----- Original Message -----From: Jim SanfordCc: [email protected] ; Bdale Garbee ; Bill Ress ; Dave Black (Home) ; Dave Black (Work) ; Dave hartzell ; David Smith ; Dick Jannson ; Don Ferguson ; John B. Stephensen ; Juan.Rivera (Work) ; Lyle Johnson ; Phil Karn ; Robert Davis KF4KSS ; Robert McGwier ; [email protected] Com ; Stephen Moraco ; 'Steven Bible' ; 'William A Schmitt'Sent: Monday, June 11, 2007 00:44 UTCSubject: Re: 70 cm Receiver Spur Source FoundJuan:
Can you "sniff" the various lines from CAN-Do! to get an idea of which is the source?
Also, my memory is that we still have an open issue with the passband ripple -- or did that get resolved and I missed it?
Again, thanks for all you're doing.
Juan Rivera wrote:
The source of the spurs in the 70 cm prototype receiver is the CAN-Do module.
This is the receiver IF output as designed
(powered from pins 39 and 40 of the CAN-Do Module)
This is the receiver running off of a separate power source
(bypassing the CAN-Do Module +13 volt output on pins 39 and 40)
This is the same configuration as above, but with the CAN-Do module shut down
From the above it appears that:
<!--[if !supportLists]-->1. <!--[endif]-->The CAN-Do module is the source of all the spurs that I see
<!--[if !supportLists]-->2. <!--[endif]-->None of the spurs are being generated by the receiverís internal power supplies
<!--[if !supportLists]-->3. <!--[endif]-->Some, but not all, of the noise is entering the receiver via the switched +13 volt CAN-Do output on pins 39 and 40
<!--[if !supportLists]-->4. <!--[endif]-->The remainder of the noise could be entering the receiver on other CAN-Do pins, or being radiated to receiver components or traces in close proximity
See my log for all the intermediate steps I took to reach these conclusions.
Remaining RF issues:
<!--[if !supportLists]-->1. <!--[endif]-->Phase noise
<!--[if !supportLists]-->2. <!--[endif]-->Microphonics