R.V.R. Elettronica VJ8000-TR, Technical Manual

Page: 54 / 81

Date: 25/07/03 R.V.R. Elettronica S.r.l. (BO) VJ8000-TR - R.F. Tube Amplifier
54
The calibration of the filament voltage and current cannot be executed with power supply,
because the measures must be executed in alternate voltage. To calibrate the filament
voltage is necessary to apply on CN7 sockets a voltage like as that of the tube (for example
with Yu148 is necessary a voltage of 7 V) and through trimmer P17 adjust the Test Point
output voltage for the value indicated on the table at TABLE D.
The filament current measure is obtained by a TA and then the voltage is included between
2.5Vac and 3.5Vac. For the calibration of the trimmer P16 proceed as follows:
1) Insert the tube in the socket and close again the RF cavity so that is possible to switch on
it.
2) Place an amperometric clamp so that to include one of the two power supply wires of the
filament that are connected to the socket.
3) Switch on the equipment and place the selector switch "MIN. FIL. ST.BY” to FULL FIL.
position.
4) Verify that led FIL 2 is lighted on.
5) Verify on the amperometric clamp the absorbed current is that of nominal working of the
tube.
6) Adjust P16 trimmer until to read on the test point a voltage value of 2,9 Vdc.
If it’s impossible to find quickly the voltage level, the protection could go in FAULT for
CHECK LIST ERROR; repeat the operation more times until to reach the correct value on
the Test Point output as indicated on the measure TABLE D.