Adrian wrote:

I went from a single PC to a double PC setup last year, and went for a
HDMI KVM so that I didn't have to get a second monitor/keyboard/mouse.
Ever since then I've had a problem with receiving most of the TV
channels that I get via Freeview

HDMI is sometimes known to interfere at UHF frequencies (depending on
resolution and pixel clock) how close is the KVM to any part of your TV
wiring?

I've never seen it from DP despite having a tuner card in one of the KVM
connected PCs and DP using even higher frequencies in the UHF range.