Re: [Repeater-Builder] UHF Micor (mobile) spur (more test results)
It sounds like you are on the right track! Keep going!! A few years ago I had a local ham tell me my UHF repeater was producing a spur on his UHF output. He made a fuss that I was not running good gear, or adequite filtering. I assured him that I was fine had checked it out with my equipment. He offered to come to my repeater site with a spectrum analyzer mentioned several times that since he was an engineer (working for Fujitsu) he would like to trouble shoot the problem at my location would help repair. I declined his request. (Apparently he did not realize that I also am an engineer working in FM broadcast) He then requested I turn off my repeater, I refused. He then found out that my repeater transmitter was a GE Mastr Pro suggested I upgrade to a solid state transmitter, claiming that an old tube PA was likely the cause of the problem (I refused) He then made a fuss with the repeater coordination coucil, of which we were BOTH board members. Eventually, it came down to a local ham (WA7ABU) member of the coordination board inspecting BOTH our repeater sites. The inspector found a mix that was occuring in HIS (the complaining party's) location!! (Which was a solid state PA deck!!) Obviously, this has noting to do with the subject but is a fun story. -- Original Message -- Received: Fri, 01 Jul 2005 06:54:32 AM CDT From: Paul Kelley [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] UHF Micor (mobile) spur (more test results) I just spent another night poking around in this thing. Sniffing around the transmitter with a receiver and very small probe antenna I am reasonably certain the spur is present at Q305 (exciter mixer) and all subsequent stages. Using a general coverage receiver the fundamental output of the channel element (19.195833 MHz) seems free of spurs. I realize the third harmonic of the channel element is selected by the filter but I have no receiver covering that range. Similarly, the 16.7 MHz out of the offset oscillator seems OK. There are some very weak (more than -100 dB) spurs above 16.7 but it is absolutely quiet at 15.790 which is what would be required to cause my +910 kHz spur. So I suspect a problem in either the exciter mixer (Q305) or somewhere in the injection multipliers (Q101, 102, 103) on the receiver RF IF board). No amount of tuning or detuning these stages eliminates it. It still seems odd that I have two Micors with an identical spur problem. Any thoughts on what to try next? Paul N1BUG 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/
Re: [Repeater-Builder] UHF Micor (mobile) spur (more test results)
Obviously, this has noting to do with the subject but is a fun story. I've got one that I'm trying to track down.. A local 2M machine, on 146.730, is having a problem we call the horrible noise. I've never heard anything like it, and I've had no success at recording it. It sounds like some sort of a feedback loop, in that I think that I can hear 'reverb like effects in the sound. It happens in wet weather, and there have been a bunch of theories put forward, but nothing makes sense. At one point, it was blamed on a repeater I now own, but we disproved that by taking it off the air entirely, while the horrible noise continued. The latest theory is that it is related to the replacement of some capacitors in the final amp of the kenwood repeater, but I'm skeptical. 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/
Re: [Repeater-Builder] UHF Micor (mobile) spur (more test results)
I just spent another night poking around in this thing. Sniffing around the transmitter with a receiver and very small probe antenna I am reasonably certain the spur is present at Q305 (exciter mixer) and all subsequent stages. Using a general coverage receiver the fundamental output of the channel element (19.195833 MHz) seems free of spurs. I realize the third harmonic of the channel element is selected by the filter but I have no receiver covering that range. Similarly, the 16.7 MHz out of the offset oscillator seems OK. There are some very weak (more than -100 dB) spurs above 16.7 but it is absolutely quiet at 15.790 which is what would be required to cause my +910 kHz spur. So I suspect a problem in either the exciter mixer (Q305) or somewhere in the injection multipliers (Q101, 102, 103) on the receiver RF IF board). No amount of tuning or detuning these stages eliminates it. It still seems odd that I have two Micors with an identical spur problem. Any thoughts on what to try next? Paul N1BUG 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/
Re: [Repeater-Builder] UHF Micor (mobile) spur (more test results)
On Friday 01 July 2005 08:43 am, Dave VanHorn wrote: Any possibility that it's coming from the power supply, and not actually the amplifier at all? Do you get it when running from a battery? Good thought. I tried 3 different power supplies and finally a battery. There is definitely something funny going on in the Micors. Paul 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/
Re: [Repeater-Builder] UHF Micor (mobile) spur (more test results)
At 08:03 AM 7/1/2005, Paul Kelley wrote: On Friday 01 July 2005 08:43 am, Dave VanHorn wrote: Any possibility that it's coming from the power supply, and not actually the amplifier at all? Do you get it when running from a battery? Good thought. I tried 3 different power supplies and finally a battery. There is definitely something funny going on in the Micors. Ok, glad to rule that out. . I've seen badly designed or broken switchers with significant HF noise on the output, and even linear supplies can do this. 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/
