[Discuss-gnuradio] using 2nd Basic-RX board ?

[cswiger]

This should be simple: a 2nd basic-RX board plugged into J668
works with a siggen, and scope w/ mux=0xf0f0f0f2, nchannels = 2
shows adc0 and adc2 A-OK. So the hardware is working fine.

But when I try to use it in my script I get a flatline:

        # setup usrp
        decim = 64
        self.dut_out = usrp.source_c(0, decim, 4, gru.hexint(0xf0f2f1f0),
0)
        self.dut_out.set_rx_freq(0,-self.f_ducddc)
        self.dut_out.set_rx_freq(1,-self.f_ducddc)
        self.dut_out.set_rx_freq(2,-self.f_ducddc)
        rx_error = -self.f_ducddc - self.dut_out.rx_freq(0)
        self.dut_out.set_pga(0,8)
        self.dut_out.set_pga(1,0)
        self.dut_out.set_pga(2,0)

        head = gr.stream_to_streams(gr.sizeof_gr_complex,4)
        self.fg.connect(self.dut_out,head)

(head, 0) sources what J19 on the 1st board sees, (head, 1)
sources what J18 see, but (head, 2) is zeros, flat, nothing.
Am I missing a setup option on the 2nd RX board?

There's a signal generator running too if that matters:

        # signal generator
        self.interp = 128
        self.type = gr.GR_SIN_WAVE
        self.offset = 0
        self.nchannels = 1
        self.mux = 0x0098

        self.sg = usrp_siggen.siggen ()
        self.sg.set_waveform_ampl (self.amplitude)
        self.sg.set_waveform_freq (-275e3)
        self.sg.set_interpolator (self.interp)
        self.sg.set_waveform_type (self.type)
        self.sg.set_waveform_offset (self.offset)
        self.sg.set_duc_freq (self.f_ducddc)
        self.sg.usrp.set_nchannels (self.nchannels)
        self.sg.usrp.set_mux (self.mux)
        self.sg.fg.start ()


Follow up academic question: If you can have 1 usrp.source_c stream, why
not 3 ?

TIA

--Chuck