[DSP-10] Hissing Noise

[Matthew J. Wolf]

First off, I do not have that much experance trouble shooting electronics.

I have a problem with my DSP-10. When ever the DAC lines are connected to the RF board, I get a hissing noise coming some where on the RF board. The hissing gets lounder as the AF gain is raised. The hissing noise is also present when only one of the DAC lines are connected.

Where should I look for the issue and or is there any good books that would help me under stand what may be happening?

-Thank You
   Matthew Wolf, N9MTT