Hi All,
I wonder if anyone can tell me what their HiQSDR noise floor is, when the input is not connected (or connected to a dummy load)? I have the impression that the noise floor of my HiQSDR board is rather high, hence I ran a few tests. I tuned Quisk to 10.7 MHz and provided a signal of -80 dBm, which showed as -77 dBm on the S-meter in a bandwidth of 3 kHz. Hence, the signal strength of the S-meter correlates well with the applied signal. The signal strength of the noise in a 3 kHz bandwidth showed a value of -101 dB(m). Ignoring the 3 dB difference, a noise floor of -101 dBm in 3 kHz equals a noise figure of approximately 38 dB! Given the hardware build up I would expect a noise figure somewhere between 20 and 30 dB, but I have not been able to find any specifications of the HiQSDR hardware which shows such specifications. So before I start debugging the HiQSDR board for anything faulty components, I wonder if anyone can provide reference noise levels (or noise figures)?
BTW, I checked also on 4 MHz, and the noise floor drops 1.5 dB in 3 kHz bandwidth (i.e.: 102.5 dBm).
I set the attenuator in Quisk to 0 dB, the positive Gain setting never worked.? ??
73s,
Peter, PA3BIY
