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Model 606A
2-1
OUTPUT
TERMINATION
This
instrument
is calibrated
ONLY
when used
with a 50 ohm resistive load, such as the @ Model
606A-34A
Output
Termination,
into a high-im-
pedance (500 ohms or greater) input.
If the signal
is fed into a lower impedance
the output will no
longer be within calibration specifications and the
output of the Crystal Calibrator will be reduced,
particularly on the higher harmonics.
Any shielded rf cable of 50 ohms nominal impedance
with BNC male connectors is suitable for use with
the
Model
606A.
Single braid shield types are
suitable for use from maximum output to approxi-
mately -80 dbm
(30 microvolts).
Double braid or
solid shield types are recommended for use over
the entire attenuation range.
A good general pur-
pose cable consists of three feet of RG-55U (double
braid shield) with UG-88C/U
BNC
connectors
on
each end.
See also Figure 2-3 EXTERNAL OUT-
PUT
TERMINATION
for information concerning
output cable termination.
The output jack on the Output Termination has been
provided as
a BNC connector for maximum shield-
ing.
Clip-lead connection may be provided easily
by inserting
a UG-290/U connector with soldered-
on clip leads into the output jack ofthe Output Ter-
mination.
Keep
the
length
of the clip leads as
short as possible.
2-2
SETTING
THE
CURSOR
Set the cursor (movable index) with the CALIBRATE
knob so that it is aligned with the line under the
engraving reading FREQUENCY before setting the
frequency.
The FREQUENCY dial is calibrated only
after this operation is performed.
Sect. II Page 1
SECTION Il
OPERATING INSTRUCTIONS
2-3
OUTPUT
ATTENUATOR
The output attenuator contains resistors which can
be burned out by careless
usage.
If the output is
shorted out in the 3 VOLT
range or if voltage is
fed into the attenuator accidently, these resistors
may be burned out or heated up so that they are no
longer calibrated.
This may occur while measuring
the sensitivity of the receiver in a mobile trans-
mitter- receiver installation
when
the
transmit
button is pushed accidently.
An attenuator fuse is
available as an accessory when it is desired to use
this generator under conditions where the attenu-
ator may be burned out (see paragraph 1-6),
The
resistors
in the attenuator
are
NOT
field re-
placeable.
Do NOT
open the attenuator to check
these resistors as placement of the resistors
is
critical,
The attenuator may be removed from the
instrument
and returned separately to the factory
for repair.
2-4
USE
OF THE
3-VOLT
RANGE
The unusually high output range of 3 volts is useful
for driving rf bridges or other equipment requiring
a
calibrated
high-level
high-frequency
voltage.
This
useful
range
is obtained at the expense
of
operating the power amplifier stage near the over-
load
point.
You
will obtain
best life from these
tubes by not leaving the generator on the 3 VOLT
range
any
longer
than
necessary
to make
your
measurement.
Never leave it on this range during
warm-up or stand-by.
2-5
EXTERNAL
MODULATION
Take
care
when
using external modulation
vith
direct
coupling.
The dc level of the signal y ill
affect the average
rf level.
If only modulatioi
is
desired or if only the ac component of the molu-
lating signal has significance,
switch the MODU-
LATION SELECTOR to EXT. AC,
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