17
14. Set field strength (6) to -3dB to 0dB at the peaks. If Peak (8) LED flickers only
momentarily the connection is acceptable. If Peak LED indicates continuously, try
rewireing the connections in the junction box in subsequent order: II) single 1-turn and
then III) 1-turn in parallel
.
With this procedure the unit will operate with the highest output possible without
generating excessive heat.
Note 1
To quickly set up the field strength for a real program source, a PPM instrument
is helpful. The Univox Listener has a calibrated level indicator that quickly finds the
highest peak.
Note 2
When adjusting the field strength peaks, -2dB field strength works best, due to
different dynamic headrooms in hearing aids.
15. Check basic frequency response according to IEC 60118-4, using a field strength meter,
e.g FSM 2.0. If necessary, follow Frequency adjustment procedure (see page 12).
16. Check the sound quality by using an external listening device (Listener or FSM 2.0),
Monitor speaker connector (14) or Monitor (9) for headphone (volume control on rear
panel Monitor (13)). When operating at maximum output on low impedance, i.e single
turn loops, the automatic limit protection circuit may cut programme peaks. This can
be avoided by changing to a 2-turn loop or reduce the output current setting.
17. Start the Commissioning process to certify the installation (see page 18).
