turnbuckles, the intermod went away. Laryn K8TVZ
