connected to the input of the Amplifier M in place of the track announce signal. The
Amplifier M has three outputs. With the oscillator level control set to zero the
outputs are as follows:
Output No. 1 is at a level of –35dBV which, when the oscillator key is in the
“on” position, is connected to the oscillator position on the input selectors on the
Microphone Cassettes, this being the level required for standard level in a
microphone channel. In other positions of the oscillator key this output line is
connected the 0 V rail.
Output No. 2 is at a level of –10dBV and, in addition to feeding the track
announce inputs on the Main Cassettes, also supplies level for checking the V.U.
Meters through the oscillator positions of the meter selector switches.
Output No. 3 is a zero level output which is available on both channels of
Sk4, a 5-pin Tuchel socket. It is a low impedance output, which must not be loaded
with less than 2k
Ω
.
8.8.4 Tape Machine Test
For sending tone to tape machines the oscillator key is set to the up position
marked “To Tracks”. The oscillator is fed to the track announce line as in the “on”
position but in addition RL5 is energised to operate the change-overs in the
Amplifiers N to accept the oscillator from the track announce line. In addition, RL1
is operated to quiet the control room monitor loudspeakers.
8.9
Metering
As in the Control Room Monitor Cassette a 3-position, centre “off”, switch is
provided. This enables the levels either at the two studio playback line outputs or at
the alternative talkback and intercom line outputs to be observed on the V.U. meters
associated with the left hand Main Cassette when the meter switch in that cassette
is suitably set.
There is no meter socket on the cassette but the +20V and –20V are
available on SK6 for test purposes.
A spare socket SK5 is also provided.
8.10
Power Supply
The cassette employs the standard power unit. It consumes about 49mA at
+20V and 91mA at –20V.
9.
FRAME
9.1
Capacity
Two frames are available one of which will accommodate up to 12 cassettes
and the other will accommodate up to 24 cassettes. A smaller number can always
be used.
Blank panels are available to fill vacant spaces. These have plugs on which
the sockets of the cableforms can be parked.
