[TowerTalk] RFI From SteppIR SDA100 Controller

[Jim Brown]

I've been chasing a very strong, very elusive set of drifting birdies. 
They were strongest on 12M, but also were present on 15M and 10M.  
Nothing affected them until I unplugged the power supply for the SDA100, 
at which time they went away, and the overall noise on the band dropped 
by at least 10dB.   This crap radiates  into every antenna I've got.

I've managed to attenuate this crap by at least 20 dB using chokes on 
the cable that runs to the antenna, the rotor cable, and both the 120VAC 
and 33VDC cables from the power supply.

If you've got an SDA100 (that's the newer, higher voltage controller), 
you might want to check this.  15dB is a LOT!  The best way to see 
what's going on is with a panadapter set pretty wide so that you see 
birdies drifting slowly up and down. I'm using a P3.

73, Jim K9YC