Nagra PORTABLE ANALOGUE AUDIO TAPE RECORDER Instruction Manual - page 28

SYNCHRONIZING A RECORDED TAPE. 

Check that the machine is fitted with the QSLI synchronizer circuit. This circuit is located at the right-

hand end of the battery compartment inside the machine. The circuit faces downwards, and has its 

front right corner cut away. 

Feed the pilot input connector (44) with the reference signal either from the pilot out socket on the 

ATN -3 (for synchronization to mains) or from the machine to which the 4.2 is to be synchronized. 

Turn the main function selector to the playback WITH loudspeaker position, and after a short period 

(typically 1.5 secs) the pilot indicator (15) should once again show a white segment. Check the level 

of the pilot signal from the tape by switching the modulometer switch (12) to the position "PILOT 

PLAYBACK" The needle should deflect about half way. If the modulometer selector is switched to 

the position "SYNCH" the meter will indicate the deviation between the external pilot reference and 

the pilot signal from the tape. 

FREQUENCY METER (OPTIONAL ACCESSORY QFM) 

This device measures the frequency of the pilot signal. If the meter switch is in the "Pilot Frequency" 

position, the meter will indicate the frequency. The scale is from +4% on the left hand side to  -4% 

on the right. The accuracy is about ±0.1% on the centre of the scale. In addition, the frequency 

meter circuit gives a warning if the frequency is more than 5% out from its nominal value. If this is 

the case then the rotary "Pilot" indicator turns black. The QFM exists in two version for 50 Hz and 

60 Hz (QFM 50 and QFM 60). 

QUARTZ CRYSTAL PILOT GENERATOR (OPTIONAL ACCESSORY QGX-3) 

This accessory is designed for synchronous filming without a cable between the camera and the 

Nagra. It supplies a signal whose frequency is 50 Hz ±0.001%, and is very stable within a wide 

temperature range. 

The output signal of the generator is connected to pin No 3 of the pilot socket. To record it, it must 

be re-introduced into the Nagra by bridging pin No 3 to pin No 4. This is done with the aid of a 

dummy plug, which is supplied with the generator, or by a standard plug with the two pins 

connected. The solution of using a dummy plug rather than a switch has been adopted in order to 

reduce the risk of human error. The QGX-3 is switchable and gives a 50 Hz or 60 Hz signal. 

PILOT INDICATOR 

This device is found on the upper right of the front panel. It shows a white cross when the Nagra is 

in operation and if a pilot signal of sufficient amplitude is provided, and if there is no "Alarm" signal 

in the pilot system. The "Alarm" signal will appear and turn the indicator black if the following 

conditions occur: 

A) 

if the frequency of the pilot signal is incorrect (on condition that the QFM 

frequency meter circuit is installed) 

B) 

if the pilot signal does not reach the pilot head (on condition that the QSLI 

synchronizer circuit is installed) 

This is indicated in the position "Test" of the main function selector. When the Nagra is in playback, 

this indicator will only show a white segment when a pilot signal is being played back from the tape 

and another pilot signal is being fed from outside. If one of these two signals is missing, the 

indicator will remain back. This is very important when using the QSLI.