"Lostgallifreyan" wrote in message
. ..
Lostgallifreyan wrote in
:

He wrote that. I didn't.

Sorry amdx, potential for confusion there... I mean the guy who wrote what
you linked to...

The Sangean ATS-909 along with similar radios are designed to resolve
signals from the whip antenna or in built ferrite antenna. Attaching 8 to 10
feet of wire to the whip will bring in more stations but depending on
location may well pick up so much extra signal as to cause intermodulation
and AGC limiting preventing reception of the weak signals you want to
receive.

As stated earlier, the front end of these receivers is wide open and the
front end is exposed to the complete spectrum of transmissions received by
the antenna.

There is nothing inherently wrong with the receiving system you have decided
upon but it will undoubtably overload your receiver with signals and you
will be puzzled as to why the reception seems poorer with more noise pickup
rather than less.

As Richard has stated you need some form of preselection to filter out the
unwanted signals before they get into your radio. Basically this is a
tuneable filter which only allows through a single band of frequencies at a
time. The following site explains the essentials.

http://www.dxing.com/tnotes/tnote07.pdf

You can buy commercial preselectors but they will probably cost as much as
your radio. As they are generally passive devices built from a set of
switched coils and a variable capacitor they last forever and old ones do
come up from time to time at junk sales and the like. It is possible to make
a simple filter to cover just one or two bands that interest you.

By all means, try the external antenna system but be prepared to buy a
'better' receiver with front end band pass filters or a preselector.

You can have too much of a good thing when it comes to receiving antennas. A
bigger receiving antenna won't bring in signals from further away. If they
are there, the receiver is probably sufficiently sensitive to pick them up
already. What the bigger antenna will do is raise the level of all the
signals it is picking up and feeding into the receiver and that includes
noise, and other unwanted stations. That is why you need additional
filtering to cut down the unwanted signals and allow your receiver a fair
chance of demodulating what you actually want to hear.

Regards

Mike G0ULI