The possible sources are the PLLs and the logic inside the onboard TCXO. Can you turn off the internal TCXO by removing the ferrite bead feeding it power and use and external 10 MHz reference?
If this doesn't work, the PLL division ratios can be changed.
----- Original Message -----
From: Juan Rivera
To: 'John B. Stephensen'
Cc: [email protected] ; 'Bill Ress' ; 'Dave Black (Home)' ; 'Dave Black (Work)' ; 'Dave hartzell' ; 'David Smith' ; 'Don Ferguson' ; 'Juan.Rivera (Work)' ; '[email protected] Com'
Sent: Monday, July 02, 2007 03:19 UTC
Subject: RE: 10.7 MHz Spur



The short answer is 'no'.  Click here for details and scroll to the bottom of the log...




-----Original Message-----
From: John B. Stephensen [mailto:[email protected]]
Sent: Sunday, July 01, 2007 2:42 PM
To: [email protected]
Cc: [email protected]; Bill Ress; Dave Black (Home); Dave Black (Work); Dave hartzell; David Smith; Don Ferguson; Juan. Rivera (Home); Juan.Rivera (Work); [email protected]. Com
Subject: Re: 10.7 MHz Spur


Does the spur go away if the external reference is on (whether or not it is

routed to the PLLs)?







----- Original Message -----

From: "Juan Rivera" <[email protected]>

To: "John B. Stephensen" <[email protected]>

Cc: <[email protected]>; "Bill Ress" <[email protected]>; "Dave Black

(Home)" <[email protected]>; "Dave Black (Work)"

<[email protected]>; "Dave hartzell" <[email protected]>; "David

Smith" <[email protected]>; "Don Ferguson" <[email protected]>; "Juan. Rivera

(Home)" <[email protected]>; "Juan.Rivera (Work)"

<[email protected]>; "[email protected] Com" <[email protected]>

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


> 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