Wjhat nobody seems to be pointing out is the simple fact that the Mastr II series does not normally use a 455 KHz IF frequency. It would have to be a special IFAS board with a second converter to get from the normal 11.2 MHz, or 9.4 MHz in low band and 800 MHz units, plus a very few that have a 10.7 MHz IF frequency. I have one of the latter boards, quite a bit different that the normal IFAS boards. So tell me just how you arrived at 455 KHz? A single conversion receiver using 455 KHz would be super prone to severe image problems. Please cite the exact location showing any Mastr II using a 455 KHz IF frequency? BTW, what schematics have you looked at for the Mastr II RX units?
Wayne WA2YNE Mastr II repeater on 441.950TX On Sat, 31 May 2008 15:55:28 -0500, Willis M. Hagler <[EMAIL PROTECTED]> wrote: > Hello Ron, > > The audio emphasis for FM is a different issue. When I put the > discriminator output from the Mastr II receiver on a analyzer you can > clearly see a spike way out at 455khz which I believe is the IF > frequency in the receiver. > > This controller has a auto-squelch feature (it does not use a COS/RUS > line at all) and it listens for the presence of high-frequency noise > coming off of the receiver to control the squelch. When a nice, full > quieting FM signal shows up the high frequency noise goes away and the > controller will detect this and kick on the transmitter. > > This detection circuit is behaving poorly on the Mastr II because this > strong 455khz component is throwing it off and making it shut down the > squelch because it thinks there's a lot of high-frequency noise even > when the signal is actually full quieting. > > Running the audio through a 10 mH inductor tied to a 1000pf cap to > ground should cause it to roll off the very high audio frequency and > solve the problem.... but here's what I run into trouble, there's > thousands of parts out there that say "10 mH inductor" so I'm over my > electronics head now! > > Thanks, > > Mark Hagler > W7WMH Seattle > > > -- Using Opera's revolutionary e-mail client: http://www.opera.com/mail/ ------------------------------------ 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: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] <*> 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/
