Display MoreHello Pedro,
the Pluto will most likely not work properly with a 10 MHz reference. A friend tested 4 or 5 Plutos and only one of them worked properly with reference frequencies of 20 Mhz and below. Therefore it is advised to use reference frequencies higher than 20 MHz, 40 MHz or even 50 MHz is strongly recommended.
If you generate your reference by using frequency doublers e.g. 40 MHz out of 10 MHz you will loose the same amount of phase noise performance as running the PLL with a lower reference frequency. Of course this is only true if the doubler is ideal and also the PLL.
In a latest design Kurt DJ0ABR has developed a simple unit using a 100MHz OCXO and 2 dividers :2. With this we generate 50 MHz for the Pluto and 25 MHz for the reference frequency of the LNB. Simple and very good. The circuit of Kurt allows also to lock the OCXO additionally to a GPSDO. I have buil this up and it works very fine. The GPSDO is not really needed as the OCXO is very stable.
Kind regards
Matthias
Hi Pedro.
Great project !
Link:
https://projects.dj0abr.de/doku.php?id=en:sat:plutolnb
73!
PY1SAN
Den verwendeten Regler hab ich in anderen Projekten schon erfolgreich verwendet, und deswegen nicht lange gesucht. Die 5V zweige ich schon sehr früh an D3 ab, direkt am USB Eingang. So bin ich bezgl. der Stabilität der 3v3 zumindest sicher (hängt ja auch die Abstimmspannung dran).