John,

 

This is going to require some uninterrupted time when I can think.  It’s too difficult to get much done on work nights so I’ll probably have to put it off until the weekend, or perhaps the 4th…

 

73, Juan

 

From: John B. Stephensen [mailto:kd6ozh@comcast.net]
Sent: Sunday, July 01, 2007 9:01 PM
To: juan-rivera@sbcglobal.net
Cc: eagle@amsat.org; 'Bill Ress'; 'Dave Black (Home)'; 'Dave Black (Work)'; 'Dave hartzell'; 'David Smith'; 'Don Ferguson'; 'Juan.Rivera (Work)'; 'Samsonoff@Mac. Com'
Subject: Re: 10.7 MHz Spur

 

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.

 

73,

 

John

KD6OZH

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

From: Juan Rivera

To: 'John B. Stephensen'

Cc: eagle@amsat.org ; 'Bill Ress' ; 'Dave Black (Home)' ; 'Dave Black (Work)' ; 'Dave hartzell' ; 'David Smith' ; 'Don Ferguson' ; 'Juan.Rivera (Work)' ; 'Samsonoff@Mac. Com'

Sent: Monday, July 02, 2007 03:19 UTC

Subject: RE: 10.7 MHz Spur

 

John,

 

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

 

Juan

 

-----Original Message-----
From: John B. Stephensen [mailto:kd6ozh@comcast.net]
Sent: Sunday, July 01, 2007 2:42 PM
To: juan-rivera@sbcglobal.net
Cc: eagle@amsat.org; Bill Ress; Dave Black (Home); Dave Black (Work); Dave hartzell; David Smith; Don Ferguson; Juan. Rivera (Home); Juan.Rivera (Work); Samsonoff@Mac. 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)?

 

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

> 

>