[hpsdr] Odyssey SDR Rev. B Schematics

[Ahti Aintila]

> Steven Bible wrote:
> > ***** High Performance Software Defined Radio Discussion List *****

> > In the background, I've been working with Ahti's OH2RZ ISD design (which is a progression of Bob N4HY and Phil C's N8VB ISD work - see schematics on the HPSDR SVN and Phil's Blog).  The goal of this circuitry is to design a fully differential circuit for input (ISD) and output (exciter) to create a low-noise circuit and also to get to a signal power supply.  The input (ISD) follows Ahti's work.  I've made a few additions to Ahti's work after reading a number of application notes, and to add a few extra components that we can use at the time of testing (a follow up PCB would be designed from the lessons learned from this board).  We've already had a short discussion of this about a month ago on the HPSDR list (see HPSDR archives).
> >
Steve,

Good work you have done!  The SN74LVC2G53 is really a better choice
for the sampling switch. Then you have a possibility of using 5 V
supply for higher dynamic range. You possibly need to put some small
resistors (or "damped" inductors) in the place of R3, R8, R15 and R18.
Together with the capacitance between pins 1 and 8 of the OPA1632D
they will attenuate the switching spikes and improve the transient
intermodulation distortion values. This same applies to R23, R28, R35
and R38 in the QSE circuit because the output of the OPA1632 does not
"like"quickly swithed low impedance loads.

73, Ahti OH2RZ

> > _______________________________________________
> > HPSDR Discussion List
> > To post msg: hpsdr at hpsdr.org
> > Subscription help: http://lists.hpsdr.org/listinfo.cgi/hpsdr-hpsdr.org
> > HPSDR web page: http://hpsdr.org
> > Archives: http://lists.hpsdr.org/pipermail/hpsdr-hpsdr.org/
> >
> >
>
>
> --
> Robert W. McGwier, Ph.D.
> Center for Communications Research
> 805 Bunn Drive
> Princeton, NJ 08540
> (609)-924-4600
> (sig required by employer)
>
>
> _______________________________________________
> HPSDR Discussion List
> To post msg: hpsdr at hpsdr.org
> Subscription help: http://lists.hpsdr.org/listinfo.cgi/hpsdr-hpsdr.org
> HPSDR web page: http://hpsdr.org
> Archives: http://lists.hpsdr.org/pipermail/hpsdr-hpsdr.org/
>

 1162235236.0