Introduction
Sonifex HY-03 User Handbook
3
The telephone line socket is connected to the telephone network using the cable provided (either RJ11 to RJ11, or RJ11 to
BT plug).
A simple telephone handset can be used to take and make calls when plugged into the equipment handset connector. An
adapter is provided if the handset is fitted with a BT plug as standard.
A remote switch may be connected at the Remotes socket in order to control the line connect switch from say, the telco
channel of a mixing desk.
Connect the output from the mixing desk “clean-feed” to the mic/line input of the HY-03, with the mic/line input select
switch set to “line input”. A clean-feed is a signal produced by a telco module on a mixer which is used as the output to be
fed back to a caller on a telephone line. The cleanfeed is a sum of all the other signals which constitute the programme
output, except for the caller’s audio (this is so that the caller doesn’t hear him/herself in the ear-piece). A cleanfeed signal
will generally be of a better quality than a mix-minus signal.
The characteristics of the mic/line input are determined by the state of the mic/line configuration selection switch. It is a
balanced bridging input and in line mode will accept normal signals at 0dBu peaking to +8dBu from a sound mixer clean -
feed. In mic mode the unit will accept 200 ohm microphone level signals with a maximum gain of 74dB. It is suitable for a
wide range of microphones and the available gain is 74dB to 40dB, which can be adjusted by the mic level pre-set
mounted on the rear panel. The input circuitry to the HY-03 has a very effective limiter, which will prevent high level
overloading problems. Ideally, the maximum input level should not 12dBu. This limiter is used for both line and
mic input modes.
The output connection will deliver a balanced/floating low impedance signal of 0dBm from the telephone line. The output
of the analogue hybrid unit is normally 0dBu from a balanced source of 50 ohms or less across the useful bandwidth of the
equipment. The bandwidth is restricted by the line conditions between 250 Hz and 4 kHz. The output stage is capable of
driving into 600 ohm loads at up to +8dBu. Termination of the output is not necessary however and direct connection can
be made into the mixer telephone return channel. The output stage has a gain pre-set control, mounted on the rear panel,
which may be set to give 0dB signals at the output. In addition an output noise gate operates when the telephone signal is
below the noise gate threshold control. This noise gate reduces the output gain by 34dB under no signal conditions
eliminating the affects of telephone line cross talk. The noise gate is factory set to –26dBu to avoid interaction with the
equipment null.
Isolation of better than 28dB is created between the input and output connectors when the hybrid unit is functioning on an
exchange line.
Note : The earth bond at the screw terminal must be connected to a technical earth to ensure the safe
operation of the equipment under all line conditions.
Using the HY-03
Receiving a Call
With the equipment connected as in Figure 1-4 calls may be received and detected by the ringer in the telephone handset.
To receive the call, lift the handset and establish contact with the caller. The call may be diverted to the telephone hybrid
by pressing either the front panel mounted line connect switch or by means of the remote divert switch (if connected).
Alternatively, the incoming calls can be answered automatically by enabling the integrated ringing detector. It is
recommended that the K-break line clearance is used when the ringing detector is enabled. When the ringing detector is in
use, ringing tone will illuminate the line connect switch. The line connect switch lamp is off in the non-connected mode and
illuminated in the connected mode.
Note : The remote lamp tally mimics the front panel line connect switch lamp, i.e. it flashes when ringing and
is on when the line is held.
The hybrid unit will now behave as a 4 wire to 2 wire converter with signal inputs at the mic/line Input connector and
telephone signal output at the output connector.
The call may be cleared by repressing the line connect switch or by means of the remote divert switch. The call can also be
cleared automatically by enabling either the K-break disconnect or the dial tone disconnect (using the optional HY-03DTD
dial tone disconnect plug-in PCB).
With both auto-answer and auto-clearance in use, call handling can be completely automatic in operation.
Making a Call
To initiate a call, lift the handset and dial the required telephone number. When the call has been established, press the
line connect switch and the call will be handed over to the telephone hybrid unit. To clear the line at the end of the call,
press the line connect switch. The line connect switch lamp is off in the non-connected mode and illuminated in the
connected mode.
