R.V.R. Elettronica 4CX7500, Technical Manual

Page: 53 / 82

Date: 25/07/03 R.V.R. Elettronica S.r.l. (BO) VJ10000-TE - R.F. Tube Amplifier
53
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 4CX7500 is necessary a voltage of 7V) 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
TABLE D
.