Wavetek 3000 - OPTION -3 RF OUTPUT PROTECTION; Introduction to Option 3; Option 3 Specifications; Option 3 Operating Instructions

INTRODUCTION
Option

3 is a circuit breaker in the
RF outputsystem of
the instrument . This
prevents damage
to the RF outputsystem
in the event
that
largeRF
signals are
fed into the
signal generatorwhile
testing a transceiver .

In addition
to
the RF protection, the option
contains
a DC blockwhichwill prevent damage
to
the
Attenuator
if the RF
output is con-
nected to a circuit operating
at a DC
potential .
SPECIFICATIONS
Frequency
Range

1 to 520 MHz
Insertion
Loss*

< .2 dB
VSWR**

<
1 .15
Trip Time

<
2 msec
RF Trip Level

_ .7 W
Max RF

50
W
DC Blocking
Voltage

100
Volts
* This
loss is calibrated
out when module
is installed
in the
signal generator .
** The VSWR
of the
generator is
increased
to <1
.25 when this
module is
installed .
OPERATING INSTRUCTIONS
If an external
RF voltage of approximate-
ly
6 VRMS
or more is accidentally
ap-
plied to the instrument's
RF
output con-
nector, an internal switch in serieswith
the RF output will open . This
prevents
damage to the instrument's Attenuator
or
Output Amplifier .
Thisopen switch
will be indicated on the front panel by
the flashing of the UNLEVELED light .
Once the
switch is tripped, it will
latch
in the open position and remain
open
untilreset .

Also, a combination
of a high mismatch, high qutput level
(over .1 V) and changing frequency can
cause
the circuit breaker to trip .
After removing
the RF signal
causing
the overload,
the switch can be
reset
by momentarily
turning the front-panel
AC POWER switch
off .
THEORY
OF OPERATION
.
OPTION -3
RF OUTPUT
PROTECTION
NOTE :

Normaloperation
of,the UNLEVELED
light is a steady glow
if the instrument
is unleveled .

If the circuit
breaker
is tripped while the
instrument is un-
leveled, the UNLEVELED
light will vary
in intensityinstead
of flashing on and
off .
Figure
8/3-1
is a block diagram of the
RF circuit breaker . This block dia-
gram,
along with the M35-1 Schematic,
should be used to follow the informa-
tion contained in
this section .
With the instrument's
POWER switch
set
to the
OFF position, relay
Kl is in
it's normally
open position
. Thispre-
ventsany
damage to the
instrument while
it is not
in use . As soon
as AC power
is applied
to the instrument,
ICI will
compare the
voltage from

RF
monitor
CRI to a fixed
reference
voltage of ap-
proximately
5 V . As long
as the output
of the
monitor is less
than the 5
V
reference
voltage, the
output of ICI
will be
approximately+17 V .
This pos-
itive
output from
IM turns on the relay
driver,
Q1 . This
engerizesrelay K1,
thus
completing the
RF output circuit .
The positive output from
IC1 also turns
on Q2 .
This effectively grounds pin 7
of timer IC2,
which is being operated
as as astable
oscillator .

Withpin 7
grounded, the timer is
inoperative, and
its output,
pin 3, is high . The high out-
put from IC2
turns off Q3 . This prevents
any current flow to the
front-panel
UNLEVELED light .
If an external RF signal exceeding

6 VRMS
is applied to the instrument's RF out-
put connector, the
output from monitor
diode CR1 will go
above 5 V . This will
produce a negative
output from IM The
positive feedbackprovided
by R7 will
latch IC1 in this state
.

The negative
output from IC1
will turn off relay
driver Q1 . This
causes relay K1 to re-
turn to
its normallyopen position, re-
8/3-1