wrote in message
oups.com...
Ron Baker, Pluralitas! wrote:
Hmm. I see your receiver is portable. Maybe walk or drive
around the area and see if the signal strength varies.
Maybe try a directional antenna in order to locate the source.

Well, I've done a bit of driving around the area, ableit with the whip
on the antenna. I think I've traced the source to a number of antennae
on top of a nearby tower block. Parked underneath it there is very
little signal, however within direct sight of these antennae there is
a continuous high-pitched tone. As I move further away from this in
any direction this gets weaker and eventually peters out. The broken
sound I recorded still exists over most of the region when the
continuous tone is unnoticeable.

I wonder if they have the same source then.


I'm going to put the problems down to something on top of this block.
There are mobile phone transmitters on there, that I know, and another
long whip which could be UHF or VHF. I haven't looked into what effect
this is having on FM or AM radio so I will have another trip up there
soon. However it doesn't affect me from the flat. I also made a point
of driving near a number of mobile transmitters and they don't have an
effect on the scanner.

It's good to eliminate possibilities too.


I've got an airband filter on order, hopefully this might clear up
some of the noise but whatever it is I guess won't be completely
legitimate...


If it it an image response by your receiver that should
work.

A dipole is a directional antenna. Not as directional as some
but a dipole is easy to make. At 130 MHz a half wave dipole
would be a little more than a meter long.
But I hope the filter works for you.

--
rb