Jo 90 – 20 hours ago  » 

Just set the Humax box up on another TV,

No message now, so it looks like the problem is possibly the ariel feed on the other TV?

Anyone?

I think you have demonstrated that the problem is with that aerial feed. I think you said you have a four way amplifier but are using only three of the outlets. Try connecting the problem feed to the unused output and see if that fixes the problem. If it doesn’t then you need to examine the run of the aerial cable to see if there is anywhere that the voltage is being injected. Also it might help if you could give us the model number of the SLX.

Thanks. The user manual suggests that the SLx can supply power to a masthead amplifier but the power would be on the aerial in socket. https://www.philex.com/products/wp-content/uploads/2016/10/27820R-4-way-Aerial-distribution-amplifier.pdf Does that throw any light on the problem?