Our RPi controlled radio has an rf spectrum so wide that it bleeds over in my Yeasu (150 feet between antennas) when I'm working a distant repeater that is more that 200 kHz away from our tx freq. Any suggestions where I can look for info on how to deal with this? Our duplexer is the notch type. Thanks, Bob k6ecm 73 Sent from my iPhone
Bleeds over as in desensitizes the receivers or you can actually hear audio? Most modern receiver front-ends have minimal filtering, just a wide pass-band filter and the IF filters which reject the adjacent channels more then channels further off frequency. If you have more than -30 dBm showing up on any antenna regardless of frequency spacing it'll probably cause problems. 150 ft is only ~45 dB of isolation, so if you're transmitting with +45 dBm (32W) less 2 dB of duplexer loss, less 2.5 for cable loss plus 3 dB for repeater antenna, less 45 dB of isolation plus 3 dB for rx antenna gives about +1.5 dBm which is definitely going to mess up a receiver unless more filtering is used. You can play with filters to see what works, but I suspect you'll need two notch filters to get that down to something that doesn't effect your receiver. You need to hook the system to a service analyzer and see if it's actually over modulating, it's doubtful unless you've injected audio after any limiter circuits. Running the math it's probably front-end overload, you'd be best to notch out the transmitter on the effected receivers, you may have to put a pass filter (and/or notch filter) on the transmitter too to remove some sideband noise as well, maybe not if it's a clean transmitter. It's usually a good idea to have balanced reject filtering on both your transmitter and receiver. Jesse On Thu, Oct 12, 2017 at 1:13 PM, Bob Pyke <k6ecm1@gmail.com> wrote:
Our RPi controlled radio has an rf spectrum so wide that it bleeds over in my Yeasu (150 feet between antennas) when I'm working a distant repeater that is more that 200 kHz away from our tx freq. Any suggestions where I can look for info on how to deal with this? Our duplexer is the notch type.
Thanks, Bob k6ecm 73 Sent from my iPhone _______________________________________________ App_rpt-users mailing list App_rpt-users@lists.allstarlink.org http://lists.allstarlink.org/cgi-bin/mailman/listinfo/app_rpt-users
To unsubscribe from this list please visit http://lists.allstarlink.org/ cgi-bin/mailman/listinfo/app_rpt-users and scroll down to the bottom of the page. Enter your email address and press the "Unsubscribe or edit options button" You do not need a password to unsubscribe, you can do it via email confirmation. If you have trouble unsubscribing, please send a message to the list detailing the problem.
I'm guessing 75-100 watts on the repeater PA. I can hear intelligible audio (sounds like it is in the bottom of a well) when listening to the other repeater, 240 kHz separation, on my Yeasu. I'm sure the modulation is correct for GE, established with the Allstar setup, but can check with my service monitor. I looked at it on my SDR receiver, and it looks like a lot of rf drive... perhaps just too close at about 150 ft. Thanks, Bob k6ecm 73 Sent from my iPhone
On Oct 12, 2017, at 1:40 PM, Jesse Lloyd <ve7lyd@gmail.com> wrote:
Bleeds over as in desensitizes the receivers or you can actually hear audio?
Most modern receiver front-ends have minimal filtering, just a wide pass-band filter and the IF filters which reject the adjacent channels more then channels further off frequency. If you have more than -30 dBm showing up on any antenna regardless of frequency spacing it'll probably cause problems. 150 ft is only ~45 dB of isolation, so if you're transmitting with +45 dBm (32W) less 2 dB of duplexer loss, less 2.5 for cable loss plus 3 dB for repeater antenna, less 45 dB of isolation plus 3 dB for rx antenna gives about +1.5 dBm which is definitely going to mess up a receiver unless more filtering is used. You can play with filters to see what works, but I suspect you'll need two notch filters to get that down to something that doesn't effect your receiver.
You need to hook the system to a service analyzer and see if it's actually over modulating, it's doubtful unless you've injected audio after any limiter circuits. Running the math it's probably front-end overload, you'd be best to notch out the transmitter on the effected receivers, you may have to put a pass filter (and/or notch filter) on the transmitter too to remove some sideband noise as well, maybe not if it's a clean transmitter. It's usually a good idea to have balanced reject filtering on both your transmitter and receiver.
Jesse
On Thu, Oct 12, 2017 at 1:13 PM, Bob Pyke <k6ecm1@gmail.com> wrote: Our RPi controlled radio has an rf spectrum so wide that it bleeds over in my Yeasu (150 feet between antennas) when I'm working a distant repeater that is more that 200 kHz away from our tx freq. Any suggestions where I can look for info on how to deal with this? Our duplexer is the notch type.
Thanks, Bob k6ecm 73 Sent from my iPhone _______________________________________________ App_rpt-users mailing list App_rpt-users@lists.allstarlink.org http://lists.allstarlink.org/cgi-bin/mailman/listinfo/app_rpt-users
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Ya so if you put a bandpass filter on it, set to 3.2 dB insertion loss you'll get about 22 dB of reject 250 Khz off. If you use two cans set each to 1.1 dB insertion loss each (totaling 2.2 dB) you'll see about 27 dB of reject. You could also put a notch filter on it for that one receive frequency, but you should check first to make sure you aren't getting into other gear at the site (if there is any). At 250 KHz I don't think you'd be able to take a duplexer notch / pass can and tune it to get any significant rejection. Sinclair says the Q201 (6 can duplexer) min freq spacing is 300 KHz. You'd might be able to get 30 dB out of 3 notch/pass cans series'd together, not sure. To get an additional 30 dB of isolation (totaling 70 dB) between the antennas you'll need to space them 3000 ft apart. http://www.repeater-builder.com/antenna/images/horizsep.jpg Vertical separation is better, you need about 100 ft to get 70 dB, maybe a little more. http://www.repeater-builder.com/antenna/images/vertsep.jpg +49 dBm (79W) less 2 dB of duplexer loss, less 2.5 for cable loss plus 3 dB for repeater antenna, less 70 dB of isolation plus 3 dB for rx antenna gives about -19.5 dBm. This probably still isn't enough, you'll probably still see some desense, but might be good enough to work, it'll just make it a little deaf. Really you need to get it further then 240 Khz off freq. then you can get away with only one or two extra cans. Jesse On Thu, Oct 12, 2017 at 5:35 PM, Bob Pyke <k6ecm1@gmail.com> wrote:
I'm guessing 75-100 watts on the repeater PA. I can hear intelligible audio (sounds like it is in the bottom of a well) when listening to the other repeater, 240 kHz separation, on my Yeasu. I'm sure the modulation is correct for GE, established with the Allstar setup, but can check with my service monitor. I looked at it on my SDR receiver, and it looks like a lot of rf drive... perhaps just too close at about 150 ft.
Thanks, Bob k6ecm 73 Sent from my iPhone
On Oct 12, 2017, at 1:40 PM, Jesse Lloyd <ve7lyd@gmail.com> wrote:
Bleeds over as in desensitizes the receivers or you can actually hear audio?
Most modern receiver front-ends have minimal filtering, just a wide pass-band filter and the IF filters which reject the adjacent channels more then channels further off frequency. If you have more than -30 dBm showing up on any antenna regardless of frequency spacing it'll probably cause problems. 150 ft is only ~45 dB of isolation, so if you're transmitting with +45 dBm (32W) less 2 dB of duplexer loss, less 2.5 for cable loss plus 3 dB for repeater antenna, less 45 dB of isolation plus 3 dB for rx antenna gives about +1.5 dBm which is definitely going to mess up a receiver unless more filtering is used. You can play with filters to see what works, but I suspect you'll need two notch filters to get that down to something that doesn't effect your receiver.
You need to hook the system to a service analyzer and see if it's actually over modulating, it's doubtful unless you've injected audio after any limiter circuits. Running the math it's probably front-end overload, you'd be best to notch out the transmitter on the effected receivers, you may have to put a pass filter (and/or notch filter) on the transmitter too to remove some sideband noise as well, maybe not if it's a clean transmitter. It's usually a good idea to have balanced reject filtering on both your transmitter and receiver.
Jesse
On Thu, Oct 12, 2017 at 1:13 PM, Bob Pyke <k6ecm1@gmail.com> wrote:
Our RPi controlled radio has an rf spectrum so wide that it bleeds over in my Yeasu (150 feet between antennas) when I'm working a distant repeater that is more that 200 kHz away from our tx freq. Any suggestions where I can look for info on how to deal with this? Our duplexer is the notch type.
Thanks, Bob k6ecm 73 Sent from my iPhone _______________________________________________ App_rpt-users mailing list App_rpt-users@lists.allstarlink.org http://lists.allstarlink.org/cgi-bin/mailman/listinfo/app_rpt-users
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I'd be surprised that your Yaesu can deal with that strong a signal within the passband of its receiver front end. At best, it is 4 MHz wide, and probably no more that 6 dB down at two to three times that. A test to try is have the nearby repeater key up, the open the squelch on the Yaesu. My guess is the S-meter will show a "signal", possibly near full scale. I also expect the open squelch noise level to drop. This test is done without the distant repeater keyed. There will be zero amount of filtering applied to the nearby repeater transmitter that affects the issue because the problem is the RF coming into the Yaesu itself on the repeater's actual frequency. You can put a (several) bandpass cavity in front of the Yaesu, but then you wouldn't be able to transmit to the distant repeater as the bandpass cavity would significantly attenuate your transmitter. You could also install a notch filter in front of the Yaesu tuned to notch the local repeater frequency. A single notch cavity may not be enough. This will allow you to transmit to the distant repeater. However, the notch from a single cavity is likely to be wide enough to reduce the sensitivity some of the Yaesu at 200 KHz. My analogy to folks is that it's like shining a bright flashlight in one eye while trying to see a candle at one mile. Pretty impossible to overcome the overload. tnx Mike / W5JR Alpharetta GA sent via my HP95LX
On Oct 12, 2017, at 8:16 PM, Jesse Lloyd <ve7lyd@gmail.com> wrote:
Ya so if you put a bandpass filter on it, set to 3.2 dB insertion loss you'll get about 22 dB of reject 250 Khz off. If you use two cans set each to 1.1 dB insertion loss each (totaling 2.2 dB) you'll see about 27 dB of reject. You could also put a notch filter on it for that one receive frequency, but you should check first to make sure you aren't getting into other gear at the site (if there is any). At 250 KHz I don't think you'd be able to take a duplexer notch / pass can and tune it to get any significant rejection. Sinclair says the Q201 (6 can duplexer) min freq spacing is 300 KHz. You'd might be able to get 30 dB out of 3 notch/pass cans series'd together, not sure.
To get an additional 30 dB of isolation (totaling 70 dB) between the antennas you'll need to space them 3000 ft apart. http://www.repeater-builder.com/antenna/images/horizsep.jpg Vertical separation is better, you need about 100 ft to get 70 dB, maybe a little more. http://www.repeater-builder.com/antenna/images/vertsep.jpg
+49 dBm (79W) less 2 dB of duplexer loss, less 2.5 for cable loss plus 3 dB for repeater antenna, less 70 dB of isolation plus 3 dB for rx antenna gives about -19.5 dBm. This probably still isn't enough, you'll probably still see some desense, but might be good enough to work, it'll just make it a little deaf.
Really you need to get it further then 240 Khz off freq. then you can get away with only one or two extra cans.
Jesse
On Thu, Oct 12, 2017 at 5:35 PM, Bob Pyke <k6ecm1@gmail.com> wrote: I'm guessing 75-100 watts on the repeater PA. I can hear intelligible audio (sounds like it is in the bottom of a well) when listening to the other repeater, 240 kHz separation, on my Yeasu. I'm sure the modulation is correct for GE, established with the Allstar setup, but can check with my service monitor. I looked at it on my SDR receiver, and it looks like a lot of rf drive... perhaps just too close at about 150 ft.
Thanks, Bob k6ecm 73 Sent from my iPhone
On Oct 12, 2017, at 1:40 PM, Jesse Lloyd <ve7lyd@gmail.com> wrote:
Bleeds over as in desensitizes the receivers or you can actually hear audio?
Most modern receiver front-ends have minimal filtering, just a wide pass-band filter and the IF filters which reject the adjacent channels more then channels further off frequency. If you have more than -30 dBm showing up on any antenna regardless of frequency spacing it'll probably cause problems. 150 ft is only ~45 dB of isolation, so if you're transmitting with +45 dBm (32W) less 2 dB of duplexer loss, less 2.5 for cable loss plus 3 dB for repeater antenna, less 45 dB of isolation plus 3 dB for rx antenna gives about +1.5 dBm which is definitely going to mess up a receiver unless more filtering is used. You can play with filters to see what works, but I suspect you'll need two notch filters to get that down to something that doesn't effect your receiver.
You need to hook the system to a service analyzer and see if it's actually over modulating, it's doubtful unless you've injected audio after any limiter circuits. Running the math it's probably front-end overload, you'd be best to notch out the transmitter on the effected receivers, you may have to put a pass filter (and/or notch filter) on the transmitter too to remove some sideband noise as well, maybe not if it's a clean transmitter. It's usually a good idea to have balanced reject filtering on both your transmitter and receiver.
Jesse
On Thu, Oct 12, 2017 at 1:13 PM, Bob Pyke <k6ecm1@gmail.com> wrote: Our RPi controlled radio has an rf spectrum so wide that it bleeds over in my Yeasu (150 feet between antennas) when I'm working a distant repeater that is more that 200 kHz away from our tx freq. Any suggestions where I can look for info on how to deal with this? Our duplexer is the notch type.
Thanks, Bob k6ecm 73 Sent from my iPhone _______________________________________________ App_rpt-users mailing list App_rpt-users@lists.allstarlink.org http://lists.allstarlink.org/cgi-bin/mailman/listinfo/app_rpt-users
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Makes sense. I'll try using the receiver at varying distances from the MASTR II. Thanks, Bob k6ecm Sent from my iPhone
On Oct 12, 2017, at 7:39 PM, Mike - W5JR <w5jr.lists@gmail.com> wrote:
I'd be surprised that your Yaesu can deal with that strong a signal within the passband of its receiver front end. At best, it is 4 MHz wide, and probably no more that 6 dB down at two to three times that.
A test to try is have the nearby repeater key up, the open the squelch on the Yaesu. My guess is the S-meter will show a "signal", possibly near full scale. I also expect the open squelch noise level to drop. This test is done without the distant repeater keyed.
There will be zero amount of filtering applied to the nearby repeater transmitter that affects the issue because the problem is the RF coming into the Yaesu itself on the repeater's actual frequency. You can put a (several) bandpass cavity in front of the Yaesu, but then you wouldn't be able to transmit to the distant repeater as the bandpass cavity would significantly attenuate your transmitter.
You could also install a notch filter in front of the Yaesu tuned to notch the local repeater frequency. A single notch cavity may not be enough. This will allow you to transmit to the distant repeater. However, the notch from a single cavity is likely to be wide enough to reduce the sensitivity some of the Yaesu at 200 KHz.
My analogy to folks is that it's like shining a bright flashlight in one eye while trying to see a candle at one mile. Pretty impossible to overcome the overload.
tnx Mike / W5JR Alpharetta GA
sent via my HP95LX
On Oct 12, 2017, at 8:16 PM, Jesse Lloyd <ve7lyd@gmail.com> wrote:
Ya so if you put a bandpass filter on it, set to 3.2 dB insertion loss you'll get about 22 dB of reject 250 Khz off. If you use two cans set each to 1.1 dB insertion loss each (totaling 2.2 dB) you'll see about 27 dB of reject. You could also put a notch filter on it for that one receive frequency, but you should check first to make sure you aren't getting into other gear at the site (if there is any). At 250 KHz I don't think you'd be able to take a duplexer notch / pass can and tune it to get any significant rejection. Sinclair says the Q201 (6 can duplexer) min freq spacing is 300 KHz. You'd might be able to get 30 dB out of 3 notch/pass cans series'd together, not sure.
To get an additional 30 dB of isolation (totaling 70 dB) between the antennas you'll need to space them 3000 ft apart. http://www.repeater-builder.com/antenna/images/horizsep.jpg Vertical separation is better, you need about 100 ft to get 70 dB, maybe a little more. http://www.repeater-builder.com/antenna/images/vertsep.jpg
+49 dBm (79W) less 2 dB of duplexer loss, less 2.5 for cable loss plus 3 dB for repeater antenna, less 70 dB of isolation plus 3 dB for rx antenna gives about -19.5 dBm. This probably still isn't enough, you'll probably still see some desense, but might be good enough to work, it'll just make it a little deaf.
Really you need to get it further then 240 Khz off freq. then you can get away with only one or two extra cans.
Jesse
On Thu, Oct 12, 2017 at 5:35 PM, Bob Pyke <k6ecm1@gmail.com> wrote: I'm guessing 75-100 watts on the repeater PA. I can hear intelligible audio (sounds like it is in the bottom of a well) when listening to the other repeater, 240 kHz separation, on my Yeasu. I'm sure the modulation is correct for GE, established with the Allstar setup, but can check with my service monitor. I looked at it on my SDR receiver, and it looks like a lot of rf drive... perhaps just too close at about 150 ft.
Thanks, Bob k6ecm 73 Sent from my iPhone
On Oct 12, 2017, at 1:40 PM, Jesse Lloyd <ve7lyd@gmail.com> wrote:
Bleeds over as in desensitizes the receivers or you can actually hear audio?
Most modern receiver front-ends have minimal filtering, just a wide pass-band filter and the IF filters which reject the adjacent channels more then channels further off frequency. If you have more than -30 dBm showing up on any antenna regardless of frequency spacing it'll probably cause problems. 150 ft is only ~45 dB of isolation, so if you're transmitting with +45 dBm (32W) less 2 dB of duplexer loss, less 2.5 for cable loss plus 3 dB for repeater antenna, less 45 dB of isolation plus 3 dB for rx antenna gives about +1.5 dBm which is definitely going to mess up a receiver unless more filtering is used. You can play with filters to see what works, but I suspect you'll need two notch filters to get that down to something that doesn't effect your receiver.
You need to hook the system to a service analyzer and see if it's actually over modulating, it's doubtful unless you've injected audio after any limiter circuits. Running the math it's probably front-end overload, you'd be best to notch out the transmitter on the effected receivers, you may have to put a pass filter (and/or notch filter) on the transmitter too to remove some sideband noise as well, maybe not if it's a clean transmitter. It's usually a good idea to have balanced reject filtering on both your transmitter and receiver.
Jesse
On Thu, Oct 12, 2017 at 1:13 PM, Bob Pyke <k6ecm1@gmail.com> wrote: Our RPi controlled radio has an rf spectrum so wide that it bleeds over in my Yeasu (150 feet between antennas) when I'm working a distant repeater that is more that 200 kHz away from our tx freq. Any suggestions where I can look for info on how to deal with this? Our duplexer is the notch type.
Thanks, Bob k6ecm 73 Sent from my iPhone _______________________________________________ App_rpt-users mailing list App_rpt-users@lists.allstarlink.org http://lists.allstarlink.org/cgi-bin/mailman/listinfo/app_rpt-users
To unsubscribe from this list please visit http://lists.allstarlink.org/cgi-bin/mailman/listinfo/app_rpt-users and scroll down to the bottom of the page. Enter your email address and press the "Unsubscribe or edit options button" You do not need a password to unsubscribe, you can do it via email confirmation. If you have trouble unsubscribing, please send a message to the list detailing the problem.
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Understand. Good info. Learning a lot here from all. Thanks, Bob Sent from my iPhone
On Oct 12, 2017, at 6:16 PM, Jesse Lloyd <ve7lyd@gmail.com> wrote:
Ya so if you put a bandpass filter on it, set to 3.2 dB insertion loss you'll get about 22 dB of reject 250 Khz off. If you use two cans set each to 1.1 dB insertion loss each (totaling 2.2 dB) you'll see about 27 dB of reject. You could also put a notch filter on it for that one receive frequency, but you should check first to make sure you aren't getting into other gear at the site (if there is any). At 250 KHz I don't think you'd be able to take a duplexer notch / pass can and tune it to get any significant rejection. Sinclair says the Q201 (6 can duplexer) min freq spacing is 300 KHz. You'd might be able to get 30 dB out of 3 notch/pass cans series'd together, not sure.
To get an additional 30 dB of isolation (totaling 70 dB) between the antennas you'll need to space them 3000 ft apart. http://www.repeater-builder.com/antenna/images/horizsep.jpg Vertical separation is better, you need about 100 ft to get 70 dB, maybe a little more. http://www.repeater-builder.com/antenna/images/vertsep.jpg
+49 dBm (79W) less 2 dB of duplexer loss, less 2.5 for cable loss plus 3 dB for repeater antenna, less 70 dB of isolation plus 3 dB for rx antenna gives about -19.5 dBm. This probably still isn't enough, you'll probably still see some desense, but might be good enough to work, it'll just make it a little deaf.
Really you need to get it further then 240 Khz off freq. then you can get away with only one or two extra cans.
Jesse
On Thu, Oct 12, 2017 at 5:35 PM, Bob Pyke <k6ecm1@gmail.com> wrote: I'm guessing 75-100 watts on the repeater PA. I can hear intelligible audio (sounds like it is in the bottom of a well) when listening to the other repeater, 240 kHz separation, on my Yeasu. I'm sure the modulation is correct for GE, established with the Allstar setup, but can check with my service monitor. I looked at it on my SDR receiver, and it looks like a lot of rf drive... perhaps just too close at about 150 ft.
Thanks, Bob k6ecm 73 Sent from my iPhone
On Oct 12, 2017, at 1:40 PM, Jesse Lloyd <ve7lyd@gmail.com> wrote:
Bleeds over as in desensitizes the receivers or you can actually hear audio?
Most modern receiver front-ends have minimal filtering, just a wide pass-band filter and the IF filters which reject the adjacent channels more then channels further off frequency. If you have more than -30 dBm showing up on any antenna regardless of frequency spacing it'll probably cause problems. 150 ft is only ~45 dB of isolation, so if you're transmitting with +45 dBm (32W) less 2 dB of duplexer loss, less 2.5 for cable loss plus 3 dB for repeater antenna, less 45 dB of isolation plus 3 dB for rx antenna gives about +1.5 dBm which is definitely going to mess up a receiver unless more filtering is used. You can play with filters to see what works, but I suspect you'll need two notch filters to get that down to something that doesn't effect your receiver.
You need to hook the system to a service analyzer and see if it's actually over modulating, it's doubtful unless you've injected audio after any limiter circuits. Running the math it's probably front-end overload, you'd be best to notch out the transmitter on the effected receivers, you may have to put a pass filter (and/or notch filter) on the transmitter too to remove some sideband noise as well, maybe not if it's a clean transmitter. It's usually a good idea to have balanced reject filtering on both your transmitter and receiver.
Jesse
On Thu, Oct 12, 2017 at 1:13 PM, Bob Pyke <k6ecm1@gmail.com> wrote: Our RPi controlled radio has an rf spectrum so wide that it bleeds over in my Yeasu (150 feet between antennas) when I'm working a distant repeater that is more that 200 kHz away from our tx freq. Any suggestions where I can look for info on how to deal with this? Our duplexer is the notch type.
Thanks, Bob k6ecm 73 Sent from my iPhone _______________________________________________ App_rpt-users mailing list App_rpt-users@lists.allstarlink.org http://lists.allstarlink.org/cgi-bin/mailman/listinfo/app_rpt-users
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Bob, I caught up on this thread, this morning. Is the Mastr II VHF HI or UHF? If VHF HIGH, do you know if it is a PLL-type direct FM exciter or the earlier phasing-type, crystal multiplier variety? Also, what type of sound device are you using for interfacing the RPi--a URI, RIM or homebrew board? And, what type of Yaesu radio? What types of antennas?? And, any differences in vertical height between the antennas? When you're hearing the Mastr II 200+ khz from the TX frequency, is it only at certain, distinct spots or completely broadband? 73, David KB4FXC On Thu, 12 Oct 2017, Bob Pyke wrote:
Understand. Good info. Learning a lot here from all.
Thanks, Bob
Sent from my iPhone
On Oct 12, 2017, at 6:16 PM, Jesse Lloyd <ve7lyd@gmail.com> wrote:
Ya so if you put a bandpass filter on it, set to 3.2 dB insertion loss you'll get about 22 dB of reject 250 Khz off. If you use two cans set each to 1.1 dB insertion loss each (totaling 2.2 dB) you'll see about 27 dB of reject. You could also put a notch filter on it for that one receive frequency, but you should check first to make sure you aren't getting into other gear at the site (if there is any). At 250 KHz I don't think you'd be able to take a duplexer notch / pass can and tune it to get any significant rejection. Sinclair says the Q201 (6 can duplexer) min freq spacing is 300 KHz. You'd might be able to get 30 dB out of 3 notch/pass cans series'd together, not sure.
To get an additional 30 dB of isolation (totaling 70 dB) between the antennas you'll need to space them 3000 ft apart. http://www.repeater-builder.com/antenna/images/horizsep.jpg Vertical separation is better, you need about 100 ft to get 70 dB, maybe a little more. http://www.repeater-builder.com/antenna/images/vertsep.jpg
+49 dBm (79W) less 2 dB of duplexer loss, less 2.5 for cable loss plus 3 dB for repeater antenna, less 70 dB of isolation plus 3 dB for rx antenna gives about -19.5 dBm. This probably still isn't enough, you'll probably still see some desense, but might be good enough to work, it'll just make it a little deaf.
Really you need to get it further then 240 Khz off freq. then you can get away with only one or two extra cans.
Jesse
On Thu, Oct 12, 2017 at 5:35 PM, Bob Pyke <k6ecm1@gmail.com> wrote: I'm guessing 75-100 watts on the repeater PA. I can hear intelligible audio (sounds like it is in the bottom of a well) when listening to the other repeater, 240 kHz separation, on my Yeasu. I'm sure the modulation is correct for GE, established with the Allstar setup, but can check with my service monitor. I looked at it on my SDR receiver, and it looks like a lot of rf drive... perhaps just too close at about 150 ft.
Thanks, Bob k6ecm 73 Sent from my iPhone
On Oct 12, 2017, at 1:40 PM, Jesse Lloyd <ve7lyd@gmail.com> wrote:
Bleeds over as in desensitizes the receivers or you can actually hear audio?
Most modern receiver front-ends have minimal filtering, just a wide pass-band filter and the IF filters which reject the adjacent channels more then channels further off frequency. If you have more than -30 dBm showing up on any antenna regardless of frequency spacing it'll probably cause problems. 150 ft is only ~45 dB of isolation, so if you're transmitting with +45 dBm (32W) less 2 dB of duplexer loss, less 2.5 for cable loss plus 3 dB for repeater antenna, less 45 dB of isolation plus 3 dB for rx antenna gives about +1.5 dBm which is definitely going to mess up a receiver unless more filtering is used. You can play with filters to see what works, but I suspect you'll need two notch filters to get that down to something that doesn't effect your receiver.
You need to hook the system to a service analyzer and see if it's actually over modulating, it's doubtful unless you've injected audio after any limiter circuits. Running the math it's probably front-end overload, you'd be best to notch out the transmitter on the effected receivers, you may have to put a pass filter (and/or notch filter) on the transmitter too to remove some sideband noise as well, maybe not if it's a clean transmitter. It's usually a good idea to have balanced reject filtering on both your transmitter and receiver.
Jesse
On Thu, Oct 12, 2017 at 1:13 PM, Bob Pyke <k6ecm1@gmail.com> wrote: Our RPi controlled radio has an rf spectrum so wide that it bleeds over in my Yeasu (150 feet between antennas) when I'm working a distant repeater that is more that 200 kHz away from our tx freq. Any suggestions where I can look for info on how to deal with this? Our duplexer is the notch type.
Thanks, Bob k6ecm 73 Sent from my iPhone _______________________________________________ App_rpt-users mailing list App_rpt-users@lists.allstarlink.org http://lists.allstarlink.org/cgi-bin/mailman/listinfo/app_rpt-users
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Thanks David, See responses interspersed below. Sent from iPad Sent from iPad
On Oct 13, 2017, at 4:05 AM, David McGough <kb4fxc@inttek.net> wrote:
Bob,
I caught up on this thread, this morning. Is the Mastr II VHF HI or UHF? If VHF HIGH, do you know if it is a PLL-type direct FM exciter or the earlier phasing-type, crystal multiplier variety? Local repeater is on 147.000, and the distant repeater is on 146.760. It's been awhile since I looked at the schematic, but I believe the latter. We have a Yeasu repeater (DR-1X on analog) offered to us, but I need to find notes on interfacing to Allstar.
Also, what type of sound device are you using for interfacing the RPi--a URI, RIM or homebrew board? URIx
And, what type of Yaesu radio? What types of antennas?? And, any differences in vertical height between the antennas? FT-8900. Antennas are pretty much at co-elevation, about 150 ft apart, both setup as omni-directional (147.000 stacked dipoles, ~9 dbi, Yeasu 5/8 vertical). I just assembled a yagi for the Yeasu, which would point away from the 147.000, but I don't believe it will have enough rejection on the back side.
When you're hearing the Mastr II 200+ khz from the TX frequency, is it only at certain, distinct spots or completely broadband? I've not checked that. When I use my SDR receiver, the 147.000 signal really blooms, which I'd expect even if properly modulated, and being in too high a field strength.
This all came about when I began looking for a quick solution to chicken link the two repeaters to see if folks would want them linked... inexpensive, and easy to do for a short term experiment (Ha!). I'm now expanding my considered solutions; one, a remote repeater already on Allstar owned by a friend, that I help maintain, and the other repeater is rf linked to the 146.760, which is reported to have a microwave link (Ubiquiti) that I may be able to link in an RPi Allstar node on-site (that will take some discussion with the owner). Allstar provides us with the ability to easily disconnect the two systems when necessary, and on a regular basis, for separate events. We (both repeater owner groups) are working to get coverage over a larger mountainous region. Thanks, Bob
73, David KB4FXC
On Thu, 12 Oct 2017, Bob Pyke wrote:
Understand. Good info. Learning a lot here from all.
Thanks, Bob
Sent from my iPhone
On Oct 12, 2017, at 6:16 PM, Jesse Lloyd <ve7lyd@gmail.com> wrote:
Ya so if you put a bandpass filter on it, set to 3.2 dB insertion loss you'll get about 22 dB of reject 250 Khz off. If you use two cans set each to 1.1 dB insertion loss each (totaling 2.2 dB) you'll see about 27 dB of reject. You could also put a notch filter on it for that one receive frequency, but you should check first to make sure you aren't getting into other gear at the site (if there is any). At 250 KHz I don't think you'd be able to take a duplexer notch / pass can and tune it to get any significant rejection. Sinclair says the Q201 (6 can duplexer) min freq spacing is 300 KHz. You'd might be able to get 30 dB out of 3 notch/pass cans series'd together, not sure.
To get an additional 30 dB of isolation (totaling 70 dB) between the antennas you'll need to space them 3000 ft apart. http://www.repeater-builder.com/antenna/images/horizsep.jpg Vertical separation is better, you need about 100 ft to get 70 dB, maybe a little more. http://www.repeater-builder.com/antenna/images/vertsep.jpg
+49 dBm (79W) less 2 dB of duplexer loss, less 2.5 for cable loss plus 3 dB for repeater antenna, less 70 dB of isolation plus 3 dB for rx antenna gives about -19.5 dBm. This probably still isn't enough, you'll probably still see some desense, but might be good enough to work, it'll just make it a little deaf.
Really you need to get it further then 240 Khz off freq. then you can get away with only one or two extra cans.
Jesse
On Thu, Oct 12, 2017 at 5:35 PM, Bob Pyke <k6ecm1@gmail.com> wrote: I'm guessing 75-100 watts on the repeater PA. I can hear intelligible audio (sounds like it is in the bottom of a well) when listening to the other repeater, 240 kHz separation, on my Yeasu. I'm sure the modulation is correct for GE, established with the Allstar setup, but can check with my service monitor. I looked at it on my SDR receiver, and it looks like a lot of rf drive... perhaps just too close at about 150 ft.
Thanks, Bob k6ecm 73 Sent from my iPhone
On Oct 12, 2017, at 1:40 PM, Jesse Lloyd <ve7lyd@gmail.com> wrote:
Bleeds over as in desensitizes the receivers or you can actually hear audio?
Most modern receiver front-ends have minimal filtering, just a wide pass-band filter and the IF filters which reject the adjacent channels more then channels further off frequency. If you have more than -30 dBm showing up on any antenna regardless of frequency spacing it'll probably cause problems. 150 ft is only ~45 dB of isolation, so if you're transmitting with +45 dBm (32W) less 2 dB of duplexer loss, less 2.5 for cable loss plus 3 dB for repeater antenna, less 45 dB of isolation plus 3 dB for rx antenna gives about +1.5 dBm which is definitely going to mess up a receiver unless more filtering is used. You can play with filters to see what works, but I suspect you'll need two notch filters to get that down to something that doesn't effect your receiver.
You need to hook the system to a service analyzer and see if it's actually over modulating, it's doubtful unless you've injected audio after any limiter circuits. Running the math it's probably front-end overload, you'd be best to notch out the transmitter on the effected receivers, you may have to put a pass filter (and/or notch filter) on the transmitter too to remove some sideband noise as well, maybe not if it's a clean transmitter. It's usually a good idea to have balanced reject filtering on both your transmitter and receiver.
Jesse
On Thu, Oct 12, 2017 at 1:13 PM, Bob Pyke <k6ecm1@gmail.com> wrote: Our RPi controlled radio has an rf spectrum so wide that it bleeds over in my Yeasu (150 feet between antennas) when I'm working a distant repeater that is more that 200 kHz away from our tx freq. Any suggestions where I can look for info on how to deal with this? Our duplexer is the notch type.
Thanks, Bob k6ecm 73 Sent from my iPhone _______________________________________________ App_rpt-users mailing list App_rpt-users@lists.allstarlink.org http://lists.allstarlink.org/cgi-bin/mailman/listinfo/app_rpt-users
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Bob, One more question in my barrage: In the 8900 RX, do you hear the carrier from the Mastr II TX even with no modulation? 73, David KB4FXC On Fri, 13 Oct 2017, Bob Pyke wrote:
Thanks David, See responses interspersed below.
Sent from iPad Sent from iPad
On Oct 13, 2017, at 4:05 AM, David McGough <kb4fxc@inttek.net> wrote:
Bob,
I caught up on this thread, this morning. Is the Mastr II VHF HI or UHF? If VHF HIGH, do you know if it is a PLL-type direct FM exciter or the earlier phasing-type, crystal multiplier variety? Local repeater is on 147.000, and the distant repeater is on 146.760. It's been awhile since I looked at the schematic, but I believe the latter. We have a Yeasu repeater (DR-1X on analog) offered to us, but I need to find notes on interfacing to Allstar.
Also, what type of sound device are you using for interfacing the RPi--a URI, RIM or homebrew board? URIx
And, what type of Yaesu radio? What types of antennas?? And, any differences in vertical height between the antennas? FT-8900. Antennas are pretty much at co-elevation, about 150 ft apart, both setup as omni-directional (147.000 stacked dipoles, ~9 dbi, Yeasu 5/8 vertical). I just assembled a yagi for the Yeasu, which would point away from the 147.000, but I don't believe it will have enough rejection on the back side.
When you're hearing the Mastr II 200+ khz from the TX frequency, is it only at certain, distinct spots or completely broadband? I've not checked that. When I use my SDR receiver, the 147.000 signal really blooms, which I'd expect even if properly modulated, and being in too high a field strength.
This all came about when I began looking for a quick solution to chicken link the two repeaters to see if folks would want them linked... inexpensive, and easy to do for a short term experiment (Ha!). I'm now expanding my considered solutions; one, a remote repeater already on Allstar owned by a friend, that I help maintain, and the other repeater is rf linked to the 146.760, which is reported to have a microwave link (Ubiquiti) that I may be able to link in an RPi Allstar node on-site (that will take some discussion with the owner). Allstar provides us with the ability to easily disconnect the two systems when necessary, and on a regular basis, for separate events. We (both repeater owner groups) are working to get coverage over a larger mountainous region. Thanks, Bob
73, David KB4FXC
On Thu, 12 Oct 2017, Bob Pyke wrote:
Understand. Good info. Learning a lot here from all.
Thanks, Bob
Sent from my iPhone
On Oct 12, 2017, at 6:16 PM, Jesse Lloyd <ve7lyd@gmail.com> wrote:
Ya so if you put a bandpass filter on it, set to 3.2 dB insertion loss you'll get about 22 dB of reject 250 Khz off. If you use two cans set each to 1.1 dB insertion loss each (totaling 2.2 dB) you'll see about 27 dB of reject. You could also put a notch filter on it for that one receive frequency, but you should check first to make sure you aren't getting into other gear at the site (if there is any). At 250 KHz I don't think you'd be able to take a duplexer notch / pass can and tune it to get any significant rejection. Sinclair says the Q201 (6 can duplexer) min freq spacing is 300 KHz. You'd might be able to get 30 dB out of 3 notch/pass cans series'd together, not sure.
To get an additional 30 dB of isolation (totaling 70 dB) between the antennas you'll need to space them 3000 ft apart. http://www.repeater-builder.com/antenna/images/horizsep.jpg Vertical separation is better, you need about 100 ft to get 70 dB, maybe a little more. http://www.repeater-builder.com/antenna/images/vertsep.jpg
+49 dBm (79W) less 2 dB of duplexer loss, less 2.5 for cable loss plus 3 dB for repeater antenna, less 70 dB of isolation plus 3 dB for rx antenna gives about -19.5 dBm. This probably still isn't enough, you'll probably still see some desense, but might be good enough to work, it'll just make it a little deaf.
Really you need to get it further then 240 Khz off freq. then you can get away with only one or two extra cans.
Jesse
On Thu, Oct 12, 2017 at 5:35 PM, Bob Pyke <k6ecm1@gmail.com> wrote: I'm guessing 75-100 watts on the repeater PA. I can hear intelligible audio (sounds like it is in the bottom of a well) when listening to the other repeater, 240 kHz separation, on my Yeasu. I'm sure the modulation is correct for GE, established with the Allstar setup, but can check with my service monitor. I looked at it on my SDR receiver, and it looks like a lot of rf drive... perhaps just too close at about 150 ft.
Thanks, Bob k6ecm 73 Sent from my iPhone
On Oct 12, 2017, at 1:40 PM, Jesse Lloyd <ve7lyd@gmail.com> wrote:
Bleeds over as in desensitizes the receivers or you can actually hear audio?
Most modern receiver front-ends have minimal filtering, just a wide pass-band filter and the IF filters which reject the adjacent channels more then channels further off frequency. If you have more than -30 dBm showing up on any antenna regardless of frequency spacing it'll probably cause problems. 150 ft is only ~45 dB of isolation, so if you're transmitting with +45 dBm (32W) less 2 dB of duplexer loss, less 2.5 for cable loss plus 3 dB for repeater antenna, less 45 dB of isolation plus 3 dB for rx antenna gives about +1.5 dBm which is definitely going to mess up a receiver unless more filtering is used. You can play with filters to see what works, but I suspect you'll need two notch filters to get that down to something that doesn't effect your receiver.
You need to hook the system to a service analyzer and see if it's actually over modulating, it's doubtful unless you've injected audio after any limiter circuits. Running the math it's probably front-end overload, you'd be best to notch out the transmitter on the effected receivers, you may have to put a pass filter (and/or notch filter) on the transmitter too to remove some sideband noise as well, maybe not if it's a clean transmitter. It's usually a good idea to have balanced reject filtering on both your transmitter and receiver.
Jesse
On Thu, Oct 12, 2017 at 1:13 PM, Bob Pyke <k6ecm1@gmail.com> wrote: Our RPi controlled radio has an rf spectrum so wide that it bleeds over in my Yeasu (150 feet between antennas) when I'm working a distant repeater that is more that 200 kHz away from our tx freq. Any suggestions where I can look for info on how to deal with this? Our duplexer is the notch type.
Thanks, Bob k6ecm 73 Sent from my iPhone _______________________________________________ App_rpt-users mailing list App_rpt-users@lists.allstarlink.org http://lists.allstarlink.org/cgi-bin/mailman/listinfo/app_rpt-users
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Not sure if I would recognize it. The audio is understandable, and sounds echoy; bottom of the well like. I'll try it again. Sent from iPad
On Oct 14, 2017, at 4:38 AM, David McGough <kb4fxc@inttek.net> wrote:
Bob,
One more question in my barrage: In the 8900 RX, do you hear the carrier from the Mastr II TX even with no modulation?
73, David KB4FXC
On Fri, 13 Oct 2017, Bob Pyke wrote:
Thanks David, See responses interspersed below.
Sent from iPad
Sent from iPad
On Oct 13, 2017, at 4:05 AM, David McGough <kb4fxc@inttek.net> wrote:
Bob,
I caught up on this thread, this morning. Is the Mastr II VHF HI or UHF? If VHF HIGH, do you know if it is a PLL-type direct FM exciter or the earlier phasing-type, crystal multiplier variety? Local repeater is on 147.000, and the distant repeater is on 146.760. It's been awhile since I looked at the schematic, but I believe the latter. We have a Yeasu repeater (DR-1X on analog) offered to us, but I need to find notes on interfacing to Allstar.
Also, what type of sound device are you using for interfacing the RPi--a URI, RIM or homebrew board? URIx
And, what type of Yaesu radio? What types of antennas?? And, any differences in vertical height between the antennas? FT-8900. Antennas are pretty much at co-elevation, about 150 ft apart, both setup as omni-directional (147.000 stacked dipoles, ~9 dbi, Yeasu 5/8 vertical). I just assembled a yagi for the Yeasu, which would point away from the 147.000, but I don't believe it will have enough rejection on the back side.
When you're hearing the Mastr II 200+ khz from the TX frequency, is it only at certain, distinct spots or completely broadband? I've not checked that. When I use my SDR receiver, the 147.000 signal really blooms, which I'd expect even if properly modulated, and being in too high a field strength.
This all came about when I began looking for a quick solution to chicken link the two repeaters to see if folks would want them linked... inexpensive, and easy to do for a short term experiment (Ha!). I'm now expanding my considered solutions; one, a remote repeater already on Allstar owned by a friend, that I help maintain, and the other repeater is rf linked to the 146.760, which is reported to have a microwave link (Ubiquiti) that I may be able to link in an RPi Allstar node on-site (that will take some discussion with the owner). Allstar provides us with the ability to easily disconnect the two systems when necessary, and on a regular basis, for separate events. We (both repeater owner groups) are working to get coverage over a larger mountainous region.
Thanks, Bob
73, David KB4FXC
On Thu, 12 Oct 2017, Bob Pyke wrote:
Understand. Good info. Learning a lot here from all.
Thanks, Bob
Sent from my iPhone
On Oct 12, 2017, at 6:16 PM, Jesse Lloyd <ve7lyd@gmail.com> wrote:
Ya so if you put a bandpass filter on it, set to 3.2 dB insertion loss you'll get about 22 dB of reject 250 Khz off. If you use two cans set each to 1.1 dB insertion loss each (totaling 2.2 dB) you'll see about 27 dB of reject. You could also put a notch filter on it for that one receive frequency, but you should check first to make sure you aren't getting into other gear at the site (if there is any). At 250 KHz I don't think you'd be able to take a duplexer notch / pass can and tune it to get any significant rejection. Sinclair says the Q201 (6 can duplexer) min freq spacing is 300 KHz. You'd might be able to get 30 dB out of 3 notch/pass cans series'd together, not sure.
To get an additional 30 dB of isolation (totaling 70 dB) between the antennas you'll need to space them 3000 ft apart. http://www.repeater-builder.com/antenna/images/horizsep.jpg Vertical separation is better, you need about 100 ft to get 70 dB, maybe a little more. http://www.repeater-builder.com/antenna/images/vertsep.jpg
+49 dBm (79W) less 2 dB of duplexer loss, less 2.5 for cable loss plus 3 dB for repeater antenna, less 70 dB of isolation plus 3 dB for rx antenna gives about -19.5 dBm. This probably still isn't enough, you'll probably still see some desense, but might be good enough to work, it'll just make it a little deaf.
Really you need to get it further then 240 Khz off freq. then you can get away with only one or two extra cans.
Jesse
On Thu, Oct 12, 2017 at 5:35 PM, Bob Pyke <k6ecm1@gmail.com> wrote: I'm guessing 75-100 watts on the repeater PA. I can hear intelligible audio (sounds like it is in the bottom of a well) when listening to the other repeater, 240 kHz separation, on my Yeasu. I'm sure the modulation is correct for GE, established with the Allstar setup, but can check with my service monitor. I looked at it on my SDR receiver, and it looks like a lot of rf drive... perhaps just too close at about 150 ft.
Thanks, Bob k6ecm 73 Sent from my iPhone
On Oct 12, 2017, at 1:40 PM, Jesse Lloyd <ve7lyd@gmail.com> wrote:
Bleeds over as in desensitizes the receivers or you can actually hear audio?
Most modern receiver front-ends have minimal filtering, just a wide pass-band filter and the IF filters which reject the adjacent channels more then channels further off frequency. If you have more than -30 dBm showing up on any antenna regardless of frequency spacing it'll probably cause problems. 150 ft is only ~45 dB of isolation, so if you're transmitting with +45 dBm (32W) less 2 dB of duplexer loss, less 2.5 for cable loss plus 3 dB for repeater antenna, less 45 dB of isolation plus 3 dB for rx antenna gives about +1.5 dBm which is definitely going to mess up a receiver unless more filtering is used. You can play with filters to see what works, but I suspect you'll need two notch filters to get that down to something that doesn't effect your receiver.
You need to hook the system to a service analyzer and see if it's actually over modulating, it's doubtful unless you've injected audio after any limiter circuits. Running the math it's probably front-end overload, you'd be best to notch out the transmitter on the effected receivers, you may have to put a pass filter (and/or notch filter) on the transmitter too to remove some sideband noise as well, maybe not if it's a clean transmitter. It's usually a good idea to have balanced reject filtering on both your transmitter and receiver.
Jesse
On Thu, Oct 12, 2017 at 1:13 PM, Bob Pyke <k6ecm1@gmail.com> wrote: Our RPi controlled radio has an rf spectrum so wide that it bleeds over in my Yeasu (150 feet between antennas) when I'm working a distant repeater that is more that 200 kHz away from our tx freq. Any suggestions where I can look for info on how to deal with this? Our duplexer is the notch type.
Thanks, Bob k6ecm 73 Sent from my iPhone _______________________________________________ App_rpt-users mailing list App_rpt-users@lists.allstarlink.org http://lists.allstarlink.org/cgi-bin/mailman/listinfo/app_rpt-users
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participants (4)
-
Bob Pyke -
David McGough -
Jesse Lloyd -
Mike - W5JR