Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer
Mike WA6ILQ wrote: > I like the idea but I'd use a parked mobile instead. HT's are hand held > and can > be moved which will change the signal level, plus they pull 3/4 to 1amp from > the batteries and can suck them down, which also changes the signal level. > The use of a parked mobile - set to the lowest power level it can do - > eliminates > both factors from the equation. > > Mike WA6ILQ > I use my Kenwood G-71 at what they call 'extra-low' power-about 60-75mW, with no antenna. At that power level, reflected power isn't likely to do much damage, since there's probably that much or more with the duck on high power. But yes, you do have a problem with movement with a handheld. -- Jim Barbour WD8CHL Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer
Will give that a try tomorrow and see if it is the same and take it from there. I'm almost betting it is the Handhelds with the elevated pl tone output. Going to have to give another stab at making an iso tee to work with. Thanks for the input. Will let you know how it comes out. Mathew > You want the user to be a bit noisy when you do that test. If you then turn > your repeater TX on and nothing changes, you don't have desense. > > Chuck > WB2EDV > > > > - Original Message - > From: "Mathew Quaife" <[EMAIL PROTECTED]> > To: > Sent: Monday, July 26, 2004 10:48 PM > Subject: Re: [Repeater-Builder] Receiver Sensitivity Testing Through > Duplexer > > > > That I can do, I have another antenna that is up that I can hook to the > SM. > > From what I can tell I am not getting any desence, as I did have one > > operator about 25 miles away, listening through the receiver ouput, I > could > > here him just fine and that was with the repeat mode turned off. He would > > talk, and I would key up the transmitter, nothing would change. I'm > leading > > it back to the PL area, as was mentioned, I think it is killing the PL as > > they talk. I just want to make sure the duplexer is tuned up properly and > > all is working there. If its the PL, and is coming from the handie > talkie, > > not much I can do there. > > > > > > > Mathew, > > > > > > > > > > > > > > Yahoo! Groups Links > > > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer
You want the user to be a bit noisy when you do that test. If you then turn your repeater TX on and nothing changes, you don't have desense. Chuck WB2EDV - Original Message - From: "Mathew Quaife" <[EMAIL PROTECTED]> To: Sent: Monday, July 26, 2004 10:48 PM Subject: Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer > That I can do, I have another antenna that is up that I can hook to the SM. > From what I can tell I am not getting any desence, as I did have one > operator about 25 miles away, listening through the receiver ouput, I could > here him just fine and that was with the repeat mode turned off. He would > talk, and I would key up the transmitter, nothing would change. I'm leading > it back to the PL area, as was mentioned, I think it is killing the PL as > they talk. I just want to make sure the duplexer is tuned up properly and > all is working there. If its the PL, and is coming from the handie talkie, > not much I can do there. > > > > Mathew, > > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer
That I can do, I have another antenna that is up that I can hook to the SM. >From what I can tell I am not getting any desence, as I did have one operator about 25 miles away, listening through the receiver ouput, I could here him just fine and that was with the repeat mode turned off. He would talk, and I would key up the transmitter, nothing would change. I'm leading it back to the PL area, as was mentioned, I think it is killing the PL as they talk. I just want to make sure the duplexer is tuned up properly and all is working there. If its the PL, and is coming from the handie talkie, not much I can do there. > Mathew, > > No, you should not disturb any of the hookups between your duplexer and > antenna, transmitter, or receiver. What I meant by a "separate antenna" > is one connected to the output of your service monitor, and which > radiates a signal that is picked up by your repeater antenna. > > This method will prove or disprove whether desense is caused by your own > transmitter. It will also enable you to determine if desense is being > caused by a nearby transmitter on a different frequency, if the SINAD > reading suddenly drops while your repeater transmitter is disabled. If > this happens, you can use a spectrum analyzer to sweep the band several > MHz each side of your receiver frequency and note what carriers are > present at the same time your SINAD drops. As I noted in a previous > posting, a bandpass filter may be needed to eliminate desense caused by > a nearby transmitter. > > 73, Eric Lemmon WB6FLY > > Mathew Quaife wrote: > > > > Could I get by using a separate antenna to test for desense? Say leaving > > the antenna for the receiver through the duplexer and hooking the > > transmitter up to another antenna, would that work the same to test for > > desense. I tried to make an iso-tee, did not have real good luck with it, > > but then as far as a machinist, I have no luck at that, hihi > > > > > > Yahoo! Groups Links > > > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer
Actually the repeater is here at my home qth, only other transmitter is a 460 commercial repeater about 2 miles away, do don't think I am getting any problems from that one. Mathew - Original Message - From: "Mike WA6ILQ" <[EMAIL PROTECTED]> To: Sent: Monday, July 26, 2004 7:33 PM Subject: Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer > Forgot to mention one thing - you don't even need to visit the site > if the repeater has an autopatch (or even a remote base that is on > a different band) you can listen to the RX via the patch or remote > and let the main channel TX time out. If the quieting level in the > RX goes up exactly when the TX drops off that indicates a problem. > > Mike WA6ILQ > > At 07:14 PM 7/26/04, you wrote: > > >I like the idea but I'd use a parked mobile instead. HT's are hand held > >and can > >be moved which will change the signal level, plus they pull 3/4 to 1amp from > >the batteries and can suck them down, which also changes the signal level. > >The use of a parked mobile - set to the lowest power level it can do - > >eliminates > >both factors from the equation. > > > >Mike WA6ILQ > > > >At 06:57 PM 7/26/04, you wrote: > > > > >Here's one simple test. Have someone with an HT get into a noisy location, > > >then disable your repeater transmitter while listening on the local speaker. > > >If all of a sudden the HT becomes full quieting, you've got a desense > > >problem. > > > > > >Chuck > > >WB2EDV > > > > > > > > > > > >- Original Message - > > >From: "w9mwq" <[EMAIL PROTECTED]> > > >To: > > >Sent: Monday, July 26, 2004 8:01 PM > > >Subject: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer > > > > > > > > > > I need a little advise here. I want to test my repeater's > > > > sensitivity through the duplexer's while the transmitter is keyed > > > > up, into my Cushman Service Monitor. What is the best method of > > > > doing this? Do I need an isolator of some sort, or will the service > > > > monitor handle both the incoming power and the outgoing signal > > > > generator? It's a Cushman 6030 by the way. The repeater is working > > > > excellent for the most part. The problem that I am having is on > > > > weak signals, the audio is being chopped out, almost like the PL > > > > deck is shutting down. On the bench, the receiver is at about .25 > > > > microvolts sensitivity at 12 DB Sinad. Audio out of the transmitter > > > > is about 4KHz wide, and clean at 100 watts. Any suggestions. > > > > Handhelds are able to get in from about 4 miles away, mobiles have > > > > no troubles at 30 miles away. The antenna is only up at 60' right > > > > now, fed with 120' of 7/8" Andrews hardline. But it seems the > > > > handhelds are the one's having the problems, and their signal is not > > > > really that bad. Help please. > > > > > > > > Mathew > > > > > > > > > > > > > > > > > > > > > > > > > > > >Yahoo! Groups Links > > > > > > > > > > > > > > > > > > > > > > > > > >Yahoo! Groups Links > > > > > > > > > > > > > > > Yahoo! Groups Links > > > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer
Mathew, No, you should not disturb any of the hookups between your duplexer and antenna, transmitter, or receiver. What I meant by a "separate antenna" is one connected to the output of your service monitor, and which radiates a signal that is picked up by your repeater antenna. This method will prove or disprove whether desense is caused by your own transmitter. It will also enable you to determine if desense is being caused by a nearby transmitter on a different frequency, if the SINAD reading suddenly drops while your repeater transmitter is disabled. If this happens, you can use a spectrum analyzer to sweep the band several MHz each side of your receiver frequency and note what carriers are present at the same time your SINAD drops. As I noted in a previous posting, a bandpass filter may be needed to eliminate desense caused by a nearby transmitter. 73, Eric Lemmon WB6FLY Mathew Quaife wrote: > > Could I get by using a separate antenna to test for desense? Say leaving > the antenna for the receiver through the duplexer and hooking the > transmitter up to another antenna, would that work the same to test for > desense. I tried to make an iso-tee, did not have real good luck with it, > but then as far as a machinist, I have no luck at that, hihi Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer
Forgot to mention one thing - you don't even need to visit the site if the repeater has an autopatch (or even a remote base that is on a different band) you can listen to the RX via the patch or remote and let the main channel TX time out. If the quieting level in the RX goes up exactly when the TX drops off that indicates a problem. Mike WA6ILQ At 07:14 PM 7/26/04, you wrote: >I like the idea but I'd use a parked mobile instead. HT's are hand held >and can >be moved which will change the signal level, plus they pull 3/4 to 1amp from >the batteries and can suck them down, which also changes the signal level. >The use of a parked mobile - set to the lowest power level it can do - >eliminates >both factors from the equation. > >Mike WA6ILQ > >At 06:57 PM 7/26/04, you wrote: > > >Here's one simple test. Have someone with an HT get into a noisy location, > >then disable your repeater transmitter while listening on the local speaker. > >If all of a sudden the HT becomes full quieting, you've got a desense > >problem. > > > >Chuck > >WB2EDV > > > > > > > >- Original Message ----- > >From: "w9mwq" <[EMAIL PROTECTED]> > >To: > >Sent: Monday, July 26, 2004 8:01 PM > >Subject: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer > > > > > > > I need a little advise here. I want to test my repeater's > > > sensitivity through the duplexer's while the transmitter is keyed > > > up, into my Cushman Service Monitor. What is the best method of > > > doing this? Do I need an isolator of some sort, or will the service > > > monitor handle both the incoming power and the outgoing signal > > > generator? It's a Cushman 6030 by the way. The repeater is working > > > excellent for the most part. The problem that I am having is on > > > weak signals, the audio is being chopped out, almost like the PL > > > deck is shutting down. On the bench, the receiver is at about .25 > > > microvolts sensitivity at 12 DB Sinad. Audio out of the transmitter > > > is about 4KHz wide, and clean at 100 watts. Any suggestions. > > > Handhelds are able to get in from about 4 miles away, mobiles have > > > no troubles at 30 miles away. The antenna is only up at 60' right > > > now, fed with 120' of 7/8" Andrews hardline. But it seems the > > > handhelds are the one's having the problems, and their signal is not > > > really that bad. Help please. > > > > > > Mathew > > > > > > > > > > > > > > > > > > >Yahoo! Groups Links > > > > > > > > > > > > > > >Yahoo! Groups Links > > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer
Ok, looks like I need to get the Iso-tee made then. Mathew - Original Message - From: "Chuck Kelsey" <[EMAIL PROTECTED]> To: Sent: Monday, July 26, 2004 7:25 PM Subject: Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer > No. > > > > - Original Message - > From: "Mathew Quaife" <[EMAIL PROTECTED]> > To: > Sent: Monday, July 26, 2004 10:17 PM > Subject: Re: [Repeater-Builder] Receiver Sensitivity Testing Through > Duplexer > > > > Could I get by using a seperate antenna to test for desense? Say leaving > > the antenna for the receiver through the duplexer and hooking the > > transmitter up to another antenna, would that work the same to test for > > desense. I tried to make an iso-tee, did not heave real good luck with > it, > > but then as far as a machinest, I have to luck at that, hihi > > > > Mathew > > > > - Original Message - > > From: "Eric Lemmon" <[EMAIL PROTECTED]> > > To: > > Sent: Monday, July 26, 2004 6:09 PM > > Subject: Re: [Repeater-Builder] Receiver Sensitivity Testing Through > > Duplexer > > > > > > > Mathew, > > > > > > There may be more than one problem to consider. It is wise to check for > > > desense, but also be aware that some amateur-grade handhelds are > > > notorious for excessive PL deviation. Alincos are the worst, in my > > > opinion. My DJ-S11T had 1400 Hz of PL deviation out of the box, when > > > 400-700 Hz is ideal. When a commercial-grade repeater (MICOR, GE, etc.) > > > receives an input from a user with excessive PL deviation, the user's > > > voice may over-deviate the carrier, causing the PL to be clipped. When > > > this happens on a PL-required repeater, the repeater shuts down on voice > > > peaks. Of course, this symptom is made much worse when the voice > > > deviation is too high, as well. One way to check this is to use a > > > commercial-grade handheld radio to check for the same symptoms. > > > > > > To check for desense, you can use an "iso-tee" to inject a low-level > > > signal into the antenna feedline at the receiver frequency, while > > > monitoring the receiver audio at 12 dB SINAD with the repeater > > > disabled. Then enable the repeater so that the transmitter turns on. > > > The SINAD reading should drop no more than 1 dB. Some service monitors > > > will change modes when RF is detected, so you may want to use a separate > > > antenna, instead of the iso-tee, to get the test signal into the > > > receiver. > > > > > > If your repeater is at a site with other transmitters, you may need to > > > add some bandpass-only (NOT pass/notch) cavities between the duplexer > > > and the receiver input. As has been noted many times on this list, a > > > pass/notch or "BpBr" duplexer has almost no bandpass selectivity, and a > > > nearby transmitter many MHz away can easily cause desense in your > > > receiver if not filtered out with a dedicated bandpass cavity. > > > > > > 73, Eric Lemmon WB6FLY > > > > > > w9mwq wrote: > > > > > > > > I need a little advice here. I want to test my repeater's sensitivity > > through the duplexer, while the transmitter is keyed up, into my Cushman > > Service Monitor. What is the best method of doing this? Do I need an > > isolator of some sort, or will the service monitor handle both the > incoming > > power and the outgoing signal > > > > generator? It's a Cushman 6030 by the way. The repeater is working > > excellent for the most part. The problem that I am having is on weak > > signals, the audio is being chopped out, almost like the PL deck is > shutting > > down. On the bench, the receiver is at about .25 microvolts sensitivity > at > > 12 dB Sinad. Audio out of the transmitter > > > > is about 4 kHz wide, and clean at 100 watts. Any suggestions? > > Handhelds are able to get in from about 4 miles away, mobiles have no > > troubles at 30 miles away. The antenna is only up at 60' right now, fed > > with 120' of 7/8" Andrews hardline. But it seems the handhelds are the > ones > > having the problems, and their signal is not really that bad. Help > please. > > > > > > > > > > > > > > > > > > Yahoo! Groups Links > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Yahoo! Groups Links > > > > > > > > > > > > > > > > > > Yahoo! Groups Links > > > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer
No. - Original Message - From: "Mathew Quaife" <[EMAIL PROTECTED]> To: Sent: Monday, July 26, 2004 10:17 PM Subject: Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer > Could I get by using a seperate antenna to test for desense? Say leaving > the antenna for the receiver through the duplexer and hooking the > transmitter up to another antenna, would that work the same to test for > desense. I tried to make an iso-tee, did not heave real good luck with it, > but then as far as a machinest, I have to luck at that, hihi > > Mathew > > - Original Message - > From: "Eric Lemmon" <[EMAIL PROTECTED]> > To: > Sent: Monday, July 26, 2004 6:09 PM > Subject: Re: [Repeater-Builder] Receiver Sensitivity Testing Through > Duplexer > > > > Mathew, > > > > There may be more than one problem to consider. It is wise to check for > > desense, but also be aware that some amateur-grade handhelds are > > notorious for excessive PL deviation. Alincos are the worst, in my > > opinion. My DJ-S11T had 1400 Hz of PL deviation out of the box, when > > 400-700 Hz is ideal. When a commercial-grade repeater (MICOR, GE, etc.) > > receives an input from a user with excessive PL deviation, the user's > > voice may over-deviate the carrier, causing the PL to be clipped. When > > this happens on a PL-required repeater, the repeater shuts down on voice > > peaks. Of course, this symptom is made much worse when the voice > > deviation is too high, as well. One way to check this is to use a > > commercial-grade handheld radio to check for the same symptoms. > > > > To check for desense, you can use an "iso-tee" to inject a low-level > > signal into the antenna feedline at the receiver frequency, while > > monitoring the receiver audio at 12 dB SINAD with the repeater > > disabled. Then enable the repeater so that the transmitter turns on. > > The SINAD reading should drop no more than 1 dB. Some service monitors > > will change modes when RF is detected, so you may want to use a separate > > antenna, instead of the iso-tee, to get the test signal into the > > receiver. > > > > If your repeater is at a site with other transmitters, you may need to > > add some bandpass-only (NOT pass/notch) cavities between the duplexer > > and the receiver input. As has been noted many times on this list, a > > pass/notch or "BpBr" duplexer has almost no bandpass selectivity, and a > > nearby transmitter many MHz away can easily cause desense in your > > receiver if not filtered out with a dedicated bandpass cavity. > > > > 73, Eric Lemmon WB6FLY > > > > w9mwq wrote: > > > > > > I need a little advice here. I want to test my repeater's sensitivity > through the duplexer, while the transmitter is keyed up, into my Cushman > Service Monitor. What is the best method of doing this? Do I need an > isolator of some sort, or will the service monitor handle both the incoming > power and the outgoing signal > > > generator? It's a Cushman 6030 by the way. The repeater is working > excellent for the most part. The problem that I am having is on weak > signals, the audio is being chopped out, almost like the PL deck is shutting > down. On the bench, the receiver is at about .25 microvolts sensitivity at > 12 dB Sinad. Audio out of the transmitter > > > is about 4 kHz wide, and clean at 100 watts. Any suggestions? > Handhelds are able to get in from about 4 miles away, mobiles have no > troubles at 30 miles away. The antenna is only up at 60' right now, fed > with 120' of 7/8" Andrews hardline. But it seems the handhelds are the ones > having the problems, and their signal is not really that bad. Help please. > > > > > > > > > > > > Yahoo! Groups Links > > > > > > > > > > > > > > > > > Yahoo! Groups Links > > > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer
Very true indeed. I'm thinking it may be a combination of two things. First the handhelds are clipping the PL, I have a commercial Vertex HT, and it does not do it with that, but then I have mine turned down to about 400 Hertz. I'm sure the duplexers were tuned properly, as they were done by a service shop before being shipped, they are TXRX. Mathew > I like the idea but I'd use a parked mobile instead. HT's are hand held > and can > be moved which will change the signal level, plus they pull 3/4 to 1amp from > the batteries and can suck them down, which also changes the signal level. > The use of a parked mobile - set to the lowest power level it can do - > eliminates > both factors from the equation. > > Mike WA6ILQ > > At 06:57 PM 7/26/04, you wrote: > > >Here's one simple test. Have someone with an HT get into a noisy location, > >then disable your repeater transmitter while listening on the local speaker. > >If all of a sudden the HT becomes full quieting, you've got a desense > >problem. > > > >Chuck > >WB2EDV > > > > > > > >----- Original Message - > >From: "w9mwq" <[EMAIL PROTECTED]> > >To: > >Sent: Monday, July 26, 2004 8:01 PM > >Subject: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer > > > > > > > I need a little advise here. I want to test my repeater's > > > sensitivity through the duplexer's while the transmitter is keyed > > > up, into my Cushman Service Monitor. What is the best method of > > > doing this? Do I need an isolator of some sort, or will the service > > > monitor handle both the incoming power and the outgoing signal > > > generator? It's a Cushman 6030 by the way. The repeater is working > > > excellent for the most part. The problem that I am having is on > > > weak signals, the audio is being chopped out, almost like the PL > > > deck is shutting down. On the bench, the receiver is at about .25 > > > microvolts sensitivity at 12 DB Sinad. Audio out of the transmitter > > > is about 4KHz wide, and clean at 100 watts. Any suggestions. > > > Handhelds are able to get in from about 4 miles away, mobiles have > > > no troubles at 30 miles away. The antenna is only up at 60' right > > > now, fed with 120' of 7/8" Andrews hardline. But it seems the > > > handhelds are the one's having the problems, and their signal is not > > > really that bad. Help please. > > > > > > Mathew > > > > > > > > > > > > > > > > > > >Yahoo! Groups Links > > > > > > > > > > > > > > > Yahoo! Groups Links > > > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer
Could I get by using a seperate antenna to test for desense? Say leaving the antenna for the receiver through the duplexer and hooking the transmitter up to another antenna, would that work the same to test for desense. I tried to make an iso-tee, did not heave real good luck with it, but then as far as a machinest, I have to luck at that, hihi Mathew - Original Message - From: "Eric Lemmon" <[EMAIL PROTECTED]> To: Sent: Monday, July 26, 2004 6:09 PM Subject: Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer > Mathew, > > There may be more than one problem to consider. It is wise to check for > desense, but also be aware that some amateur-grade handhelds are > notorious for excessive PL deviation. Alincos are the worst, in my > opinion. My DJ-S11T had 1400 Hz of PL deviation out of the box, when > 400-700 Hz is ideal. When a commercial-grade repeater (MICOR, GE, etc.) > receives an input from a user with excessive PL deviation, the user's > voice may over-deviate the carrier, causing the PL to be clipped. When > this happens on a PL-required repeater, the repeater shuts down on voice > peaks. Of course, this symptom is made much worse when the voice > deviation is too high, as well. One way to check this is to use a > commercial-grade handheld radio to check for the same symptoms. > > To check for desense, you can use an "iso-tee" to inject a low-level > signal into the antenna feedline at the receiver frequency, while > monitoring the receiver audio at 12 dB SINAD with the repeater > disabled. Then enable the repeater so that the transmitter turns on. > The SINAD reading should drop no more than 1 dB. Some service monitors > will change modes when RF is detected, so you may want to use a separate > antenna, instead of the iso-tee, to get the test signal into the > receiver. > > If your repeater is at a site with other transmitters, you may need to > add some bandpass-only (NOT pass/notch) cavities between the duplexer > and the receiver input. As has been noted many times on this list, a > pass/notch or "BpBr" duplexer has almost no bandpass selectivity, and a > nearby transmitter many MHz away can easily cause desense in your > receiver if not filtered out with a dedicated bandpass cavity. > > 73, Eric Lemmon WB6FLY > > w9mwq wrote: > > > > I need a little advice here. I want to test my repeater's sensitivity through the duplexer, while the transmitter is keyed up, into my Cushman Service Monitor. What is the best method of doing this? Do I need an isolator of some sort, or will the service monitor handle both the incoming power and the outgoing signal > > generator? It's a Cushman 6030 by the way. The repeater is working excellent for the most part. The problem that I am having is on weak signals, the audio is being chopped out, almost like the PL deck is shutting down. On the bench, the receiver is at about .25 microvolts sensitivity at 12 dB Sinad. Audio out of the transmitter > > is about 4 kHz wide, and clean at 100 watts. Any suggestions? Handhelds are able to get in from about 4 miles away, mobiles have no troubles at 30 miles away. The antenna is only up at 60' right now, fed with 120' of 7/8" Andrews hardline. But it seems the handhelds are the ones having the problems, and their signal is not really that bad. Help please. > > > > > > Yahoo! Groups Links > > > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer
I like the idea but I'd use a parked mobile instead. HT's are hand held and can be moved which will change the signal level, plus they pull 3/4 to 1amp from the batteries and can suck them down, which also changes the signal level. The use of a parked mobile - set to the lowest power level it can do - eliminates both factors from the equation. Mike WA6ILQ At 06:57 PM 7/26/04, you wrote: >Here's one simple test. Have someone with an HT get into a noisy location, >then disable your repeater transmitter while listening on the local speaker. >If all of a sudden the HT becomes full quieting, you've got a desense >problem. > >Chuck >WB2EDV > > > >- Original Message - >From: "w9mwq" <[EMAIL PROTECTED]> >To: >Sent: Monday, July 26, 2004 8:01 PM >Subject: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer > > > > I need a little advise here. I want to test my repeater's > > sensitivity through the duplexer's while the transmitter is keyed > > up, into my Cushman Service Monitor. What is the best method of > > doing this? Do I need an isolator of some sort, or will the service > > monitor handle both the incoming power and the outgoing signal > > generator? It's a Cushman 6030 by the way. The repeater is working > > excellent for the most part. The problem that I am having is on > > weak signals, the audio is being chopped out, almost like the PL > > deck is shutting down. On the bench, the receiver is at about .25 > > microvolts sensitivity at 12 DB Sinad. Audio out of the transmitter > > is about 4KHz wide, and clean at 100 watts. Any suggestions. > > Handhelds are able to get in from about 4 miles away, mobiles have > > no troubles at 30 miles away. The antenna is only up at 60' right > > now, fed with 120' of 7/8" Andrews hardline. But it seems the > > handhelds are the one's having the problems, and their signal is not > > really that bad. Help please. > > > > Mathew > > > > > > > > > >Yahoo! Groups Links > > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer
Here's one simple test. Have someone with an HT get into a noisy location, then disable your repeater transmitter while listening on the local speaker. If all of a sudden the HT becomes full quieting, you've got a desense problem. Chuck WB2EDV - Original Message - From: "w9mwq" <[EMAIL PROTECTED]> To: Sent: Monday, July 26, 2004 8:01 PM Subject: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer > I need a little advise here. I want to test my repeater's > sensitivity through the duplexer's while the transmitter is keyed > up, into my Cushman Service Monitor. What is the best method of > doing this? Do I need an isolator of some sort, or will the service > monitor handle both the incoming power and the outgoing signal > generator? It's a Cushman 6030 by the way. The repeater is working > excellent for the most part. The problem that I am having is on > weak signals, the audio is being chopped out, almost like the PL > deck is shutting down. On the bench, the receiver is at about .25 > microvolts sensitivity at 12 DB Sinad. Audio out of the transmitter > is about 4KHz wide, and clean at 100 watts. Any suggestions. > Handhelds are able to get in from about 4 miles away, mobiles have > no troubles at 30 miles away. The antenna is only up at 60' right > now, fed with 120' of 7/8" Andrews hardline. But it seems the > handhelds are the one's having the problems, and their signal is not > really that bad. Help please. > > Mathew > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer
Mathew, There may be more than one problem to consider. It is wise to check for desense, but also be aware that some amateur-grade handhelds are notorious for excessive PL deviation. Alincos are the worst, in my opinion. My DJ-S11T had 1400 Hz of PL deviation out of the box, when 400-700 Hz is ideal. When a commercial-grade repeater (MICOR, GE, etc.) receives an input from a user with excessive PL deviation, the user's voice may over-deviate the carrier, causing the PL to be clipped. When this happens on a PL-required repeater, the repeater shuts down on voice peaks. Of course, this symptom is made much worse when the voice deviation is too high, as well. One way to check this is to use a commercial-grade handheld radio to check for the same symptoms. To check for desense, you can use an "iso-tee" to inject a low-level signal into the antenna feedline at the receiver frequency, while monitoring the receiver audio at 12 dB SINAD with the repeater disabled. Then enable the repeater so that the transmitter turns on. The SINAD reading should drop no more than 1 dB. Some service monitors will change modes when RF is detected, so you may want to use a separate antenna, instead of the iso-tee, to get the test signal into the receiver. If your repeater is at a site with other transmitters, you may need to add some bandpass-only (NOT pass/notch) cavities between the duplexer and the receiver input. As has been noted many times on this list, a pass/notch or "BpBr" duplexer has almost no bandpass selectivity, and a nearby transmitter many MHz away can easily cause desense in your receiver if not filtered out with a dedicated bandpass cavity. 73, Eric Lemmon WB6FLY w9mwq wrote: > > I need a little advice here. I want to test my repeater's sensitivity > through the duplexer, while the transmitter is keyed up, into my Cushman > Service Monitor. What is the best method of doing this? Do I need an > isolator of some sort, or will the service monitor handle both the incoming > power and the outgoing signal > generator? It's a Cushman 6030 by the way. The repeater is working > excellent for the most part. The problem that I am having is on weak > signals, the audio is being chopped out, almost like the PL deck is shutting > down. On the bench, the receiver is at about .25 microvolts sensitivity at > 12 dB Sinad. Audio out of the transmitter > is about 4 kHz wide, and clean at 100 watts. Any suggestions? Handhelds are > able to get in from about 4 miles away, mobiles have no troubles at 30 miles > away. The antenna is only up at 60' right now, fed with 120' of 7/8" Andrews > hardline. But it seems the handhelds are the ones having the problems, and > their signal is not really that bad. Help please. Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[Repeater-Builder] Receiver Sensitivity Testing Through Duplexer
I need a little advise here. I want to test my repeater's sensitivity through the duplexer's while the transmitter is keyed up, into my Cushman Service Monitor. What is the best method of doing this? Do I need an isolator of some sort, or will the service monitor handle both the incoming power and the outgoing signal generator? It's a Cushman 6030 by the way. The repeater is working excellent for the most part. The problem that I am having is on weak signals, the audio is being chopped out, almost like the PL deck is shutting down. On the bench, the receiver is at about .25 microvolts sensitivity at 12 DB Sinad. Audio out of the transmitter is about 4KHz wide, and clean at 100 watts. Any suggestions. Handhelds are able to get in from about 4 miles away, mobiles have no troubles at 30 miles away. The antenna is only up at 60' right now, fed with 120' of 7/8" Andrews hardline. But it seems the handhelds are the one's having the problems, and their signal is not really that bad. Help please. Mathew Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
RE: [Repeater-Builder] Receiver Sensitivity
It is receiver "A" Thank you Joe I find television very educating. Every time somebody turns on the set, I go into the other room and read a book. -- Groucho Marx, 1890-1977 -Original Message- From: dy3lmk143_13mhz [mailto:[EMAIL PROTECTED] Sent: Monday, April 19, 2004 8:05 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Receiver Sensitivity If I have two receivers A and B. Receiver A has a sensitivity of 0.25uV for a 12dB SINAD and Receiver B has a 0.35uV, which has a better sensitivity? is it Receiver A? Yahoo! Groups Links Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Receiver Sensitivity
If the value for Receiver B is also based upon a 12dB SINAD, yes, Receiver A is more sensitive. Expressed another way, Receiver B requires 40% more signal than Receiver A to achieve the same degree of quieting. Even so, a value of 0.35uV for 12dB SINAD is satisfactory for most applications. 73, Eric Lemmon WB6FLY dy3lmk143_13mhz wrote: > > If I have two receivers A and B. Receiver A has a sensitivity of > 0.25uV for a 12dB SINAD and Receiver B has a 0.35uV, which has a > better sensitivity? is it Receiver A? > > > Yahoo! Groups Links > > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Receiver Sensitivity
On Mon, 19 Apr 2004 12:05:19 -, dy3lmk143_13mhz wrote: >is it Receiver A? If they were both measured at 12dB Sinad, yes. The lower the number means that it takes less signal to achieve the required spec (12dB Sinad) Tedd Doda, VE3TJD Lazer Audio and Electronics Baden, Ontario, Canada Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[Repeater-Builder] Receiver Sensitivity
If I have two receivers A and B. Receiver A has a sensitivity of 0.25uV for a 12dB SINAD and Receiver B has a 0.35uV, which has a better sensitivity? is it Receiver A? Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
