Nagra PORTABLE ANALOGUE AUDIO TAPE RECORDER Instruction Manual - page 27

5.0 PILOT 

INTRODUCTION 

The NAGRA 4.2 (NQ-L version) is equipped with a Neopilot system. This system developed by 

KSA, records a synchronization signal simultaneously with the audio, of 50 Hz (60 Hz in NTSC 

countries). Two signals are recorded in phase opposition so as to avoid any interference with the 

audio replay chain. The pilot signal serves as a speed reference to ensure that when the tape is 

replayed, it is always replayed at the same speed at which it was recorded. The pilot signal can 

either be supplied from an external source (a film camera for example) or can be generated by the 

internal crystal generator (QGX-3) if fitted. 

If a recording is made with a pilot version of the NAGRA 4.2 it is later possible, during playback, to 

lock the speed of the NAGRA by means of the pilot synchronizer (QSLI) to an external reference 

signal. This means that providing the "start" point of the recording is known for both the film camera 

and the NAGRA then the two can remain in perfect synchronization throughout the tape. 

To obtain a film with a synchronous sound it is necessary to keep the image and the sound 

continually slaved to one another. The acceptable tolerance is in the region of 40 msec. 

RECORDING A PILOT SIGNAL. 

A pilot signal can be recorded when recording either a line input signal or with microphones. 

RECORDING THE INTERNAL CRYSTAL 

For the 4.2 to record its internal crystal the QGX-3 crystal generator must be fitted to the machine. 

This is a circuit that is located on the left-hand end of the battery compartment inside the machine. 

There are two operating frequencies for this circuit 50 or 60 Hz. Check by means of the switches on 

the circuit that tha correct frequency has been selected. Once this is done then switch the main 

function selector to the "TEST" position. The pilot indicator (15) on the top right-hand side of the 

front panel should show a white segment. If this is not the case then check that the pilot crystal 

shorting plug is located in the pilot socket (44). 

This shorting plug is like a blank screw in jumper with the letters "XTAL" marked on it. If this is 

installed and the rotary indicator does not show a white segment then check that the machine is 

correctly powered and that the power selector (3) is in the correct position with respect to the 

supplied source. If this is all correct but the indicator remains black then consult your nearest 

NAGRA agent. 

Once the indicator shows a white segment then the recording is made in exactly the same way as 

described for recording the audio, the pilot signal will be recorded automatically. No further 

manipulation of the pilot system is needed. 

RECORDING AN EXTERNAL PILOT SIGNAL. 

Remove the crystal shorting plug in the connector (44) and feed the Pilot input socket (44) by 

means of the QCP cable. The other end of the cable must then be connected to the source (either 

an ATN-3, camera...). Check that the external pilot signal is present by switching the machine to the 

TEST position as above. While making a recording the cable must always be left connected. 

Make the recording as above.