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oups.com...
Hi

I would like to improve my airband reception for my local airfield
(Sywell). Currently I can hardly make out what the tower is saying and
struggle with 75% of aircraft as the voice signal levels dissappear
into the noise levels. Most signals do activate the squelch ok, but
the audio noise levels are just to high.

My current setup consist of a dual band (2m & 70cm) vertical fiber
glass antenna (I can't find the exact details at the mo) on a 2.5m
meter pole which takes the top of the aerial just above level with the
neighbouring houses roofs. It then feeds into the loft with about 3 M
of Y[1] cable, through a small lightening discharge unit (which I still
need to put the ground connection in for) and then through 3m meters
more of Y[1] cable. Then inside the loft room it goes into a panel
mount BNC connector and through 1M of RG-59/U cable before going into
the AOR AR900 scanner.

[1] It has no numbers written on it, but it is a 1cm diameter coax
cable
original bought for amateur radio use.

I suspect the loft room is fairly RF noisy as it is my study including
two computers, monitors, ADSL, wireless 802.11b etc. Connecting the
scanner to mains (via it's transformer, or battery makes no difference.

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)
2) Raise aerial by 1m or so, so that it is above neighbours roofs.
3) Change aerial feed cable
4) Ground the lightening arrestor (something I know I need to do
anyway)
5) Change Rx end BNC to BNC cable (is that the right kind of cable?
Impedance mismatch?)
6) Change panel mount BNC connector (does this let noise in due to
short unshielded bit of inner cable or impedance mismatch?)
7) Add a band pass filter for airband at the Rx end
8) Add a pre-amp for airband as close to the aerial as possible

Any other suggestions?

Thanks in advance
Kev



Just out of curiosity, you say the aircraft on the ground are noisy and the
tower too. Are aircraft in the circuit area ok and readable or are ALL
affected?
Silly question, but you are in AM Mode, aren't you?
The antenna you have is not designed for this frequency range, but ought to
work well enough as I am able to listen to aircraft on a similar
arrangement.
Further height will always help, especially as you want to hear ground
signals. It will make little difference with airborne signals.
If oyu are having trouble with ALL aircraft signals, then you really need to
consider relocating that antenna. Consider turning off some of that
equipment to isolate the possible noise source that may be drowning them
out.
If the signals are affected by local noise, a preamp will amplify that too.
Putting an airband preamp on won't allow you to use it for 2m and 70cm.
I don't understand the part about "short unshielded bit". None of the coax
or bnc plugs should allow you to have any "short unshielded bits" and might
be a starting point.
Grounding the lightning arrestor should make no difference to reception,
only offer protection in the event of a local discharge, and it won't do
much in the event of a direct hit, so don't place too much faith in it.

Brad.