Specifications

HY-03 User Handbook

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 tted 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

conguration 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 eective limiter, which will prevent high level

overloading problems. Ideally, the maximum input level should not exceed +12dBu. This

limiter is used for both line and mic input modes.

The output connection will deliver a balanced/oating 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 aects 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.

INTRODUCTION