Setting up an aerial in the loft
Where no field strength meter is available the easiest way is to have a receiver
in the loft so that you are listening to the final result and can align more
readily. Hold the aerial from the rear to avoid multipath from your person.
Wind Noise
Depending on building construction and wind direction, some arraays can cause a "tuning fork" type of
vibration. This can be minimised using self amalgamating rubber tape when assembling the array. Wind two
or three turns either side of the centre hole of each element. If this is insufficient, pairs of elements
can be taped together, close to the aerial frame. This is quite effective but not very neat. Another source
can be the open ends of the aerial mast which can be blocked. Also S.A. tape between "V" bolts and bracket
can help
Guylining
Guylines can be dangerous where children run and play but they do secure taller arrays. They should be run
either in a 60 degree "Y" or 90 degree "X" configuration for maximum strength. Various tensioners are
available but "claw" type strainers are best as they have no moving parts and can be re-used. They can also
be really tightened, using a "t" bar type tool. The "bottle" type which use opposite threads to lengthen
or shorten the "bottle" always rust solid if left unattended. for extended periods. Galvanised strainer wire
should be used and checked for any corrosion at intervals, and retensioned or replaced as necessary.
Amplifiers or Boosters
Unless a signal is to be split to numerous outlets, these can be counter productive as the device can only
amplify what it sees."Rubbish in equals rubbish out" is fairly accurate. The only way to improve the signal
is aerial design and optimum height. The cable between the actual aerial and the receiver is critical and
should be at least double screened low loss with airspaced dielectric. If the cable exceeds say 40 metres
a high quality low noise amplifier close to the aerial can help. Many purists won't countenance amplifiers,
but where many outlets are required at any one time they cannot really be avoided. Where only two points are
to be fed, it can be practical to fit a coaxial switch with coaxial outlets so that a temporary "y" splitter can be inserted for the occasional dual use.
Full Listing of AM, FM, and DAB radio stations is available from:
P.D.Q.Publishing, P.O. Box 888, Plymouth, PL8 1YJ
Tel: 01752 872888. They do separate magazines for TV and Radio.