R2
R1
C1
C2
G2
G1
CATHODE
HEATER
SUPPLY
RESERVOIR
HEATER
SUPPLY
(VARIABLE)
GRID 2 DELAYED
WITH RESPECT TO GRID 1
GRID 2 VOLTAGE
500 – 2000 V,
1
ms
0
NEGATIVE BIAS VOLTAGE
GRID 1 CURRENT
0.5 – 1.5 A,
2
ms
0.5
msMIN
GRID 1/GRID 2 DELAY
6890A
8. Under fault conditions most of the coulombs are often in
the power supply follow-on current, rather than the storage
capacitor discharge.
9. Measured with respect to cathode. Pre-pulsing of grid 1 is
recommended
for
modulator
and
high
rate
of
rise
applications. The last 0.25
ms of the top of the grid 1 pulse
must overlap the corresponding first 0.25
ms of the top of
the delayed grid 2 pulse.
10. DC negative bias voltages must not be applied to grid 1.
When grid 1 is pulse driven, the potential of grid 1 may
vary between
710 and +5 V with respect to cathode
potential during the period between the completion of
recovery and the commencement of the succeeding grid
pulse.
SCHEMATIC DIAGRAM
11. When DC priming is used on grid 1, a negative bias of 100
to 180 V must be applied to grid 2 to ensure anode voltage
hold-off. Also the higher grid 1 is pulsed, the larger the grid
2 negative bias must be to prevent the tube firing on the
grid 1 pulse.
12. Typical figures are obtained on test using conditions of
minimum grid drive. Improved performance can be
expected by increasing grid drive.
13. The time interval between the instant at which the rising
unloaded grid 2 pulse reaches 25% of its pulse amplitude
and the instant when anode conduction takes places.
14. The drift in delay time over a period from 10 seconds to
10 minutes after reaching full voltage.
#
E2V Technologies
CX1174, page 3
RECOMMENDED GRID, CATHODE AND RESERVOIR HEATER CONNECTIONS
R1
=
Grid 1 series resistor. 12 W vitreous enamelled wirewound is recommended, of a total impedance to match the grid 1
drive pulse circuit.
R2
=
Grid 2 series resistor. 12 W vitreous enamelled wirewound is recommended, of an impedance to match the grid 2 drive
pulse circuit.
C1,C2 7
reservoir protection capacitors with a voltage rating
5500 V;
C1 =
1000 pF low inductance (e.g. ceramic),
C2 =1 mF (e.g. polycarbonate or polypropylene).
Components R1,R2,C1 and C2 should be mounted as close to the tube as possible.