Re: [Discuss-gnuradio] Max Voltage swing for WBX boards

[Jason Abele]

On Tue, Sep 14, 2010 at 9:24 AM, Vincent W <address@hidden> wrote:
> Hi,
>
> I'm trying to do some signal reconstruction and in testing and developing a
> concept design, I wanted to attenuate a test signal and hook it up directly to
> the RX port of my USRP2 through either the Basic RX or LFRX daughter board 
> (and,
> eventually through my WBX board). My intention was to attenuate the signal
> through either a resistive attenuator or inductively through a transformer.
>
> Essentially, I want to temporarily use my USRP2 and boards as an oscilloscope.
> I'm very aware that I need to be _really_ careful doing this, as it would be
> _very_ easy to break something.
>
> Theoretically though, provided I can guarantee my signal falls within the
> accepted input voltage swing for a given daughter board, there shouldn't be 
> any
> problems.
>
> A couple of questions then:
>
> What are the absolute and preferred input voltage ranges for the RX, LFRX, and
> WBX boards?

BasicRX or LFRX can take +10dBm (~2Vpp)

WBX input power should not exceed -10dBm (~0.2Vpp)

>
> Has anybody successfully tried this?
>
> What are the dangers I should be looking out for?
>
> Are there specific precautions I should be taking?
>
> What is the best way of attenuating the signal?

Mini Circuits makes a line of coaxial attenuators which can be
installed in your SMA cabling, we find they work fairly well.  I have
also found the the North Hills baluns to be very nice, as well as
those from Mini Circuits.

Jason