On 22 Oct 2005 11:06:03 -0700, said in
rec.radio.scanner:

I'm looking for a rough idea of how much the following options would
improve my reception experience against the cost / difficulty of
completing those changes:

1) Change aerial (must also be able to Rx & Tx on 2m and 70cm)

Not much change, since the antenna is really a random length (and a
short one) or wire at aircraft frequencies. Cost for a significantly
better antenna - significant.

2) Raise aerial by 1m or so, so that it is above neighbours roofs.

Not much difference. See below. Cost - relatively little.

3) Change aerial feed cable

Unless the cable is really bad, 7 meters of cable isn't going to have
too much loss at 100 MHz. Cost - relatively small.

4) Ground the lightening arrestor (something I know I need to do
anyway)

If a lot of your noise is from static on the antenna, this may help a
bit. Ground the antenna for a moment and see if the noise goes away
for at least a minute or two. Cost - almost none.

5) Change Rx end BNC to BNC cable (is that the right kind of cable?
Impedance mismatch?)

What's "BNC cable"?

6) Change panel mount BNC connector (does this let noise in due to
short unshielded bit of inner cable or impedance mismatch?)

What's the panel connector now?

7) Add a band pass filter for airband at the Rx end

Noise is broad-band - it's on the aircraft band too. Cost -
relatively high.

8) Add a pre-amp for airband as close to the aerial as possible

It'll probably increase the noise as much as it increases the signal.
Cost for a good one - very high.

Any other suggestions?

1) Be aware of what kind of system you're trying to receive. The
aircraft communications system is designed for 3 things:

a) air to ground communications
b) ground to air communications
c) air to air communications

One thing it's *NOT* designed for, except ar extremely close range, is
ground to ground communications. (The tower can see the aircraft on
the ground. Can you?) Unless you're within a km or 2 of the airport,
concentrate on receiving aircraft that are a) not too high up and b)
near you. Very few people have the equipment to DX aircraft signals.

2) Your receiver's AM detector may not be as good as an AM detector
can be.