Re: Understanding Spurious Emissions


Howard Fidel
 

Got it. Thanks. I never saw on my uBitx the numbers you reported, but I don't think it is a serious problem for a barefoot uBitx, which is the main point I was trying to make. It seemed like the group was spending a lot of energy on something that is like driving 60 MPH in a 55 zone.

On 6/21/2018 7:22 PM, ajparent1/KB1GMX wrote:
Howard,

The mixer where the spur is generated is the mixer formed by T2/T3 that is about 
28db (after allowing for filter losses and all)  later in the stream and if that mixer
is overloaded you get the spur.  The driving modulator is then underdriven.

Work it backward.  If that mixer is overloaded at -7 oir -10DBM what got to be
happening well before that?   And that mixer can easily be driven to its 1DB
compression or worse without hurting the audio to the ear.

Allison


Join BITX20@groups.io to automatically receive all group messages.