HP 460BR Owner's manual

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460BR
FAST PULSE AMPLIFIER
OPERATING AND SERVICING MANUAL

OPERATING AND SERVICING MANUAL
FOR
MODEL
46OBR
FAST PULSE AMPLIFIER
Serial
1720 and Above
5
r J
HE WLETT-PACURD COMPANY
275 PAGE MILL ROAD, PAL0 ALTO, CALIFORNIA, U. S. A.
46 OB 004-3

SPECIFICATIONS
Frequency Response
:
Gain:
Output Impedance:
Rated Output:
Maximum Output:
Input Impedance:
Noise Figure:
Delay Characteristics:
Rise Time:
Power Supply:
Size:
High Frequency
- closely matches Gaussian
curve when operating into
a 200-ohm resis-
tive load. 3 db point
is 120 mc.
Low Frequency
- off approx. 3 db at 100 kc
when operating into
a matched load. Off ap-
prox.
3 db at 3 kc when operating into an
open circuit
(i. e., CRT plates) or succeed-
ing amplifier.
With
@ 410B VTVM - when used with @
46A-95D Adapter, response +1 db, 200 kc
to
200 mc.
Approximately 15 db into
200 ohm load.
Approximately
200 ohms.
Linear Amplifier
- Approximately 8 volts
peak into
a 200 ohm load or 16 volts peak
into open circuit.
Pulse Amplifier
- Approximately 125 volts
negative peak open circuit (unilateral)pulse
operation 10%duty cycle.
200 ohms (t8volts input required for 125
volts output).
Less than
6 db.
Approximately
. 016 psec.
Approximately 0.003 psec.
No appreciable
overshoot.
19" relay rack panel, 5-1/4" high; 6-3/4"deep.
Weight:
12 lbs. Shipping weight 18 lbs.
Accessories Available: @<46A-l6APatch Cord:
200 ohms, 2' long.
@ 46A-16B Patch Cord: 200 ohms, 6' long.
@ 46A-95A Panel Jack: For 200 ohm cables
@ 46A-95B Cable Plug: For 200 ohm systems.
@ 812-52 Cable: 200 ohm cable in length to
specification.
($3 46A-95C 50-ohm Adapter: Type N to Op460,
50 ohm termination.
@ 46A-95D Adapter: @410B VTVM to @460,
no termination.
@ 46A-95E Connector Sleeve: Joins two 46A-
95B Cable Plugs.
@ 46A-95F Adapter: For connecting to 5XP
CRT.
($3 46A-95H Adapter: Type N to @460, 200-
ohm termination.
@ 46A-95J Adapter: Type N to ($460, no ter-
mination.
@ 46A-95K Adapter: @410 VTVM to ($5460,
200 ohm termination.
@ 460B-95A Adapter: For connecting to fp
Model 150A Oscilloscope plates.
low capacitance.

CONTENTS
Page
Section
I GENERAL DESCRIPTION
1-1 Description .............. 1
1-2 Accessories. ............. 1
Section I1 OPERATING INSTRUCTIONS
2-1 Inspection .............. 3
2-2 Installation .............. 3
2-3 Controls and Terminals ........ 3
2-4 Operation .............. 5
Section I11 THEORY OF OPERATION
3-1 Distributed Amplifier ......... 7
Section IV MAINTENANCE
............
4-1 Cover Removal 9
4-2 Tube Replacements .......... 9
4-3 Power Supply ............. 9
4-4 230 Volt Operation .......... 10
4-5 Trouble Shooting ........... 10
4-6
Connector ............. 10
4-7 Test Procedure ............ 12
Replacement of 200 ohm cable
Section
V TABLE OF REPLACEABLE PARTS
5-1 Table
of Replaceable Parts ....... 15

Figure 1. (A) Gaussian Response
(B) Typical 460BR Amplifier Response
Figure
2. (A) 0.01 psec Pulse Through @ 460BR Amplifier
(B) 0.02 psec Pulse Through 3 Amplifiers in Cascade

SECTION I
GENERAL DESCRIPTION
1-1 DESCRIPTION
The
@ Model 460B is a wide band distributed amplifier especially
designed to amplify high speed pulses to high voltage levels with
negligible overshoot. The output voltage
is sufficiently high to
drive the deflection plates of
a cathode ray-tube.
tain the fast rise time and shape of high speed pulses, it
is neces-
sary that the amplifier have
a wide, reasonably flat frequency re=
sponse.
approximates the gaussian response and hence retains the charac-
teristics of short fast pulses. Figure
1, Figure 2.
In order to re=
The frequency response of the
@ Model 460B closely
The high output of the 460B
is obtained with standard receiving
tubes by designing the amplifier primarily to amplify pulses
of a
single polarity.
to the maximum level of 125volts open circuit, while negative
pulses may be amplified to
a maximum level of 16 volts open cir-
cuit. A phase inversion occurs within the amplifier
so that a pos-
itive pulse applied to the input will be
a negative pulse at the out-
put. However, either upward or downward deflections of the CRT
is possible, since either the upper or lower deflection plate may
be connected to the ground terminal of the Model 46OB.
Thus the Model 460B amplifies positive pulses
1-2 ACCESSORIES AVAILABLE
A complete line
of accessories, for use with the Model 460B, is
available from the Hewlett-Packard Company,
are listed on the Specification page and
at the end of the Table of
Replaceable Parts, Section
V.
These accessories
1-3 230 VOLT OPERATION
This instrument
is normally supplied with the power transformer
connected for 115 volt operation, unless otherwise specified on the
order.
contained in Section
IV of this manual.
Complete conversion information for 230 volt operation
is
-1 -

SECTION I1
OPERATING INSTRUCTIONS
2-1 INSPECTION
This instrument has been thoroughly tested and inspected before
being shipped and is ready for use when received.
After the instrument is unpacked,
it should be carefully inspected
for damage received in transit.
follow the procedure outlined in the "Claim for Damage in Ship-
ment" page at the back of this instruction manual.
If any shipping damage
is found,
2-2 INSTALLATION
No special precautions are necessary except, when several
460
Amplifiers are to be used in cascade, they must have
a good com-
mon ground,
i. e. : mounted in a relay rack, and the high-voltage
output must be kept away from the input to avoid the possibility of
feedback.
2-3 CONTROLS AND TERMINALS
ON This toggle switch controls the a-c power supplied to the instru-
ment from the power line.
LINEAR, PULSE
This rotary switch selects the type of amplification desired.
FUSE
The fuseholder, located on the panel, contains the power
line fuse.
fied in the Table of Replaceable Parts, Section
V.
Replacement fuses should be of the type speci-
POWER CABLE
The three-conductor power cable supplied with this instrument
is terminated in
a polarized three-prong male connector. The
third contact
is an offset, round pin added to a standard two-
blade connector which grounds the instrument chassis when used
-3 -

h
k
rr
3
0
0
z
w
0
I-
3
I-
3
0
cn
0
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Y
W
a
v
a
5
a
a
460 B
LINEAR
PEAK VOLTS INPUT
460 B 4608
LINEAR PULSE
Figure 3.
Linearity Characteristics of 460BR Amplifier
.25 V
2 .H .25V
460 A
_I
460 B
PULSE
460A
1 -
.25V 2.5V
460 8
LINEAR
460
A
i
Figure 4. Cascading 460 Amplifiers
460 B
PULSE

with an appropriate receptacle.
to connect this plug to
a standard two contact system.
the adapter
is used, the ground connection is brought out on
a short wire. This ground lead should then be connected to
a suitable ground for the protection of operating personnel.
An adapter may be used
When
INPUT AND OUTPUT
The input and output jacks on the control panel, require special
200-ohm connectors and cables. (See paragraph
1-2).
2 -4 OPERATION
Connect the Model 460B to the power line, turn on the power
switch and the instrument
is in operation.
To use
as a linear amplifier to amplify sine waves, etc. , or
pulses of either polarity, set the LINEAR-PULSE switch to the
LINEAR position.
position the output
is limited to 16 volts peak into an open circuit
or
8 volts peak into a 200-ohm load.
a phase reversal between input and output is present and that a
positive input pulse appears in the output as a negative pulse.
When the LINEAR-PULSE switch
is in this
It must be remembered that
To realize the full output capabilities of the Model 46OB, the
LINEAR-PULSE switch must be in the PULSE position and
a posi-
tive pulse of about
8 volts peak be supplied to the input.
In the PULSE position of the LINEAR-PULSE switch the amplifier
tubes are operated at higher than normal supply voltages.
grid bias
is increased to keep tube dissipation within ratings.
Under these
conditions (1-8 volt input) the rated tube dissipation is
reached with a duty cycle of 10%. Lower driving voltages will
allow proportionally higher duty cycles, but the output voltage
will be lower.
The
See Figure
3.
In order to supply this 8-volt positive pulse to a Model 460B, the
units may be cascaded or used with one or more Model 46OA
Wide Band Amplifiers, see Figure 4.
In general, when cascading
460 amplifiers, consideration must be given to the polarity
as
well as the amplitude of the pulse to be amplified. For maximum
deflection, the set-up must be arranged so that the input to the
last 460BR amplifier is positive and of approximately 8 volts peak
amplitude. This
is easily done because the 460BR inverts the in-
put pulse. Hence, an additional 460B can be used when necessary
to invert pulse polarity. In most applications an input of about 4
volts
is sufficient to give satisfactory deflection of a cathode-ray
tube. Certain precautions must be taken when cascading several
460 Amplifiers, see Paragraph 2-2, INSTALLATION.
-5-

SECTION 111
THEORY OF OPERATION
3-1 DISTRIBUTED AMPLIFIER
The extremely rapid rise time of the
460B is obtained through the
use of the distributed amplifier;* the operation of which is explained
as followsa See Figure 5.
In the distributed amplifier, the tubes are connected at fixed inter-
vals between two artificial transmission lines that have equal pro-
pagation velocities. A signal applied to the input terminals passes
down the grid line and appears on each grid in turn. The resulting
plate signal currents flow in the plate line, half in one direction
and half in the other.
tube to the output are the same length in terms
of line sections
traversed, the individual plate signal currents
will arrive at the
output termination in phase, thus adding together in the load. The
plate signal currents flowing in the reverse direction are absorbed
without reflection in the reverse plate line termination.
put voltage of
a distributed amplifier is given by the relation
Eo -
plate signal current, and Zp is the plate line impedance.
Since the paths from the input through any
The
out-
- nZp
-ripwhere n
is the number of tubes in the stage, ip is the
The number of tubes that can be used in
a single stage is limited
by grid loading which occurs
at high frequencies because of the
increased input conductance of the amplifier tubes. This effect
reduces the high frequency gain and in effect restricts the fre-
quency range of the amplifier.
When amplifiers are cascaded, the rise time
will be greater than
that of
a single unit in accordance with the relation:
T=
112
where:
T is total rise time
t
is the rise time of a single
n
is the number of 460 units.
unit
(2mbXlO-9 sec.)
In addition to the rise time of the amplifiers, the rise time of the
RC combination formed by the capacitance of the deflection gates
* Ginzton, Hewlett, et all, Distributed Amplification, Proc.
IRE, Vola 36, August, 1948

and the internal resistance of the 460B (200 ohms) shouldbe
considered.
In any case, the total rise time of any number of 460 Amplifiers
in conjunction with any load may be found approximately by the
following relation:
where: n
= number of 460 Amplifiers
t rise time of one 460 =
2.6XlO-9 sec.
C
T total rise time.
total shunt capacitance on the
output of the
460 in farads.
-8-

SECTION IV
MAINTENANCE
4-1
4-2
4-3
COVER REMOVAL
You will be able to slide the one-piece cover off the instrument
after removing the four screws in the rear of the cover.
TUBE REPLACEMENTS
In many cases instrument malfunction can be corrected by replac-
ing
a weak or defective tube.
ment or component replacement, check the tubes. Adjustments
made in an attempt to compensate for
a defective tube will often
complicate the repair problem.
Before making any internal adjust-
It
is good practice to check tubes by substitution rather than by
the use of
a "tube checkert1. The results obtained from the "tube
checker" can be misleading. Mark original tubes to insure re-
turn to the same socket.
defective Replace only tubes proved to be weak or
Any tube with corresponding standard EEIA (JEDEC) characteristics
can be used
as a replacement.
POWER SUPPLY
The 460B power supply delivers two output voltages depending
upon the setting of PULSE-LINEAR switch S1.
With S1 in the PULSE position, selenium rectifiers CR-1 and CR-2
are connected in
a voltage doubler circuit. The dc output voltage
between ground and the common junction of capacitor C22, filter
choke L28, and fuse
F2 with the line voltage set to 115 volts will
be
270 & 15 volts.
ing instrument performance.
Ripple voltage can be quite high without affect-
When switch S1
is in the LINEAR position, rectifiers CR-1 and
CR-2 are connected in parallel as half-wave rectifiers. The dc
output voltage between ground and the point described above
will
be 110 volts when the line voltage is set to 115 volts. Ripple volt-
age
is again not critical.
Low power supply voltages are generally caused by weak selenium
rectifiers, leaky filter capacitors, shorted tubes or off-value re-
s is tor s .
-9-

4-4 230 VOLT OPERATION
The @ Model 460B can be quickly and easily converted to operate
from
a nominal 230 volt 50/1000 cps power source.
ment is normally supplied with the dual primary windings of the
power transformer connected in parallel for 115 volt operation.
To convert for 230 volt operation, reconnect the primary windings
in series as shown on the schematic diagram. The line fuse
F1
must also be changed from 0.8 amp slow-blow to 0.4 amp slow-
blow,
The instru-
4-5 TROUBLE SHOOTING
Low gain, low output, and impaired frequency response are
all
directly related to tube mutual conductance and power supply out-
put voltage. Consequently, should any of the above symptoms ap-
pear, the power supply output voltages should be checked (para.
4-3) and the tubes should be checked (para.
4-2).
Impaired frequency response, low gain, and/or excessive hum
can also be caused by open or shorted coils and by defective ter-
minating resistors or screen resistor
s.
If Bt fuse F2 blows, look for
a Bt short, loss of bias, or
a shorted
5654 tube,
If a 5654 tube was responsible for the blown fuse, check
the appropriate screen resistor and resistor R1 for possible damage.
Resistor R1
is made up of five 980 ohms resistors connected in
parallel. Any one of these resistors could open without greatly
affecting the operating voltage
s ,
The cans of electrolytic capacitors C22, C23, and C24 are insu-
lated from the chassis.
chassis the bias voltage
will also be shorted.
normally not more than about
10 volts and is not dangerous to per-
sonnel, but tube damage
cm result if this voltage is removed,
If these capacitors are shorted to the
The bias voltage
is
4-6 REPLACEMENT OF 200 OHM CABLE CONNECTOR
1,
Cut 200 ohm cable to length desired,
a point where shielding and outer insulation are even with
the end of
a center canductor support bead.
cable length to tip of banana plug
will be approximately 1/4"
shorter than trimmed cable length.
Trim end of cable to
After assembly,
-10-

REAR RETAINER CAP "0" RING (432-40) CONICAL WASHER (46A-76K)
REAR PLUG BODY BANANA PLUG
(125-33
1
CTIONS) L d J
t
OUTER INSULATION CENTER CONDUCTOR FRONT PLUG ASSEWBLY
(46A
- 76C)
Fig. 6 Exploded View of the 46A-95B Assembly
2.
Remove outer cable insulation for a distance of 2" from
cable end.
3, Remove three support beads from center conductor. To
do this, upset shielding just enough to release beads.
4. Slide the following parts over the cable shielding in order
given: rear retainer cap, large washer(s), rubber
l'O1r
ring. Either one or two washers are included with the
connector parts
at the factory.
134 washers supplied. Purpose of additional washer
is
given in step9 .
Use all of the large 512=
5. Slide rear plug body over shielding. Hold rear plug body
against end of outer insulation and cut off shielding 3/16"
from beveled end of rear plug body.
6. Fan shielding out and bend back over rear plug body.
Trim off any shield wire protruding beyond beveled edge.
7. Place conical washer over shielding with flat side toward
end of plug.
8. Insert center conductor through hole in center of front
plug assembly, slide assembly back over conical washer.
Thread rear retainer cap on front plug assembly.
must be firmly tightened
so that it cannot be rotated on
Plug
41-

end of cable, The use of strapwrenches
is recommended,
9. Measure distance between front edge of rear retainer cap
and front edge of front plug assembly,
not be less than 31/32",
in step d will increase this distance,
This distance must
Additional washers installed
as
10, Wrap and solder the center conductor to the base of the
banana plug.
Do not pull center conductor excessively
tight when connecting to banana plug,
11, Resistance between outer connectors must be less than one
ohm,
than one ohm,
center connectors must be greater
than 500 megohms.
Resistance between center connectors must be less
Resistance between outer connectors and
4-7 TEST PROCEDURE
Testing of the 46OB is
a long tedious procedure, and is not often
needed. However, anyone with the necessary equipment for mak-
ing the several somewhat complex test set-ups can complete the
procedure.
will be required.
The following
@ instruments or their equivalent
Signal Sources
, . , Models 212A, 608C, and 65OA.
Voltmeters
. . . . . Models 410B and 400D/H/L,
Oscilloscope
, . . . , . . . . , , Model 15OA.
Attenuators
. . . . . . Models 355Aand 355B.
Miscellaneous
. . . . . , . . Cable Adapters
The complete Test Procedure
is available from the @ Factory as
a Service Note.
Service Notes
is your local @ Representative who will be pleased
to supply you with copies on request.
Perhaps your most convenient source for these
Your local
@ Representatiye' also maintains complete facilities and
specially trained personnel to assist you with any engineering, ap-
plication, test, or repair problems you may have with
@ Instruments.
-12-

Figure 7.
Top View of @Model 460B Fast Pulse Amplifier
Figure
8, Bottom View of @ Model 460B Fast Pulse Amplifier
- 13-

f" Q'
0
- 14-

SECTION V
TABLE OF REPLACEABLE PARTS
NOTE
Any changes in the Table of Replaceable Parts will be
listed on a Production Change sheet at the front of this
manual.
When ordering parts from the factory always include
the following information:
Instrument model number
Serial number
-hp- stock number of part
Description of part