So very true. Neil - WA6KLA
Ronald Schiller wrote: > > Hi Guys, Any of you ever hear of Modulation Acceptance? Test the receiver > and find out. No receiver made has a linear Pass Band and sometimes by > running the if cans to the second resonant point, you can find a more linear > point. Another trick is to change the 2nd conversion xtal above or below the > if. Bottom line is test the Receiver. Clean up the mixers, Birdies out of > the oscillator will kill you. Ron wa6unm > > -----Original Message----- > From: Steve S. Bosshard (NU5D) [mailto:[EMAIL PROTECTED] > Sent: Tuesday, April 27, 2004 7:34 PM > To: Repeater-Builder@yahoogroups.com > Subject: RE: [Repeater-Builder] Help on Interference > > Oh Really? If you ASSUME (and you know how I mean that word) that each TX > HAS to have 20 kHz of bandwidth, I guess so, but that's not necessary. Only > if you have 5 kHz deviation and a 5 kHz of frequency response (or some > equivalent combination) will that be true. Most radios, including ham > radios, tend to have lower response, and many, especially if set up > correctly, will have less than 5 kHz of deviation. > In reality, each will have closer to 3 kHz response and 4.5 kHz of > deviation. That adds up to about 15 kHz of bandwidth, and ZERO overlapping. > IOW: > > 146R325 occupies from 146.3175 to 146.3325 146.310 occupies from 146.3025 > to 146.3175 > > They SHARE... NOTHING! > > Now, if your RECEIVER is passing 146.315 to 146.335, yes EXPECT problems, > as your OWN RECEIVER is causing the problem. I tend to think that's the > problem in this case. Of course, it could be users with TXs that are too > wide, too. > > Reply: > > Please refer to modulation index and Bessel functions. The frequency > response is 300 to 3000 hz emphasized at 3db per octave. Transmitter > instantaneous deviation is supposed to be limited to +/- 5 kc deviation > from center. Significant sidebands in FM extend beyond the deviation > limit, hence emission designator 20K0F3E that equates to about 16 khz > occupied plus a guard band on either side. > > They share part of the same channel (honest - I would not kid about > something like this). Has nothing to do with receiver - both transmitters > share common ground. > > Very truly yours, > > Steve Bosshard > AR SK > > Steve > > 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/
