[Elecraft] RFI resistant Monitor

[Jim Brown]

In the tutorial at the link posted, I wrote:

Evaluating Equipment For Noise: When someone tells you that XYZ 
equipment produces no noise on the ham bands because he can’t hear any 
noise in his radio, should you believe that the equipment is clean? NO! 
The equipment may be noisy but is not heard because it is being covered 
by other noise from the neighborhood. Figs 7 and 8 compare the daytime 
80M spectra at K6GFJ in a San Jose residential neighborhood and K9YC 30 
miles to the south in the Santa Cruz Mountains. The difference in the 
noise floor is 10 dB. And it’s certainly not dead quiet in the 
mountains, either – everything on the displays from both QTHs is noise 
from either switching power supplies or other electronic sources.
Proximity to Antennas Is What Matters:  Noise radiates from sources on 
wires that are connected to noise sources, and enters our receivers via 
our antennas. My SteppIR that’s up 120 ft and is 200 ft from the shack 
doesn’t hear much noise from the shack, but the 160M Tee vertical only 
25 ft from the operating position does. When someone tells you that a 
particular model of internet router or video monitor sits next to his 
power amp and there’s no RFI, ask him how far it is from his antennas, 
not from his radio.

73, Jim K9YC

On Mon,4/11/2016 7:43 AM, Jim Sheldon wrote:
> The switcher supplies for these 2 monitors appear to be virtually 
> noise free.  At least I have not had any noise problems that I can 
> attribute to them and they have been on the desk for several years now.
>
> My major noise source has always been the 7500 volt power lines that 
> run across the South and West sides of my small city lot. Fortunately 
> the utility company ran afoul of the FCC several years ago and they 
> are very responsive to noise/interference calls.