Table of Contents
Advertisement
Model 204B
3 - 1 .
INTRODUCTION 0
Section I11
Paragraphs 3-1 to 3-15
S E C T I O N 111
O P E R A T I O N
3-2. The Model 204B has four operating controls and
one output connector (see figure 3-1). A sine wave
signal in the 5-cps to 560-kc range
is
selected by
positioning the FREQ.
,
RANGE, and VERNIER con-
trols.
Output power level
is controlled
by
the
AMPLITUDE control which has a t least a 40-db range.
A 115/230 volt switch is on the rear panel when osci-
llators are equipped with an a c power supply o r re-
chargeable battery power supply,
3-4. Operating instructions for the Model 204B are
given in figure 3-1.
3 - 3 . PROCEDURE.
3 - 5 . GENERAL OPERATING
CONSIDERATIONS.
3-6. T o prevent damage to transistors i n the oscil-
lator,
a
blocking capacitor should be used in s e r i e s
with the output when connecting to a load a c r o s s which
there is
a
dc potential difference. When the capacitor
is used, initial current surge must be limited to
a
capacitance-voltage product less than 200 microfarad-
volts. F o r example,
if
a
20-volt potential difference
exists a c r o s s the load. use
a
10-uf capacitor (10uf x
20 v
=
200
! . l
fv).
CAUTION
DO
NOT CONNECT THE OSCILLATOR
ACROSS
LOADS
WHICH ARE REFERENCED
O F F GROUND
BY MORE THAN rt25
VOLTS; HIGHERVOLTAGES WILL BREAK
DOWN COMPONENT INSULATION,
3-7. When the Model 204B is initially turned on and
RANGE switch is s e t to X1, allow 20 seconds for os-
cillator to stabilize; only a few seconds
are
necessary
for stabilization when switching to other RANGE po-
sitions.If FREQ. dial is sweptat too
fast a
rate, out-
put voltage fluctuations will occur (since a wirewound
resistor is used
as
the variable frequency determining
element). If sweep speed is decreased
o r sweeping
is
stopped, oscillator output will stabilize
at its
normal
level.
3-8. To obtain maximum amplitude stability from
battery-powered
oscillators, wait 20 minutes after
turn-on to permit the battery voltage to stabilize. This
effect may cause
as
much
as a 1%
change in amplitude
during the first 20 minutes of operation.
3-9. When operating from batteries (Mercury
o r
Nickel-Cadmium) the batteries require replacement
o r
recharging (Nickel-Cadmium batteries only)
when
maximum oscillator output becomes less than 5.0 volts
rms open circuit o r less than 2.5 volts r m s into 600
ohms. For mercury battery replacement data, refer
to paragraph 3-26. Charging instructions for nickel-
cadmium batteries are given in paragraph 3-16.
3 - 1 0 .
OPERATION W I T H RECHARGEABLE
BATTERIES.
3-11. There is no change in the operating procedure
for an instrument in which the rechargeable battery
01369-4
supply has been installed. However, this power sup-
plypermits either a c operation for 115/230 vac &lo%
(selected by switch on r e a r ) 50 to 1000 cps power
sources o r battery operation for portable applications.
Battery operation only (with charger power cord dis-
cotnected) is required a t temperatures below 32'F
(0
$ ! )
and
is
recommended at temperatures above
104 F (4OOC).
3-12. When the RANGE switch is turned
OFF,
power
is removed from the oscillator portion of the instru-
ment and a resistor is connected a c r o s s the output of
the
power
supply. The charger will continue to
operate as long as the power cord is connected to a
power source. The resistor, placed a c r o s s the out-
put of the power supply, acts
as a
load in place of the
oscillator section to maintain a constant charge rate
through the batteries. A diode in the output circuit
prevents battery discharge when the oscillator is not
connected to a power source.
3-13. It
is
recommended that the power cordbe con-
nected to
a
power source whenever possible. This
w i l l prevent self-discharge of the battery cells and will
a s s u r e a fully charged battery whenever portable
operation is required. Turn the oscillator
OFF
when
not in use, particularly when operating with the power
cord disconnected.
3-14. When fully charged, the batteries will power
the oscillator for approximately 40 hours of contin-
uous o r intermittent operation provided they a r e at
a
temperature of 81 F + l o
.
If the batteries a r e oper-
ated
at
higher o r lower temperatures their capacity
is reduced
as
the temperature extremes
are approach-
ed; approximately28 h o p
at
122 F (500C)
o r approx-
imately 20 hours at -4 F (-20 C). At temperatures
beyond these extremes the batteries a r e not capable
of supplying their characteristic stable
discharge
voltage.
3-15.
The +122'F to -4'F temperature
range
is
adequate for most users, however, keep these limits
in mind when operating under field cotditions. Inter-
nal temperatures in excess of 122 F are
easily
obtained
if
the instrument is left in the sun, even with
a moderate ambient temperature. Good practice would
be to avoid storing, transporting,
o r operating in
direct sunlight other than for
a
very short period. Also
avoid placing the instrument in
a
location where
surrounding equipment might excessively
raise
the
internal temperature.
CAUTION
THE HERMETICALLY SEALED CELLS
IN
THESE BATTERIES MAY BE
PERMANENTLY
DAMAGED OR THEIR LIFE
DRASTICALLY
REDUCED I F EXPOSED TO EXTREMELY HIGH
TEMPERATURES. THIS DANGER INCREASES
UNDER PROLONGED CONDITIONS.
3-1
Advertisement
Table of Contents
