On 2007-09-19 14:43:50 +0100, "Dave Plowman (News)"
said:

In article ,
Andy Hall wrote:
So either the DA is faulty - although it appears to be increasing the
signal level - or one of the tuners is *transmitting* a nasty back up
the line?

I'm rather lost with RF. ;-)

I had one at one point that developed some fault that caused it to
start oscillating at around 350MHz. The net result was that there was
a lot of apparent noise and crud on FM and again on the lower channels
of UHF (i.e. Crystal Palace). Higher UHF channels were OK. It
took an installer with a rectum paralyser (sorry spectrum analyser) to
detect this. Amplifier was swapped and all was well.

If one of the tuners is doing something, then turning devices off in
sequence should find it.

I'm wondering if the DA itself is hooting. Not got anything here that can
check those sort of frequencies. My 'scope does go up to 100 megs, but
I'd not know what to look for. It does show noise with the input
shorted, though.

Exactly.

I don't have the high signal issues that Tony alluded to - it was the
DA that was taking off. This was creating wideband crap as well as
interference but also it was still kind of working. Of course it
may have been that it was providing no gain as opposed to some gain.