Re: [Repeater-Builder] intermod/interference??
I stand corrected. Eric had it pinned and I missed the fact the interference would only be heard *when* the remote base was enabled. I thought Dennis meant the intermod only happened when the remote base was transmitting, however after reading his follow-up, Eric is 100% correct. A screen shot of the intermod program (attached) confirms the data. Kevin Custer Kevin Custer wrote: I disagree, because he says it happens only when things are linked. I would think it has something to do with the link transmitter intermoding the repeater receiver, or the repeater transmitter intermoding the link receiver. He doesn't elaborate enough on when it happens, like after the linked repeater drops, or just when, but I don't believe it's a problem with the repeaters. Dennis, Your statement of " When the link is up and someone uses the 146.700/R it creates terrible interference and you can actually understand what is being said on the 70/R. The 70/R will not be heard or cause a problem until the 97/R is accessed while linked to the 147.24/R." is too vague and seems incorrect. If the two repeaters are linked, you should be able to understand what is being said on either machine, so I'm wondering what you are actually experiencing? At any rate, a notch cavity on the remote base tuned to the repeater transmit frequency, placed in the remote base line will help or eliminate intermod of the remote base. A notch cavity tuned for the remote base transmitter frequency, placed in the repeater receiver line will help or eliminate intermod of the repeater receiver. I don't have the time to run the numbers, so maybe you could run them again Eric? Kevin Custer Eric Lemmon wrote: Dennis, You have classic third-order intermodulation interference. 146.970 times 2 = 293.940 MHz. Subtract the 146.700 signal and you have 293.940 - 146.700 = 147.240 MHz, the output of your linked repeater. Other mixing products are possible. I suspect that neither the 146.970 repeater nor the 146.700 repeater has a circulator on the output. Bandpass cavities on the output are another option. 73, Eric Lemmon WB6FLY ki5fw wrote: Hey Guys; Why does my 146.970/Rptr when linked to a 147.240/Rptr get interference from a 146.700/Rptr. The 146.700/R is about 5-7 miles from my 146.970/R. When the link is up and someone uses the 146.700/R it creates terrible interference and you can actually understand what is being said on the 70/R. The 70/R will not be heard or cause a problem until the 97/R is accessed while linked to the 147.24/R. There is no problems when the link is down. Will a notch filter on the remote base T/cvr to notch out 146.700 be the cure? The remote base is frequency agile and wonder if the notch filter is the way to go. Guess it depends on how wide and deep the notch is??? I tried the intermod Calculator and I think I see what the problem is, but not sure if I'm looking at it correctly. TNX in Advance, Dennis ki5fw 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 the Yahoo! Terms of Service. <>
Re: [Repeater-Builder] intermod/interference??
I disagree, because he says it happens only when things are linked. I would think it has something to do with the link transmitter intermoding the repeater receiver, or the repeater transmitter intermoding the link receiver. He doesn't elaborate enough on when it happens, like after the linked repeater drops, or just when, but I don't believe it's a problem with the repeaters. Dennis, Your statement of " When the link is up and someone uses the 146.700/R it creates terrible interference and you can actually understand what is being said on the 70/R. The 70/R will not be heard or cause a problem until the 97/R is accessed while linked to the 147.24/R." is too vague and seems incorrect. If the two repeaters are linked, you should be able to understand what is being said on either machine, so I'm wondering what you are actually experiencing? At any rate, a notch cavity on the remote base tuned to the repeater transmit frequency, placed in the remote base line will help or eliminate intermod of the remote base. A notch cavity tuned for the remote base transmitter frequency, placed in the repeater receiver line will help or eliminate intermod of the repeater receiver. I don't have the time to run the numbers, so maybe you could run them again Eric? Kevin Custer Eric Lemmon wrote: Dennis, You have classic third-order intermodulation interference. 146.970 times 2 = 293.940 MHz. Subtract the 146.700 signal and you have 293.940 - 146.700 = 147.240 MHz, the output of your linked repeater. Other mixing products are possible. I suspect that neither the 146.970 repeater nor the 146.700 repeater has a circulator on the output. Bandpass cavities on the output are another option. 73, Eric Lemmon WB6FLY ki5fw wrote: Hey Guys; Why does my 146.970/Rptr when linked to a 147.240/Rptr get interference from a 146.700/Rptr. The 146.700/R is about 5-7 miles from my 146.970/R. When the link is up and someone uses the 146.700/R it creates terrible interference and you can actually understand what is being said on the 70/R. The 70/R will not be heard or cause a problem until the 97/R is accessed while linked to the 147.24/R. There is no problems when the link is down. Will a notch filter on the remote base T/cvr to notch out 146.700 be the cure? The remote base is frequency agile and wonder if the notch filter is the way to go. Guess it depends on how wide and deep the notch is??? I tried the intermod Calculator and I think I see what the problem is, but not sure if I'm looking at it correctly. TNX in Advance, Dennis ki5fw 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 the Yahoo! Terms of Service.
Re: [Repeater-Builder] intermod/interference??
Dennis, You have classic third-order intermodulation interference. 146.970 times 2 = 293.940 MHz. Subtract the 146.700 signal and you have 293.940 - 146.700 = 147.240 MHz, the output of your linked repeater. Other mixing products are possible. I suspect that neither the 146.970 repeater nor the 146.700 repeater has a circulator on the output. Bandpass cavities on the output are another option. 73, Eric Lemmon WB6FLY ki5fw wrote: > Hey Guys; > Why does my 146.970/Rptr when linked to a 147.240/Rptr get interference > from a 146.700/Rptr. The 146.700/R is about 5-7 miles from my > 146.970/R. When the link is up and someone uses the 146.700/R it > creates terrible interference and you can actually understand what is > being said on the 70/R. > The 70/R will not be heard or cause a problem until the 97/R is > accessed while linked to the 147.24/R. There is no problems when the > link is down. > Will a notch filter on the remote base T/cvr to notch out 146.700 be > the cure? The remote base is frequency agile and wonder if the notch > filter is the way to go. Guess it depends on how wide and deep the > notch is??? > I tried the intermod Calculator and I think I see what the problem is, > but not sure if I'm looking at it correctly. > > TNX in Advance, > Dennis ki5fw > > > 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/
[Repeater-Builder] intermod/interference??
Hey Guys; Why does my 146.970/Rptr when linked to a 147.240/Rptr get interference from a 146.700/Rptr. The 146.700/R is about 5-7 miles from my 146.970/R. When the link is up and someone uses the 146.700/R it creates terrible interference and you can actually understand what is being said on the 70/R. The 70/R will not be heard or cause a problem until the 97/R is accessed while linked to the 147.24/R. There is no problems when the link is down. Will a notch filter on the remote base T/cvr to notch out 146.700 be the cure? The remote base is frequency agile and wonder if the notch filter is the way to go. Guess it depends on how wide and deep the notch is??? I tried the intermod Calculator and I think I see what the problem is, but not sure if I'm looking at it correctly. TNX in Advance, Dennis ki5fw 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/
