Kjeld: Do you have access to another 10 MHz reference that could be substituted and used to compare? It does not have to be high accuracy for the comparison test.
I suspect a 10 kHz switching power supply or some other 10 kHz source associated with your GPSDO as causing the problem. You might also try making sure the case of the FLEX-1500 shares a common ground with the GPSDO. Do not depend on the shield of the 10 MHz coax, since it floats at the FLEX-1500 input, to allow the 1500 to reject ground loop noise. --- Graham / KE9H == On Tue, Apr 12, 2011 at 10:23 AM, Kjeld Bülow Thomsen <[email protected]> wrote: > I’m using my Flex-1500 with transverters on 1,3 – 24 GHz. The radio and > most > of the transverters are locked to a 10 MHz GPS-disciplined oscillator. When > working weak signals there are only very few spurious frequencies. During > the last weeks there has been tropo conditions with signals in the 59 > +20-30 > dB range. All these signals appeared full of spurious +/- 20 kHz. As all > signals was looking in the same way when exceeding S9 I decided to > investigate the problem. > > > > The pictures on http://www.oz1ff.dk/pages/flexradio.html a screen dump of > a > -60 dBm signal on 28,2 MHz from a clean source. Dia1 is with external > reference and shows +/- 10 kHz spurious. Dia2 shows the signal with the 10 > MHz reference switched off. Increasing the signal generator level to more > than -40 dBm with 30 dB preamp gain overloads the receiver. But that is as > specified. The level from the external 10 MHz source is +2 dBm and sine > wave. > > > > The external reference is essential for weak signal work. I don’t expect > this to be a software problem. Any suggestions for a solution to this > annoying problem? > > > > Vy 73 de OZ1FF - Kjeld > > > > Phone +45 7352 6050 > > SMS +45 4021 1119 > > Skype oz1ff-1 > > > > <mailto:[email protected]> mailto:[email protected] > > <http://www.oz1ff.dk/> http://www.oz1ff.dk > > > > _______________________________________________ > FlexRadio Systems Mailing List > [email protected] > http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz > Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ > Knowledge Base: http://kc.flexradio.com/ Homepage: > http://www.flexradio.com/ > _______________________________________________ FlexRadio Systems Mailing List [email protected] http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/
