Good Morning everyone.
I have posted two more photos to the N1RX folder. These show
the "noise spike" at the center frequency of a SoftRock-40. One
shows the spectra obtained when the SR-40 is powered in the original
fashion, from the USB port of the computer. This uses the original
Q1 power filter circuit. The second photo shows the EXACT SAME SR-
40, powered by bringing in external 5v, derived from a battery
supply, using a 78L05 regulator.
In both cases, the radio is operating on 40M, connected to a dipole
antenna. The only change between the two was to unplug the card from
the USB port, and connect the external power source using a couple
of clip leads. It is clear that better performance can be obtained
by using a seperate source of power for the SoftRock.
For details on how to modify the SoftRock for non-computer power,
see the appropriate photos in the N1RX folder.
73,
Bruce N1RX
