RCA BN-6B User manual

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BROADCAST
AUDIO
EQUIPMENT
RADIO
CORPORATION
OF
AMERICA,
Industrial
Electronic
Products
-
Type
BN-68
l
ransistor
Portable
Remote
Amplifier
18
-2
47:•J-3
Tm• Ii i

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EQUIP MENT LOST OR DAMAGED IN TRAN SIT
\Xlhen delivering 1he equipment 10 yo u. the truck driver or carrier's agent will present a receipt for your si gnature .
Do not s ign it until yo u huve I a) in s pected the comainers for visible signs of damage and (h ) counted the containers and
compared wi th the amount s hown on the sh ipping papers. If a shortage or if evidence of damage is noted, insist that
notation 10 chat effect be made on th e s hipping papers befor e yo u sign them.
Further, after receivini; the equipment, unpack it am! in spec t thoroughl y for concealed danrnge. If concealed damage i,
ti scovered, immediately notify rhe carrier, co nfirming chc nmification in wr i ting. and sec ure an inspection report . This
item should be unpacked and in spec ted for damage W I THIN 15 DAY S afcer rece ip t.
Repo rt all s hortages and damage s 10 RCA. Broudcast and Te levision Department. Camden 2, N. J.
Radio Corporation of America will tile all claims for lo ss and damage on thi s equipment so long as the inspection report
is
obtained. Dispo sition of 1he damaged item will be furni s hed by RCA.
REPLACEMENT PARTS AND ENGIN EERING SERVI CE
RCA field eng ineer ing service is avai lable at current races. Reque sts fot field engineering s ervice ma)' be addre ssed 10 yo ur
RCA Broad cast Field Represenliltive or the RCA Service Company , I nc .. Broadca st Service Divis ion , Camden, N. J. Tclc1,hone:
WOod l awn 3-8000.
\X/ h en order i ng reph1ceme111 parts, please i;ive sy mbol , description, and swc k number of each item o rdered .
The par! whic h will be supp lied ai;ains1 an order for a replacement item ma> • not be an extt cr dup licate of the original part .
However, it will be a satisfactory rep l acement differ ing only in minor mechanical or elenricnl characteristics. Such
differences will
in no way impair t he ope r ation of the equipment.
The following 1abulu1ions I.isl service p11rL~ and electron tube ordering ins1ruc1 ions acco rding 10 your geographical loca 1i on.
SERVICE PARTS
LOC ATIO N OR
DER SE RV ICE PA RTS FROM:
Continental United States, including Alaska
and Hawaii
RCA Electron Tube Divi s ion , Pare s and Equ i pmenr. P. O. 8(lx 654, Cam-
den, New Jersey or through your nearest RCA Regional Oflice, Erner•
gency orders may be te l ep hon ed, t elegraphed or 1eleryped t0 RCA
Emergency Service, Bl
dg. 60, Camden, N.J. ( Telephone: WO 3-8000 ).
Dominion of Canada
RCA Victor Com p any L imited, 1001 Lenoir Street, M onireal, Quebec
or 1hrough your lo c al Sales Representative or his office.
Outsi,de
of Comi n enra J United Scates, Alaska,
Hawaji and rhe Dominion of Canada
RCA I nternational Div i sion, Cl ark, N. J., U.S.A., or throu , i:;h y our l oc al
Sales Rep resentative.
ELECTRON TUBES
LOCATION
ORDER ELE C TRON TUBES FROM :
Con1·nen1:il United Sta tes,
including Al aska
Local RCA T u be Distribu t or.
and
H awaii
Dominion of
Canada
RCA Victor Compan) ' Li mited,
1001 Lenoir Street, Montreal.
or th r oug h you.r local Sales Representat i ve
or his oflice.
Qucber
Oucside of Continental Un i ted States, Alaska, Local
RCA Tube
Distributor or from:
Tube
Depanmenr
Hawaii and t he
D ominion of Canada
RCA In t ernational Division
. ,o Rockefeller Plaza
New York 20.
New York, U.S.A.
RETURN OF EL ECTRON TUBES
H for any rea so n, it is desired co return tubes, please return them through )' Out local RCA tube d: stributor, RCA Victor Co ..
Ltd.,
or RCA I nternational Div., depending on your location.
PLEASE
DO NOT RETURN TU B ES D IR ECT LY TO RCA WI THOUT AUT H OR I ZATION AND SH I PP I NG
I NST R UCTIONS.
It is importont tha t complete information regarding each tube ( including rypc, serial number. hour s or se rvice and rc:ison
for i1 s rcrurn ) be given.
\Vhcn ruhes nre returned. they s hould be shi1>ped 10 the addre ss specified on the Return .Au t horization form. A copy nf the
.Return Authorization and also a Service R eport for each cube shou ld be packed wi th the tube s.
A1la11/11 J. Georgia
1121 Rhode s- H averty Bl dg.
I34 Peac htree Si. N.W .
JAckson 4-7703
Dall,, s 35, Te.-ras
79 01 Empire Fr eewa) '
FLee1wood 2-391 I
D- BTE·J
LIST OF RCA REGIONAL OFFICES
Bo s /011 J 6, Mass.
Chic11go 5-1, 111 .
Room 2.i0I, J ohn H ancock
200 Berkley St.
H
Ubbard 2-1700
Bldg. 1186 Merchandise Mart Plaza
DEiaware 7-0700
Ho/l yu • ood 28. Ca lif.
RCA Bldg., 1560 N. Vine St.
HOil y wood 9-21 54
IJ1 ·1111ch-S u11 Fruucisco 2, Calif.
420 Taylor St.
ORdway 3-8027
Kama s City 6, J\li .sso11ri
. HO Home Savings Bldg .
HA rrison 1-6 480
Se,,ttle. 11'1 ashi11gJ011
2250 First Ave .. S.
MAin 2-8350
Cle 1•ela,1d 15. Obfo
1600 Keith Bl dg .
CH
erry 1-.~450
' ew }' ork 20, ' e11 • \' ork
-'6 W. 49 th St.
JUd son 6-3800

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BROADCAST AUDIO EQUIPMENT
INSTRUCTIONS
Type BN-6B
Transistor Portable Remote Amplifier
Ml-11221-B
RADIO CORPORATION OF AMERICA
INDUSTRIAL ELECTRONIC PRODUCTS , CAMDEN , N . J. ·
PRI N TED IN U.S.A.
DU 5109
,.
!

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2
Figure I - Type BH- 68 Transistor Portable Remote Amplifier
TECHNICAL DATA
Power Requi red
AC Power : 117 v,
50- 60 cyc l es , 5 wa tt
DC Supply: Batter i es Ml-11778 (not sup-
pl ied with Ml-11221-8)
Fuse
1
/1 6 amp 3AG
Transistor and Diode Comp lement
5 2N
175
3 2N 109
1 2N35
or
2 N2111
(RC A) Inp ut stages and succeed-
ing ga in stage
(RC A) Gai n stage , driver and
PNP part of the complementary
symmetry
output stage
{Sylvania) NPN part of the com-
plementary symmet ry output
s ta ge
2 1N91 Ge rmanium rectifiers
Frequency Response
±1-1/2 db at JO to 15 ,000 cps
Source Impedance
150 ohms
Load Impedance
30
ohms
Input
150/30 oh ms
Output
600/150
ohm+ 18 dbm
Gain
88
db± 2 db 150-ohm source to 600-ohm
load
Harmonic Distortion
Less th an
Less
than
Less than
Less than
Less
than
Less
than
N oise Level
-52 dbm
1. 51 at 30 t o 50 cps
a at
50 to 10 ,000 cps
3 .% at 10 ,000 to lf ,000
(+ 18
db out put
cps
1. 251
at JO to 50 cps
a at
50
to 10,000 cps
1. 251
at 10 ,000 to 15 ,000
(+ 8
db outp u"t)
cps
Sin9le channel , gain 68 db, master
gain control set at 12 , mixer
gain at 16 .
correspond
to signa l -to- noise
· ratio 70 db at rated power output
of+ 18 dbm .
Dimensions and Weight
Height - 5-
5/8 inches
Width - 16 -1 /2 inches
Depth - 10-1/2 inches
wei9ht - 25 po unds (approximat ely)
Finish -two tone umber gray

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---
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3
DESCR
IP
TIO
N
The
Type
BN-68
Amplifier,
MI
-
1122
1-
B,
is
a
four
channel
unit
designed
especially
for
broadcast
programs
remote
fr
om
the
studio.
This
unit
amplifies
low
level
signals
to
a
level
suitable
for
transmission
over a
tele-
phone
line
to
the
studio.
Other
features
in-
clude
complete
cuing
and
monitoring
facili-
ties,
etched
circuit
boards, use
of
tr
ansis-
tors
and
ge r
ma
nium
diodes
and
of
either
batte
r
ies
or
self
-
contained
ac
power supply.
Th
e
BN-
68
amplifie
r
is
supplied
in
a
rugged
carrying
case
.
The
specially
designed
lid
may
be removed
from
the
hinge
pins,
tu
rned
over
and r
eplaced
against
the
side
with
the
mou
n
ting
grommets. In
this
position
the
lid
forms a
rest
for
the
entire
assembly
at
an
angle
which makes
the
control
panel
easily
accessible
for
operation
.
The
AC
power cord
is
supplied
clamped
inside
the
lid
of
the
carrying
case
. A w
eather-proof
canvas
carrying
case
MI-11377
is
also
available
as
optional
or
accessory equipment.
Circuit
Th
e
BN-68
Amplifier
has
four
separate
in-
put
channels
which
can
be
operated
eithe
r
6
CD
3
0
z
0
"'
Cl) ,
z - 3
0
CL
Cl)
IA.I
- 6
er
balanced
or
unbalanced. Balanced
operation
is
accomplished
by
plug-in
t
ransfor
mers
MI
-
11776
(992074-1) which
may
be o
rder
ed
sepa
rately.
The
2Nl75
low-noise
transisto
rs are used
in
the
input
stages
and
in
the
follo
w
ing
pr
e-
amplifier
stage.
nie
drive
r
stage
is
a con-
ventional
amplifier
stage
.
No
phase
inversion
is
necessary
since
a
comp
lementary symmetry
stage
is
used
in
the
output
.
An
isolation
pad
is
connected
to
the
transfo
rmer
prima
ry
to
protect
the
output
transistors
from
damage
in
case
of
shorting
the
line
.
The
VU
meter
both
monitor
s,
the
output
level
and
tests
the
battery
curre
nt.
A
sep
ar-
ate
flashlight
type
battery
is
n
ecessa
ry
for
vu
meter
illumination
wh
en
th
e
unit
is
opera-
ted
from
battery
supply
.
Batteri
es
are
not
supp
l
ied
w
ith
the
equipment
.
Lightweight
,
long
life
mercury
batteries
should
be
ordered
for
the
batte
ry
power
supply,
Th
e
battery
kit
MI-11778
may
be
ordered
which
includes
5
PR.
Mallory
lfl'Rl35R, 6. 5
volt
type
and one
RCA
IIVS036,
1.5
volt
type.
Th
e ac p
owe
r
supply
consists
of
a f
ull
wave
re
ctifie
r
circuit
u
sing
germanium
diodes
and an
r-
c
filter.
"""
30
~o
1
00
200
300
~00
1000
300
200
0
FREQUENCY IN C
YCLES
PER
SECOND
0
~000
10000 I
~0
00
.4
·
8946054
-0
Figure 2 - Typical Frequency Response Curve
\

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4
T RANSISTOR M IX ERS
PRE AM PS
r - - - -
I
MIC 1 ~lllo----0---0' ~S2
A TI
MI C2 ~11
AT 2
M
IC3~ 11
An
M
IC 4 o--1
ATd
------,
I
TRA NS ISTOR
AMPLIFIER ISOLATION
PAO
C
UE
MIC I
SWHCH
l l N(
MONITOR
OUTPUT
TRANSFORMER
vu
PAO
Figure 3 - Block Diagram
IN S TALLATION
Transistors
All transistors are shipped in place. The
sockets are mounted on the printed circuit
boards. Replacement transistors are easily
plugged in as needed.
CA[f['JON: Do not remove or inser t the
transistors when the po w er is ON.
Transi s tors nuy be dam ged resul t in g
in excessive noise an d d istor t ion .
Allow approxi m ately 1 minute after
power is o ff b efore removing tran-
sistors.
Internal Connections
The BN-6B amplifier is shipped connected
for either 150 or 30 ohm unbalanced input and
a 600 ohm output. A plug is provided for each
input socket. For an unbalanced line either
30 or 150 ohm microphone may be used. FOr a
balanced line the plug-in transformer MI-
11776 may be ordered . The sockets are con-
nected
for 150-ohm input balanced line; how-
eve r, for a 30-ohm balanced line, move
connections on the socket from terminal 1 to
terminal 2 and from terminal 5 to terminal 4,
Installation of Batteries
The preamplifier is shipped wi thout
batteries. These may be ordered separately
as Ml-11778 which includes five PR. Mallory
11TR 1 35R - 6.5 volts and one RCA #\1S036 - 1.5
volts. To install the RCA battery, remove the
cover and place it firmly in the clips se-
cured to the top shelf of the chassis in the
right hand corner. A cylindrical case holds
the five batteries and is secured by two
clips fastened to the bottom of the chassis.
VU t-eter
The VU meter mounted on the front panel is
a standard meter and provides a means of
measuring both the volume level of the ampli-
fier output and the battery current. To mea-
sure the battery current, turn the POWER
switch to the BATT TEST position. Wh en the
meter indicates the center position or 100,

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the battery current is at its peak, 32 volts.
The amplifier should not be operated with the
battery reading below 1 0% less than the 100
reading. The VU meter attenuator is designed
to give a meter reading of O on the VU scale
with an output of 8 dbm. The mercury type
batteries are capable of appr oximately 40
hours
continuous operation . The RCA battery
which supplies the meter illumination should
be changed whenever
the light appears dim.
AC P owe r Co rd
The eight - foot power cord is supplied
folded and clipped into the lid of the carry -
ing case as sho wn in f i gure 7. The AC con-
nector on the back panel is a t w ist lock
type. Co n nect the 'power cord matching plug to
the amplifier connecto r and plug the other
end into a convenient 117 - volt ouUet.
5
C UE-MIC- I Switch
Plug a set of headphones in the PHONO
jack provided for monitoring the output, Nor-
mally
the signal from the studio is strong
enough to hear the signal on line gain; if
the signal should be weak, turn the spring
return switch to the CUE position. 'fhe signal
will then be amplified through the BN-68
amplifier to the headphones independent of
whether the line is balanced or un balanced.
This is a spring return switch to assure
operation on MIC-1 position at all times.
Bind i ng P os ts
Three binding posts are mounted on the
back of the chassis, two for the line output
connection and one for ground. The output
connection is made through the telephone
line for renote operatio n.
OPERATION
When the source of power to be used has
been determined, AC or battery, set the amp-
lifier on a convenient surface and adjust the
handle underneath as desired. Then proceed
as follows:
1. If AC power is to be used, plug the
cable connector into the receptacle on the
back of the amplifier and connect to a con-
venient 117-volt ac outlet . Turn the POWER
switch to the AC ON position.
2. If batteries are to be used, turn the
POWER switch to the BATT. TEST position and
check
the VU meter reading. If the reading
is satisfactory, not below 10% less than the
1
00 reading, turn the POWER switch to BATI ON
position.
3. Plug headphones in the PHONO jack pro-
vided for monitoring.
4.
Plug in the microphones; all four re-
ceptacles may be used at one time if desired.
Low impedance broadcast microphones such as
the RCA BK-SA or BK-6 A are recommended. Make
certain that each cab l e on the microphones
selected has a connector, plug XLR-3-1 2C,
MI - 11089A, matching the receptacles on the
BN-6B amplifier .
MAINTENANCE
Fuse Re pla ceme nt
When replac ing a fuse , make sure that the
replacement fuse is of the same type and
r ating , 1/ 16 amp 3AG , slo - blo, as the one
furnished with the amplifier. To use a fuse
of higher rating for replacement purposes
will needlessly endanger the windings of the
power transformer.
Se rvici ng of t he Et che d Wiri ng
Boa rd A ssem blies
The etched wiring boards are made of . 062
inch thick paper base phenolic laminate to
one side of which is bonded a thin sheet of
copper. The conductor pattern is formed by an
etching process. Component leads are threaded
through holes which are punched into the
board. The ends of the leads extending through
the board are bent over against the copper
conductors . The comp l ete assembly is subse-
quently dip-soldered .
Components
may be r eplaced easily by
follo w ing these simple inst r uctions. Care
should
be observed not to break or crack the
board oy undue stress or to damage t be bo n d-
ing adhesive by applying too much heat during
solde ring.
I. T oo ls Required
a. A small (35 watt or less) pencil type
soldering iron .
'
J

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i
6
JI
J2
J3
J4 Fl
JIO El E2
E3
Figure ij - Rear V iew of Amp lifier
BATTERY HOLDER
5 BATTERIES 6.5 EACH
I
94 11 5
I BRACKET
C20
R54 Cl9 R53
FOR COVER
Figure 5 - Battery Tubular Case on Bottom of Chass is

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b. A pair of small diagonal cutters .
c. A pair of small long nose pliers.
d. A sc r ibe or pick.
e. A sma l l knife .
2. E me rg e ncy Repairs
If it is kno wn whi ch component is defec -
tive , it may be replaced w it h out remov i ng the
board
fr om i ts mounting.
a, In t he
case of a sm all compone n t, such
as a 1/ 2 or 1 w
att r esisto r , cut the compon -
ent in half us in g d iag on al pl i ers . Crush t he
body
by means of t he lo ng nose pl i ers. T his
is done to obtai n ex tr a lead le n gth. In the
case of large r compo nen ts , cl ip t he le ad s as
close as possib le to the colJ1P() n ent body .
TO REM CVE D EFE CT IV E CO MD O NENT
CO MP O NENT
CUT Off HE RE
T'.:) INS TALL NEW COMP ONENT
BOARD
BENO WIRE
WIT H PLIERS
TO REMOVE COMPONE NT FROM T OP
OF C IR CUIT BO AR O
SO
LD ER PI GTA I L OF
NEW COMPON EN T TO
LOO P ED ENO,
Figure 6 - Me t hod fo r Re placement
of Componen ts on Print ed Circui ts
7
b. Using lo ng nose pli ers, fo rm a loo p of
the lead ends as shown in fi gure 6,
c. Th read the leads of the ne w component&
t hr ou gh these loops. Cut off the excess lead,
crimp and solder the connectio n.
3. Pe rman e nt R ep ai rs
a. Remove the hardware fastening the board
to the chassis and tilt the board up .
b. Isol a te the defective compo n ent. If it
is necessa ry to discon n ect a component f rom
the circuit for test, heat the Ju n ctio n of
t he compone nt lead and the etch ed w iri ng w ith
the solde r i ng i ron. The heat should be con-
cen
trated on the com ponent lead r ather than
the etc h ed w iri ng pattern . Pry up a nd
st r aighten the be1,t over portion of the com-
po n ent lead with a knife blade, then pull
lead throu gh the hole with Plie rs.
c. To remove the defective component, sn ip
the l eads off at the component side of the
board, see fig u re 6,
d. Using a
small solde ring iron (35 w atts
or less) heat the leads and r emove them fr om
the pri n ted w iring side of the board . Be
care f ul not to apply too much heat or fo r ce
to avoid damage to the thi n copper co nductors.
e. Clean and preform the leads of the new
component and in
sert th rou gh the holes until
the component body is tight agai nst the board.
f. On the circuit si de, grasp the compon-
ent lead and bend it over in the di r ect i on of
the c ir cu it pattern.
g. Crimp the w ire tightly agai ns t the
board (see figure 6), and cut off the excess
co111>one nt lead. Leave about 1/ 16 inch of w ire
protruding fr om the e dge of th e hole.
h. Heat the lead and apply rosin core
solde r . DO N(JI' USE PASTE OR ACID FLUX. Remove
ex cess r osi n from the jo in ts w ith alcoh ol .
i . R ep la ce t he ci r cuit bo ard, us in g the
or
ig ina l hardware.
~. Repl a cement of Tr ans ist or Soc ke ts
Foll ow the sam e pr oced ur es outlined fo r
components.
The ti ny t r ansis t or sockets ar e
mo un ted on to p of the c ir cuit bo ar d.

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8
Voltage Readings
The following table shows the typical voltage to ground readings at the transistor socket
terminal. These readings were obtained with an RCA Voltohm ist . The valu es are approximate and
may vary t:20 %due to production tolerances on transistors. The measurements were made with all
g ain contro ls at zero, plugs P5, P6, P7 and PS in the unit and th e lin e voltage was 11 5v a.c.
VOLTAGE CHART
Transistors Pin
4
Capacitors
(-) Terminal
XQl
-4.2V
cs -15.lV
XQ2
-4.2V C12
-34. 3V
XQ3
-4.2V Cl3 -38.
7V
XQ4
-4.2V C14
-42,9V
XQ5
-11. lV
C15
-2 6.9 V
XQ6
-9.0V C16
-15 .9 V
XQ7
-15.0V Cl8 -34, 3V
XQB
-34,3V
XQ9
0 V
LIST OF PARTS
Sy ,n bol No. Stoel& No. D, awi,.g No.
Desc ription
ATl to AT4 213300 758505 - 2 Resistor:
variable,
c omp., 2 s. 000 ohm t10%, 2
.,,
AT S 213299 7 58 50 5-1 Resistor: variable , comp. , 1 0,000 ohm tl0 %,
2 w
CAPAC I! ORS :
Cl 106114 990130 - 1
ele ct rolyti c , 10
µ.I, 10 V
C2 213301 98 4655- 26
e le c trolytic, l.0 µI, 50 V
CJ 79181 984655 -1 6
electrolytic, 2.0 µ.I, 50 V
C4 213301 984655 -2 6 e
le ctrolytic ,
1.0 µ. f,
50 V
cs
213302 984655 -2 7
electro l yt i c,
so µ.I'
50 V
C6 10611 4
990130-1 el ec trolyti c,
10 µ.f,
10 V
C7
213301 984655-26
electrolytic,
1. 0 µ.f,
50 v
C8
106 114 990130 -1
elect r o ly tic,
10 µ. f , 10 V
C9
21330 l 984655 -2 6
elect ro lyti c, 1.0 µ.f, 50 v
Cl0 106 114 990130 - 1
electrolyti c , 10
µ. f,
10 V
Cll
213301 984 655 -2 6
electro lyt ic, 1.0 µ.f, 50 V
Cl2 21 3304 984655-29
electrolytic, 2 50 µ. f , 50 v
Cl3 to Cl6 21 3303 98 4655 -28
electro l yti c ,
100 µ.f,
50 v
Cl 7
210001
984655-30
electrol ytic , 250 µ.f, 6 V
C l8 213304 984655-29
electrolyti c,
250 µ. f, so y
Cl9 10 6055
990130-10
electro l ytic, 100 µ.f, - 10 +2 50%, 15 V
C20 7918 1
984655 -1 6
electrolytic, 2. 0 µ.f, 50 V
CR1,CR2
210963
Rectifier: germanium ( IN91)
El
to E3 46907 181193-5
Post: bi n ding
Fl
211428 990157 - 102
Fuse: 1/ 16 amp. , 3 AG
Jl to
J4
213288 892 69 59 -1
Co nn ector:
fe m ale , 3 co n t.
J S
to
J8 105783 88288 6- 2 Co
nne c tor :
female, 8 cont.