Re: ubitx - stop press

Jerry Gaffke
 

Off topic, just feeling my way through on this specan stuff.  

The AD8310 is spec'd for a maximum input of +/- 2 volts pk-to-pk, or 4 dBV.  So I'd want at least enough gain after my level 7 mixer to be able to drive the AD8310 to that maximum without having appreciable distortion crop up in the mixer.   That should give the instrument the 95dB dynamic range available from the AD8310.

More gain than that is a good thing, allows us to see lower level signals.  Can always use a step attenuator when looking at large signals.  But at some point the front end is generating enough noise that more gain does not buy anything.

Correct me if I've missed something here.



On Sat, Apr 8, 2017 at 06:50 am, Jerry Gaffke wrote:

really have to build a basic spectrum analyzer.   Perhaps just an Si5351 breakout board, a 50mhz lowpass filter, a level 7 mixer, a PX1002 86.85mhz SAW filter, an MMIC gain stage, and an AD8310 into a Nano's ADC.    Or do I need more gain stages for this to be useful?

 

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