[RFI] RFI-Free LED Monitor Recommendation

[Jim Brown]

On 1/21/2021 6:38 AM, N8GLS wrote:
>   All
> are no more than 2 inches above the rigs and they don't produce anything of
> concern on HF, VHF or UHF.  See my QRZ.com page for a look at the layout.

It's not proximity to rigs, it's proximity to antennas. And whether you 
hear them depends a lot on how much other noise you and your neighbors 
are generating with SMPS, variable-speed motor controllers, and other 
electronics. The stuff in your station should not pick up noise from 
sources in the shack unless they are poorly bonded.

The larger the display, the higher the voltage of the power supply it 
uses. 3-5 years ago, I and some other local hams bought a half dozen or 
so 23-in Samsung LCDs that run on a nominal 14VDC, and that are quite 
happy with 12VDC. Their SMPS units are noisy pigs, and the video feed 
can add a bit of noise to nearby antennas on some bands. It's easy to 
replace the SMPS with a vintage linear wall wort, even an float-charged 
12V battery added to act as a UPS. Noise from video cable can be killed 
with a suitable #31 choke.

Unfortunately, those models are history. It is, however, good to poke 
around mfrs websites studying data sheets and photos of back panels to 
learn what DC voltage they use. Last time I looked (a year or two ago), 
I found relatively low-spec LCD monitors or receivers in the 22-23-in 
size range designed for 14VDC.

And don't assume that a given brand will be free of RFI. 6-8 years ago, 
a friend gifted me with a 23-in Samsung touchscreen LCD because it went 
nuts when I transmitted on nearby antennas. Worked the same here, but 
was also a noisy pig, even running from a linear supply. I re-gifted it.

73, Jim K9YC