On 12/19/2010 9:42 AM, dave wrote:

...
The antenna on a good portable is an active. It must be shorter than 1/4
wave at the highest frequency of interest to work at its optimum.

The EXT jack on a 7600 should be able to handle a proper wire antenna
10m or so.

On 12/19/2010 2:42 PM, John Smith wrote:

Physics is certain on this point. An antenna with a larger capture area
will always capture a stronger signal ... arguing that is pointless.

Regards,
JS

But nobody is arguing that.

NOT "pointless"; rather it is exactly the point.

Field strength is measured in volts per meter or micro volts per meter
(of antenna length).

Nobody is denying the point that you are locked in on, namely that a
longer antenna will give a stronger signal. This is indeed true...but it
is also THE PROBLEM (with the receiver specified by the OP).

The stronger signal from the longer antenna will overload the front end
of the receiver in question. THAT is the problem. And no, a down stream
(IF filter) is not the answer. Due to the front end overload, the signal
reaching the IF filter will -already- be damaged.

To anticipate your next response -- use of an attenuator -- will indeed
alleviate the problem. But just think for a minute: What is the point of
building a longer antenna to get a stronger signal that you are just
going to attenuate anyway.

Best regards and happy holidays,
Joe