439.990 deliberate interference?

[VK5 Admin]

It was happening on the Sunday broadcast too during callbacks. Lucky no one acknowledged it and they just went away probably thinking they weren't getting through.

[VK5TOM]

Yeah theres been stuff happening like that on the other repeaters too

[VK5KKS]

I monitor the 439.900mhz repeater and every now and then it sounds like some clown comes up and hits the PTT a half a dozen times. This is a regular thing so I wonder, is it an idiot or is there something else happening?