Two more of my local friends (W6GJB and W6OAT) have narrowed down severe
RF noise to their SDA100 controller. The PSU, a VERY noisy switching
PSU, is the major offender, but the controller itself also puts out some
noise.
If you are experiencing RF noise, turn off your SDA100, unplug the PSU
from the AC line, and listen carefully on all bands. You'll need to tune
the SteppIR to each band, one at a time, before powering down the
controller. If you SteppIR is a beam and far from the shack, point it
directly to the shack before doing your tests.
SteppIR send me a relatively quieter replacement for my 33V supply, but
I still heard it on antennas that are close to my shack (especially on
160M), so I've gone back to a vintage home brew linear regulated power
supply that I bought from the estate of a neighbor ham. That PSU, of
course, is dead quiet, but I still hear noise on 160M on the vertical
that's right outside the shack. Hence, when I'm on 160M, I have to kill
power to the SDA100.
73, Jim K9YC
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