Re: [Repeater-Builder] Intermod Calculation
I've had luck finding these kinds of problems by bringing a spectrum analyzer to the site and connecting it to an antenna. I look at 10-20Mhz sections of the spectrum and try to find a spike that comes up at the same time as the interference. It is time consuming and dependent upon the interference happening frequently, but it works quite well. It beats sitting around trying to analyze the problem to death and you feel like you're at least doing something. Sometimes you need to prove where the trouble is not happening help you focus on where it really is. 73, Joe, K1ike On 8/20/2010 6:35 PM, Tim Sawyer wrote: I have paging intermod from 157.740 Mhz.
Re: [Repeater-Builder] Intermod Calculation
That's how I found 157.74. We're going back up on Tuesday to look some more. -- Tim :wq On Aug 21, 2010, at 4:52 AM, Joe wrote: I've had luck finding these kinds of problems by bringing a spectrum analyzer to the site and connecting it to an antenna. I look at 10-20Mhz sections of the spectrum and try to find a spike that comes up at the same time as the interference.
RE: [Repeater-Builder] Intermod Calculation
Before we get into the math, an important question that needs to be answered is whether or not this mix occurs when your repeater transmitter is unkeyed. --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Tim Sawyer Sent: Friday, August 20, 2010 6:36 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Intermod Calculation I have paging intermod from 157.740 Mhz. My receiver is on 144.540 Mhz. I'm 100% sure there is another transmitter involved in the mix because sometimes the pager is transmitting and I have no interference. I have an intermod calculator program but it wants all the known transmitters and the target receiver. But I need to solve for an unknown transmitter. Is there a way to calculate the other possible soruce(s)? -- Tim :wq
Re: [Repeater-Builder] Intermod Calculation
Most likely suspects would be 151.140 and 170.940 MHz. Joe M. Tim Sawyer wrote: I have paging intermod from 157.740 Mhz. My receiver is on 144.540 Mhz. I'm 100% sure there is another transmitter involved in the mix because sometimes the pager is transmitting and I have no interference. I have an intermod calculator program but it wants all the known transmitters and the target receiver. But I need to solve for an unknown transmitter. Is there a way to calculate the other possible soruce(s)? -- Tim :wq Yahoo! Groups Links
Re: [Repeater-Builder] Intermod Calculation
I'll watch those. How did you calculate them? -- Tim :wq On Aug 20, 2010, at 5:38 PM, MCH wrote: Most likely suspects would be 151.140 and 170.940 MHz. Joe M. Tim Sawyer wrote: I have paging intermod from 157.740 Mhz. My receiver is on 144.540 Mhz. I'm 100% sure there is another transmitter involved in the mix because sometimes the pager is transmitting and I have no interference. I have an intermod calculator program but it wants all the known transmitters and the target receiver. But I need to solve for an unknown transmitter. Is there a way to calculate the other possible soruce(s)? -- Tim :wq Yahoo! Groups Links
Re: [Repeater-Builder] Intermod Calculation
2A-B solving for once for A and once for B. Or, to make it more clear (maybe), the sum of your receiver and half the difference between the two (IOW, the frequency directly half way between two two others), and the sum of the full difference plus the paging transmitter frequency. Putting it another way which might be easier to understand: The frequencies half way from your RX to the paging TX, and the frequency twice as far from the two (in the direction of the transmitter) Either way, it's all 2A-B: 2(151.140) - 157.740 = 144.540 2(157.740) - 170.940 = 144.540 Joe M. Tim Sawyer wrote: I'll watch those. How did you calculate them? -- Tim :wq On Aug 20, 2010, at 5:38 PM, MCH wrote: Most likely suspects would be 151.140 and 170.940 MHz. Joe M. Tim Sawyer wrote: I have paging intermod from 157.740 Mhz. My receiver is on 144.540 Mhz. I'm 100% sure there is another transmitter involved in the mix because sometimes the pager is transmitting and I have no interference. I have an intermod calculator program but it wants all the known transmitters and the target receiver. But I need to solve for an unknown transmitter. Is there a way to calculate the other possible soruce(s)? -- Tim :wq Yahoo! Groups Links Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/Repeater-Builder/join (Yahoo! ID required) * To change settings via email: repeater-builder-dig...@yahoogroups.com repeater-builder-fullfeatu...@yahoogroups.com * To unsubscribe from this group, send an email to: repeater-builder-unsubscr...@yahoogroups.com * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
