Nagra PORTABLE ANALOGUE AUDIO TAPE RECORDER Instruction Manual - page 12

PILOT PLAYBACK 

This indicates the level of the pilot signal played back from the tape. 

PILOT FREQ  

This indicates on the +4 to  -4% scale of the modulometer, the frequency 

deviation as determined by the QFM frequency meter circuit (if fitted), 

between the pilot signal being recorded or played back and the 50/60 Hz 

reference. 

LEVEL  

The modulometer will indicate the level of the direct or the recorded signal 

on the decibel scale. 

BATT. RESERVE 

Indicates on the lower scale, the bold line shows the supply voltage reserve; 

the lower limit at the extreme left of the bold line represents 11 V. 

VOLT/CELL 

  This is a battery check indicating on the V/CELL scale of the meter and 

indicates the Volts per cell of the batteries. 

COMPRESSION 

Compression reading in decibels on the ALC compression scale when 

switch (10) is in the AUTOMATIC position. 

MOT 

This indicates the motor current. Maximum deviation = 250 mA. 

BIAS 

This indicates the record bias level on the V/CELL scale. 

NOTE : The QRT / QRR radio transmitter and receiver accessories are no longer manufactured. 

13. FILTER SWITCH 

This is a six position rotary switch, allowing different filter possibilities to be switched in or out. 

LFA 2 

Low frequency attenuation, -8 dB at 50 Hz. 

LFA 1 

Low frequency attenuation, -4 dB at 50 Hz. 

FLAT 

The machine has a linear response. 

HP 1 

High pass filter, -10 dB at 50 Hz. 

HP1+LFA1 

Combination of high pass and low frequency attenuation, -14 dB at 50 Hz 

and -3 dB at 400 Hz. 

HP2 

High pass filter, -20 dB at 50 Hz.