[TowerTalk] RFI From SDA 100 Controller and PSU

Jim Brown k9yc at audiosystemsgroup.com
Mon Nov 25 18:04:15 EST 2013

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 

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

More information about the TowerTalk mailing list