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Choosing and connecting an antenna
Attention: Transmitting without having an antenna connected would result in a destruction
of your radio set!
The antenna is an important component of the radio equipment and has a major impact on the
reach of the radio set. Depending on the intended usage of the radio set, different antenna types
are available your specialist dealer will be happy to advise you!
Antennas for stationary radio sets
When using a stationary antenna, the maximum range of your radio set is achieved. However
when installing outside antennas, various provisions (lightning protection, German VDE) have
to be observed: We recommend you to have the antenna system installed by an expert!
Mobile antennas
A distinction is made between tuned and tunable mobile antennas.
Tuned antennas should only be mounted on a great metallic surface (e.g. on the roof of the vehicle
or the trunk lid) assuring a short connection to ground. For an antenna which must be fixed by
drilling a hole into the car body, the body sheet must be thoroughly smoothed until metallically
bright for assuring a good ground connection. Furthermore, make sure not to bend any cables
or connecting lines and not to install them on sharp edges or along vehicle components which
get hot. Connect the antenna cable to jack (B).
Tunable antennas are to be adjusted to the output resistance of the transmitter (50 ohms). The
actual characteristic antenna impedance depends on its length and on its environment of installation.
For this reason, the manufacturer can only provide you with a roughly tuned antenna. Normally
it is designed such that there is always enough scope left for adjusting it to the given conditions.
In practical operation, this means that a new antenna is usually too long.
For adjusting the antenna, connect a VSWR resistance bridge (e.g. President TOS-1, article no.
50004) into the circuit between the radio set and the antenna. Set the radio set to FM modulation
to work always with a constant transmitting power when measuring. Adapt the antenna according
to the manufacturers information such that the VSWR on your preferred channel or one of the
median channels approximates to 1: A value of 1.5 is still acceptable. (For mobile operation, it
does not make much sense to adjust a value of 1:1 by all means, since this value is modified
again due to different environments, cable modifications etc.) Regularly check the antenna
adjustment: An unfavorable value points to connector and cable problems!
A
DC-power connector (13,2 V)
B
antenna connector (SO-239)
C
external speaker jack (8
W
, Ø
3.5 mm)
