I recently tore down and remodeled my shack. When I put things back together, I repositioned just about everything, including eliminating a couple of unnecessary power supplies. During this process, I decided to power the MFJ-1026 Noise canceller to a small switching power supply. This noise canceller is used with both the main Alpha Delta DX-CC multiband dipole and a receive loop run around the yard to help phase out local noise sources on the lower bands.
I thought I blew up the MFJ-1026 by running legal limit too close to the receive loop because all I could hear was static, noise, high pitched whine, etc., so I took it out of line and put it on the shelf. Fast forward a couple of months and I purchased a W6LVP Magnetic Receive loop. During a temporary install of the mag loop, I noted the instructions said to only use the supplied 12v power supply and never use a switching power supply as it will inject noise into the RX signal. A light bulb when on and I put the MFJ-1026 back in line, powered by a simple 12v motorcycle battery. The RX was perfectly clean on the original RX loop and the noise canceller worked exactly as expected. So then I hooked it up into a linear power supply with the same result. The entire time it was "malfunctioning" was due to the switching power supply I had plugged it into.
Lesson learned: NEVER use a switching power supply to provide power to an amplified RX antenna!
I thought I blew up the MFJ-1026 by running legal limit too close to the receive loop because all I could hear was static, noise, high pitched whine, etc., so I took it out of line and put it on the shelf. Fast forward a couple of months and I purchased a W6LVP Magnetic Receive loop. During a temporary install of the mag loop, I noted the instructions said to only use the supplied 12v power supply and never use a switching power supply as it will inject noise into the RX signal. A light bulb when on and I put the MFJ-1026 back in line, powered by a simple 12v motorcycle battery. The RX was perfectly clean on the original RX loop and the noise canceller worked exactly as expected. So then I hooked it up into a linear power supply with the same result. The entire time it was "malfunctioning" was due to the switching power supply I had plugged it into.
Lesson learned: NEVER use a switching power supply to provide power to an amplified RX antenna!