32. When the AC power has been turned on as deseribed above, all units 
except these in stand-by and the motors on the PL sound level recorders 
should be operating. The PL recorder motors will be actuated by the auto 
matic switching unit unless their motor control has been switched to MANUAI 
and their amplifier control switch is off, 
33. A 15-minute warm-up period should be allowed for the amplifier channel 
and the automatic switehing unit to become stable. During this period the 
sensitivity of the automatic switching unit will change considerably and it 
will not operate properly. 
Sh, Rack 1: Set the CHANNEL NO. 1 VOLUMES or CHANNEL NO. 2 VOLUME, according 
to which channel is being Wee a “approximately 10 and the BUS VOLUME at 
approximately 6 db, These settings will vary depending upon background noise 
conditions, To Se the line amplifier from being overloaded, the channel 
volume control, which follows the preamplifier and governs the iApat to the 
following line amplifier, should be set somewhat higher than 10 when high 
background noise prevails, The RUS Oli control governs the voltage 
applied to the system bus OATES the minimum writing level of the PL 
sound level recorder; it should be set lower thun 6 db when high background 
noise prevails to prevent the PL semper from writing too high on the paper, 
thereby reducing the writing range available, 
35. Turn the TO RECORDER switch 5.101 on the left side of the front panel 
of the Time Tone Amplifier (Rack a: shelf three from the top) to the BUS 
position. In BUS position, +10), connects the "High-speed" PL recorder to 
the system bus and throws the "High-spesd" indexing relay under chronometer 
‘control, Turn the WEOPHONE S102 switch (to the right of the TO RECORDER 
switch) to whichever of Ene! ive magnetic tape recorders is in use, Recorder 
#1 is in Rack 3g Recorder #2 is in Rack 2. Turn the third switch on this 
panel (to the right of the "Mirrophone™ switch) to the BUS. position. This is 
switch S-103, marked joyroR. Plug 600-ohm Permoflux earphones into the 
monitor jack at the Tigut of the time tone amplifier panel, The volume . 
control labeled MONITOR R-i22 for these earphones is just to the left of the 
earphone jack. The station opsrator should listen to the signal on-the bus 
through these earphones, 
- 36. On the bottom panel of rack one there is a volume control for the 
‘monitor speaker which reproduces the signal on the bus which is pene fed 
to the recorders, 
37. Rack 2: Turn the VOLUME control of the automatic switching unit at 
the left of the top panel to the fuli *on" position. Turn-.the SENSITIVITY 
control at the right of the top panel clockwise to the point where the 
background noise just fails to fire the automatic switching unit, This 
adjustment may require attention off and on throughout the day, and some 
false alarms may be caused by sudden changes in background noise. When 
the automatic switching unit fires it places the PL graphic level recorders 
in operation, After a false alarm has occurred the automatic switching unit 
must be reset manualiy by operating the reset switch located just to the left 
Ei 
