Sennheiser SKM 500, Manual, Page: 89 / 204

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9 Overview
Wireless transmission systems
With the evolution wireless series, Sennheiser puts an end to cable tangles
and enables complete freedom of movement at an affordable price.
The systems operate exclusively in the UHF band. UHF transmission is
extremely reliable and is far less prone to interference than the overcrowded
VHF band – harmonics from mains units, fluorescent tubes, refrigerators,
computers, etc. are virtually eliminated. Also indoor propagation of UHF
radio waves is better than VHF so that the RF power can be kept low – this
is also an advantage when using multi-channel systems. Finally, UHF
frequency ranges are being approved all over the world for radiomicrophone
usage – in some countries licence-free.
There are three transmitter versions: The hand-held transmitter is a
complete radiomicrophone in a single unit, the plug-on transmitter converts
your favourite wired microphone into a radiomicrophone (and, with its built-
in 48V phantom power, can even power condenser microphones), the
pocket
transmitter can accept a wide range of inputs including: omni-directional or
cardioid “tie” microphones, head-worn microphone, guitar/instrument direct
input and auxiliary devices via the optional CL 2 line input cable.
Fresh batteries ensure good transmission power during operation. Always
use alkaline batteries for best operation – a 9 V PP3 battery has a much
longer operating time than a NiCd rechargeable battery (approx. 8 hours
with a 9 V PP3 or 1 hour with a rechargeable).
Correct adjustment of transmitter sensitivity is vital. Too high and you get
overmodulation and distortion, too low and you get undermodulation and a
noisy signal. Please set the sensitivity correctly for the microphone/usage
and check it before every performance to ensure best operation.
Sennheiser miniature clip-on microphones can be attached in various ways:
they can, for example, be attached to the hairline or to clothing (e.g. tie or
lapel). However it is fixed, please make sure that the microphone is protected
against sweat/moisture and make-up.
Interference such as distortion, hissing or “birdying” may occur if several
transmitters are used together and the frequencies have not been correctly
chosen. Sennheiser standard frequencies (as supplied) are all intermodulation-
free. For other frequency sets please contact your local Sennheiser agent,
who will be able to provide you with information on correct frequency choice
and/or be able to calculate special frequency sets for you.