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AD9746 + SDP-H1: temperature performances & bandwidth


I am currently using AD9746 eval board and SDP-H1 for measuring performances of AD9746 in the following conditions:

     - Output signal on IOUT1P: level of -1 dBFS and frequency from DC to 40 MHz

     - IOUT1N is ground for common mode measurement.

     - External clock frequency injected in J1: -2 dBm / 100 MHz


I have to perform several measurements:

     - Bandwidth from DC to 40 MHz at -30, +25 and +50 °C

     - SFDR, Harmonics, NSD, output power (among others) at above temperatures at the following output frequencies: 10 kHz, 10 MHz and 40 MHz

My issues:

     - Issue 1: for temperatures from 0°C down to -30°C, output power starts to decrease and spurious ans noise level increase. 

Question 1:  Does AD9746 + SDP-H1 can be used for tests in temperature?

     - Issue 2: DAC output power starts to decrease below few MHz. For instance, I get an attenuation around 35 dB by comparing output signal generated at 10 MHz compare to signal generated at 10 kHz.

Note: the balun (T5 and T7) of AD9746 eval board have been shorted. Additionally I have also tested to tie R34 and R36 to AVDD33 as proposed within AD9746 datasheet.

Question 2: what is DAC output bandwidth?

Thanks a lot for your help. Do not hesitate if you need more information.