Does the spur go away if the external reference is on (whether or not it is routed to the PLLs)?
73,
John KD6OZH
----- Original Message ----- From: "Juan Rivera" juan-rivera@sbcglobal.net To: "John B. Stephensen" kd6ozh@comcast.net Cc: eagle@amsat.org; "Bill Ress" bill@hsmicrowave.com; "Dave Black (Home)" dblack1054@yahoo.com; "Dave Black (Work)" dblack@mail.arc.nasa.gov; "Dave hartzell" hartzell@gmail.com; "David Smith" w6te@msn.com; "Don Ferguson" kd6ire@sbcglobal.net; "Juan. Rivera (Home)" juan-rivera@sbcglobal.net; "Juan.Rivera (Work)" Juan.Rivera@gd-ais.com; "Samsonoff@Mac. Com" samsonoff@mac.com Sent: Saturday, June 30, 2007 14:22 UTC Subject: 10.7 MHz Spur
John,
I found the source of the 10.7 MHz spur. It's being generated inside the receiver itself. This is the first spur I have found that is not caused by switching power supplies.
The origin appears to be in the 10 MHz reference area. I turned off and unplugged the SDR-IQ and fed the IF output from the 70 cm Receiver to my TS-2000. The spur is still there.
Next I connected the RF input to my sniffer loop and moved it around the PCB surface. I get the strongest signal near the long trace between the two Freq inputs to U4 and U9, the two phased-locked loops.
73,
Juan