[Elecraft] K3 & Plasma Question

[Ron D'Eau Claire]

Anytime there is high-speed digital logic in operation there is RFI being
generated. After all, those "logic" signals are no different from a square
wave RF signal, and being square waves means they have very high levels of
harmonic energy across the spectrum. 

The big difference is that a plasma panel generates high-energy RFI directly
in the display which then radiates it through the screen.

As you noted, the level of RFI will be much lower with LCD sets and, in many
cases, can be suppressed further with proper treatment of the various wires
leading to and from the set. 

73, Ron AC7AC

-----Original Message-----
I also had a Plasma TV, a 42 inch Visio purchased many years ago, and had
the terrible RFI problem on 80 meters especially. My 80 meter dipole hangs
across the house , one leg over the plasma. I never operated much in the
lower bands where the RFI was worse, but figured I would eventually get a
LCD or LED TV and the problem would go away. 

Well, the day came and I was itching to get a larger screen TV. I saw
another Visio (they have good clear displays), so I thought I would opt for
a LCD 55 incher. i had forgotten about the RFI problem with the plasma, but
heck, this is a LCD so it should not have any problem. I got it home and
really liked it.  Well, as you might expect, I was on 80 meters working some
CW one night and on the P3, I saw these little spikes, maybe 160 KHz apart
(-85 dBm +/- a few dB). I hollered at my wife to turn off the TV and well,
you guessed it, the spikes went away. 

So, in my case, an LCD TV does have some RFI, although not as much as the
plasma. Interesting, a 32 inch LCD Visio in the shack has no RFI  as best I
can tell and the dipole goes directly over the shack.



-----
Roger W5RDW
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