This really is Time Nuts related. Keep reading. I recently bought some surplus Motorola UHF mobiles. They came with the previous frequencies blanked and only channel one programmed with 460.000 MHz. I put all of them on the bench to do a quick test to see if they transmitted and received. Upon power on, every one was receiving a strong carrier on the programmed frequency of 460 MHz. Firing up the service monitor with a small whip antenna, I found a -70 dBm carrier, right on 460 MHz. Taking a handheld scanner around the house and outside, it seemed that the problem was in my house, but I couldn't localize it with the scanner. I started turning off circuit breakers until the carrier went away. Then I went around, unplugging things individually. You won't believe what the culprit was. I have had some 10 MHz, Micro Crystal OCXO's (DIP 14) aging for quite a while, intending to use them in a few projects eventually. Yep, it was the OCXO's. I am surprised that the OXCO's would be putting out a carrier at 460 MHz, and such a strong one. This has been going on for quite a while. If I hadn't had these Motorola radios that just happened to be programmed for 460 MHz, who knows if or when I would have noticed this. Joe Gray W5JG

HI Probably what is going on is that the OCXO’s have a parasitic oscillaton in the UHF region. It has injection locked to the 10 MHz. You get a signal that is much higher level than any harmonic relation would predict. I’d try fiddling the bypassing and load …. Bob > On Oct 28, 2016, at 8:43 PM, Joseph Gray <jgray@zianet.com> wrote: > > This really is Time Nuts related. Keep reading. > > I recently bought some surplus Motorola UHF mobiles. They came with > the previous frequencies blanked and only channel one programmed with > 460.000 MHz. > > I put all of them on the bench to do a quick test to see if they > transmitted and received. Upon power on, every one was receiving a > strong carrier on the programmed frequency of 460 MHz. Firing up the > service monitor with a small whip antenna, I found a -70 dBm carrier, > right on 460 MHz. > > Taking a handheld scanner around the house and outside, it seemed that > the problem was in my house, but I couldn't localize it with the > scanner. I started turning off circuit breakers until the carrier went > away. Then I went around, unplugging things individually. You won't > believe what the culprit was. > > I have had some 10 MHz, Micro Crystal OCXO's (DIP 14) aging for quite > a while, intending to use them in a few projects eventually. Yep, it > was the OCXO's. I am surprised that the OXCO's would be putting out a > carrier at 460 MHz, and such a strong one. > > This has been going on for quite a while. If I hadn't had these > Motorola radios that just happened to be programmed for 460 MHz, who > knows if or when I would have noticed this. > > Joe Gray > W5JG > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there.

Hi, On a related note, I remember when Pendulum was testing a rubidium and it had more jitter than motivated by the integrated phase-noise slopes, so they where curious about it. As I had just brought in my SIA3000 for them to have fun with, I hooked it up and already in the oscilloscope view I found small bumps spread out over the sine. Turned out to be the 100 MHz used for the rubidium lamp that polluted the output. You rarely do a plot out to 90 MHz offset of the 10 MHz carrier on phase-noise plots, you rather call it harmonics which wasn't listed. Cheers, Magnus On 10/29/2016 03:58 AM, Bob Camp wrote: > HI > > Probably what is going on is that the OCXO’s have a parasitic oscillaton in the UHF > region. It has injection locked to the 10 MHz. You get a signal that is much higher > level than any harmonic relation would predict. > > I’d try fiddling the bypassing and load …. > > Bob > >> On Oct 28, 2016, at 8:43 PM, Joseph Gray <jgray@zianet.com> wrote: >> >> This really is Time Nuts related. Keep reading. >> >> I recently bought some surplus Motorola UHF mobiles. They came with >> the previous frequencies blanked and only channel one programmed with >> 460.000 MHz. >> >> I put all of them on the bench to do a quick test to see if they >> transmitted and received. Upon power on, every one was receiving a >> strong carrier on the programmed frequency of 460 MHz. Firing up the >> service monitor with a small whip antenna, I found a -70 dBm carrier, >> right on 460 MHz. >> >> Taking a handheld scanner around the house and outside, it seemed that >> the problem was in my house, but I couldn't localize it with the >> scanner. I started turning off circuit breakers until the carrier went >> away. Then I went around, unplugging things individually. You won't >> believe what the culprit was. >> >> I have had some 10 MHz, Micro Crystal OCXO's (DIP 14) aging for quite >> a while, intending to use them in a few projects eventually. Yep, it >> was the OCXO's. I am surprised that the OXCO's would be putting out a >> carrier at 460 MHz, and such a strong one. >> >> This has been going on for quite a while. If I hadn't had these >> Motorola radios that just happened to be programmed for 460 MHz, who >> knows if or when I would have noticed this. >> >> Joe Gray >> W5JG >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. >