Right. That's what I posted. Granted, I said 2A-1B as opposed to 2A-B, but I used the standard convention. Either way, it's the same math. I only posted the 2A-1B and 2B-1A (which is the same as switching the frequencies around for A and B).
2A+1B, or 2B+1A won't come out to anything close to either of the two frequencies in question. That's why I didn't post those. Unless you have a problem with two VHF repeaters coming into a UHF repeater, for example, you can ignore any of the 2X+1Y third order mixes. However, the problem is not identified until you get into the 3A-2B, or 3B-2A calculations (fifth order mixing). Again, the 3A+2B, and 3B+2A won't come out anywhere close, so you can write those off. However, 3A-2B, or 3B-2A come out exactly 'right'. That's where the problem is. How can you fix it? It depends on the type of duplexer you are using. Changing that alone would solve it. Circulators could if it's mixing in the TXs. Of course, separating the two repeater could solve it. But, if it's mixing in a third party transmitter, you will be dealing with a product that is already on-frequency. There isn't anything you can do about that that won't destroy the repeater performance. You could put some filters to notch out one or both of your TXs on the third party equipment, but don't count of that being a viable option. Again, moving the two repeaters further apart or changing frequency may be the only solution. Joe M. Dave Frechette wrote: > > A=frequency 1 > B=frequency 2 > > Formula for your frequency products is 2A+b, 2A-B, 2B+A, 2B-A. Simple > math! > > -----Original Message----- > From: mch [mailto:[EMAIL PROTECTED] > 2A-1B: > 147.225 + 147.225 - 146.925 = 147.525 > 146.925 + 146.925 - 147.225 = 146.625 > > (these are both OK unless you mix the results with the outputs, > as each are 600 kHz off the TX of the other repeater) > > 3A-2B: > 147.225 + 147.225 + 147.225 - 146.925 - 146.925 = 147.825 (sound > familiar?) > 146.925 + 146.925 + 146.925 - 147.225 - 147.225 = 146.325 (again, sound > familiar?) > > Each of these cases results on the two TXs mixing and ending up with > products on the inputs of the other. 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/
