McCURDY DA504 User manual

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Se
cti
on.
2
3
4
INSTRUCTIONS
OA504
AUDIO
DISTRIBUTION
SYSTEM
I
NDEX.
Subje
ct.
-G
e
neral
Description
Specifications
In
s ta 11
at
ion
Mainten
ance
McCURDY RADIO INDUSTRIES LIMITED
Issue
1
July
1976
Pa
ge
1
of
9,
Page.
3
5
6
9 )
108 CARNFORTH ROA , TORONTO, ONTARIO M4A 2L4 [phone], TELEX 06-9635:
McCURDY RADIO INDUSTRIES INCORPORATED
1051
CLINTON STREET. BUFFALO. N.Y. 14206 [phone] ·
McCurdy
Rad
io
Indus
tries
reser
ves
the
right
,
witho
ut
not
ice
to
make
such
c
hang
es
in
equipment,
desig
n,
specificat
ions,
or
component
'.
as p
rog
ress in
engineering
or
manu
fact
un g tn
ch
niques
may
warrant
to
impro
ve the
performance
of
the
product.

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Figur
e.
1
-1
3-1
3
-2
3-3
AT31O
RG311
RG312
PS855
Instru
ctions
.
LI
ST
OF
ILLUSTRATION
S.
Tit
le
.
Page.
Block
Diagra
m 4
Frame La
yout
7
Frame Wi
ring
8
AT31O
Con
n
ecto
r Wi
ring
8
SUB
ASS
EM
BLY
INSTRUCTIONS.
Au
dio
Distributio
n
Amplifier
Remote Gain
Di
stribution
A
mplifier,
Opt i
onal
Remo
te
Gain Dis
trib
ut
ion
Amplifie
r,
Optional
Power
Supply
Index.
Page 2.

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..,.
·l
DA
5
04
In
s
truc
t i
ons.
Sec
tion
1.
GE
NE
RAL
DES
CRI
PTI
ON
.
Section
1
1.01
to
1.06
1.
01
The
DA5
04
Au
di
o D
istri
bu
ti
on Sy
st
em
is
desi
gned
for
audio
distribution
in
br
oa
dcas
t i ng
or
ot
h
er
commerc
ial
a
pplicati
ons w
here
pr
o
fessional
qua
lit
y must be
mainta
i
ned.
The
DA504
con
sis
t s
of
an FR906
i9-inch
equipme
nt
Frame h
olding
up
to
s ix
AT31
0 Dist
ri
bu
ti
on
Amplif
i
ers
and one
PS
855 Power S
up
p
ly.
1. 02 Each
AT3
10
br
i
dges
one i
np
ut
at
a
ny
spe
cifi
ed le
vel
from -12dBm
to
+20d8m
a
nd
prov i
des
up
to
22
iso
la
ted
out
pu
t s
at
+8dB
m,
600 ohms ,
balanced.
T
we
lv
e
of
t h
ese
ou t
puts
are
prov
ided wi t
hin
th
e
am
p]
ifiers
and
provision
is mad e f
or
t he a
ddi
t ion
of
up
to
te
n
externa
l
outputs.
Thu s , a
complete
c
om
ple
me
nt
of
s ix
am
p]
ifie
rs
can
p
ro
vide 132 o
utp
ut s from
six
inputs
,
72
int
erna l and
60
exte
rn
al
. See
AT
310
instru
c t ion s
for
further
informati
o
n.
1
.03
A pre se t
gai
n
cont
ro l is p
ro
vi
ded on
the
fron
t pane l
of
each
AT
310
di
s
tributi
on a
mpl
ifier.
Th
is
cont
ro l w
ill
va
ry
th
e g
ain
from
O
up
to
the
max
im
um
av
ai
l
able
.
1. 04 Each
AT31
0 is
also
equippe
d
wit
h a
sum
ming
input,
a
llowin
g
it
to be
use
d
with
sw
itc
h
ers,
or
ot
h
er
syste
ms, hav
ing
th
e
insolati
on ne tw
orks
built
in.
1
.05
An
RG311
or
RG3
12
remote
gain
distr
ibution
amp
li
f
ier
is
av
ai
la
b
le
in
pl
ace
of
the
AT
3
10
.
These
amp] i f i
ers
provid
e f
or
remote
DC
control
of
amplifi
e r
gain.
The rem
ote
gai
n
sec
t i
ons
of t h
ese
amp] i f
ie
rs a re
also
ava i l abl e
se
pa r
ate
ly , a l
lowing
fi
el
d
conver
sion
of
AT310
a
mplif
ie
rs
to
rem
ot
e ga in
at
any
time.
See AT3
10
in
s
tructi
ons f
or
furthe
r
information.
1.
06
The
FR90
6 equi pm
~nt
Frame
mo
u
nts
in a
sta
ndar
d 19
inch
r
ack
or
pedesta
l
and
occupies
onl y 5.
25
i
nches
of
vertic
a l spac
e.
Page 3

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Qi
<.Cl
(1)
.&:-
FEEDBA
CK
GA
IN
i,5
,
19
REMO
TE
GAI
N
j B,
16
,18
1----
1
-·------
--
I
I
INPU T
~
I
~
SUMMI
NG~
I
INPUT ' I
I
I
I
I
I
I
AT
310
AMP
LI
FIER
Al -
41
6
50
/60
I ,3,14
115V
D
H, (
..,...
__
__
_
RE
MO
TE
GAIN
AM
PU
Fl
ER
~
- - -
--
--
(OPTIONAU
RE
G
UL
ATOR
C
+
PS655
POWER
SUP
P
LY
GAIN
-1
I
6
1,62
::J
~}EX
TE
RNAL
SPLITS
.JVVVL.-
(IOMAX)
63,64
>----21,23
>----21
,29
>----3
3,
35
>----,9,41
>-
--
45,47
>----5
1
,53
>----24,26
>----
30
,32
~
I
>---
36 ,38
~
/
>----
4
2M
/>----4
8,50
I
>----54
,
56
IN
TER
NAL
SPLITS
/
>----
57,59
DIRECT OUT
PUT
I
Figure
1-1.
B
lock
Diagram
0
)>
V,
0
..c--
:::i
V,
rt
•
C
n
rt
0
:::i
V,
-.,
Ul
-·
(l)
(0
n
C
rt
, -·
(l)
0
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D
A504
In
str
uction
s .
Se
ctio
n 2. SPECIFICATIONS.
2.01
Frequency
Response:
±0
..
25dB
, 20Hz
to
2CkHz
(Reference
1 kHz).
2.02
Input
Leve
l:
-12d8m
to
+20d8m ,
max
i
mum.
2.03
Gain:
Section
2
2.01
to
2.15
Var
iab
le
from
Oto
20dB
by
means
of
preset
cont
rol.
Maximum
gain
of
4
0dB
with
820
ohm
f
eedback
resi
st
or
.
2.0
4
Output
Splits:
Ma
ximum
22 pe r
am
pl
if
ie r . Twelve
provid
ed ,
up
to
10
e
xternal
possible.
2.05 Outpu t
Le
ve l :
+8dBm,
+25
d8
m maximum.
2.06
Source
Impedance:
600
ohms
balanced
.
2.07
Inpu t
lm
pde
ance:
20k
ohms
or
summ
ing,
balanced.
2
.08
Output
Impedance:
600 ohms ,
bala
nced .
2.09
Load
Im
pedance:
600 o
hm
s , bal
anced,
minimum.
2.
10
No
ise:
90d 8 below
+18dBm
ou'tput,
from
10Hz
to
lOOkH
z,
depending
on
gain
setting.
2.
11
Dis
tortion:
L
ess
than
0.2
%,
20H
z
to
20kHz
at
+18d8m out .
L
ess
than
0.25
%,
20Hz
to
20k
Hz
at
+25dBm
out.
2
.12
O
utput
Spli
t
iso
latio
n:
Better
th
an
70d B, 2
0H
z
to
20kHz (80d8
typical
mid-band).
2.
13
P
ow
e r Requ
ir
eme
nt:
115V
, 50/60H
z,
approx
i
mate
ly
12
0VA
(230V
avai
l
able).
2.
14
Di
me
nsi
ons
:
5
.2
5 in.
(13.34
c
m)
Hi
gh,
13 i
n.
(3
3
cm
)Deep,
19
in.
(48.26
cm)
Wide.
2.
15
We
ight:
A
pproximately
30 pound
s,
(13
.6
kG
).
Page
5.

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DA504
Instruction s .
Section 3
3.01 to 3.07
Section 3
INSTALLATION.
J.02
3.03
3.0 4
3. 05
3.06
3.07
On rece i pt of the equi pm ent, examine each un i t for any damage that
may have occurred in t ra nsit. If crny damage is found, report it in
accordanc~ with the enclos ed Damage Claim Pr oce dure Form.
Under so
me shipping cond itions, the power supply and amp] ifier
modules will be removed from the frame and packed separately. Install
these after al I othe r insta ll at io n is complete.
Mounting . .
The
DA504 occupies 5-1/4" of ve rti c al space in a s t andard 19" rack.
The unit generates ve ry li t tle heat and so the frame may be stacked
as required. However, a void pro x im i ty to equipment that generates
considerable heat . F urther, the DA504 should be mo unted at least 3½"
above or below power su pplies or transformers in o rder to avoid hum
pick-u p.
Installation Co nnecti ons .
Ref
er to fi g ur es 3- 2 and 3 -3 for terminal numbers.
Audio Wiring.
Audio runs should co ns is t o f shielded, twiste d pairs such as MRI SA12002.
Keep
input and output a udio runs we! 1 separated from each other and from
ac power w1r1 n g. Audi o wiring should be dressed neat l~ and arranged in
harnesses by func t io n a nd lev e l (inp ut wiring, output wiring etc.). Do
not lace together pa i rs of more than 28dB differ e nce in level.
In pu t Wiring .
Input wi ri ng should e nt e r a t the top right of the frame as viewed from
th e rear. In p ut wi re s a re to be soldered directly to the AT310 connector
terminal s loc a ted on the re ar panel . Wire the shield to pin 5-
NOTES. (1) To m~int ain proper phasing between inp uts and outputs where
this is important, phasing is shown on Figure 3-3.
(2) Shields s hould be grounded at the designated terminals on
the DA504, provided they are not grounded at the far end.
Do not g round shields at both ends of a run.
Output Wiring.
Outputs are wired dir e ct ly to the te r minals on the AT310 connector as
shown i n figures 3-2 a nd 3-3 . Cables should exit from the bottom right
of the frame as viewed f rom the rear. The output shields should be wired
to the comm on bus runnin g through pi ns 67 and 68 of the connector.
A ltern at e ly, the ou tp ut s hield s ca n be wired to the ter minals designated
with an asteri sk on Fig ur e 3-3. If this is done, these terminals must be
connect ed to the com mon bus. Unused outputs should be left unterminated .
Page 6.

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:,,
.,
"
DA50
4 I
nstructions
Section
3
3.08
to
3-
13
3.
08
If a
ddi
t i
onal,
external,
output
sp
lit
s
are
req
uir
e
d,
the
se
are
wired
to
pins
57 and 59 on
amplifier
con
n
ec
to
r.
The
11
pos
i t
ive
11
ph
ase
should
be
connect
ed
to
p
in
57
and t he
11
negative
11
phase
to
pin
·
59.
Th
e
resistors
used
f
or
th
e
ex
te
rnal
splits
should
be 300 oh
m,
1W,
±5
%
car
bon
film
types.
3.09
Gr
o
undin
g.
Run
a N
o.
16
stranded,
in
su
lat
ed w
ire
f r
om
the
grou
nd
(common)
bus
on
3.
10
3.
11
3.
12
3.
1
3
the
termina
l
strip
to
s
yst
em g
round
(Fig
u
re
3-2).
Ac
Power .
(a)
The
DA504
ac
power
cord
plug
s
in
to a 115 vo
lt,
50/60Hz
ac
sourc
e.
Keep
this
c
ord
separated
f
rom
th
e
audio
l
eads
.
(b)
Th
e
DA
504
may
be
ope
r
ated
from a 230
volt
50/60Hz
ac
sour
ce
if
th
e power
transfo
rm
er
st
rapping
is
charged
. See PS855 power
s
up
ply i
nstruct
i
ons
.
If
the
abov
e wi
ring
reco
mmendations
ar
e
fol
lowed
the
system
should
mee t
al
1
th
e
performa
n
ce
speci
ficat
ion
s
of
Section
2.
lnst
a l
ling
Modu
l
es
in
Fram
e.
lnstal
1
the
amp
l
if
i
ers
and power
su
pp
ly
into
the
DA504
frame
in
a
cco
r
dance
with
th
e l
ayo
ut
of
Figure
3- 1.
Be
carefu
l
not
to
dam
age
the
PC
boards
or
connectors.
Final
Level
Adj
ustment.
After
in
stallation,
refer
to
the
AT3
10
instructions
and
set
up
the
gains
of
the
amp
lifi
ers
as
directed.
te------
--------
---
19
"
-------
-
----
----------
r 0
5 1/4"
L0 * *
AT3
1O
AT
31O
A l
A2
A
UDIO
DISTRIBUTION
SYSTEM
* * * *
AT3
1O
AT31O AT31O
AT31O
A3
A4
A5
A6
DA5O4
FRAME FRONT
VIEW
*
UP
TO
SIX
AMPLIFIERS INSTALLED AS PER
CUSTOMER
REQ
U
EST.
Fig
ur
e 3-
1.
Frame
Layout
0 0
0
FUSE®
$0FF~ON
0 0
PSB55
~
Page
7-

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..
DA5 04 Instru c t i ons
------
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RAMP C ON TR OL
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SPLIT
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SPLIT 8 [: _
SPLIT 9
SPLIT 10
SP LIT II
SP
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- 25 V -
CHA SSIS
Section 3
Fi gures 3-2 & 3-3
INPUT
EXT. FEE08ACK GAIN
-= ~] DI RECT OOTPUT
+25V
COMMON
VIEWED FROM WIRI NG SIDE , REA R OF CONNECTOR
Figu re 3-3. AT310 Connector
Wi ring
JU M P[R A(l.tOV[O If
IS0LA11"0 G IIOUlm
15 R(OU IR (O
TO 5TATIO H
_ S 'l' ST( M
• G ROUN O
Fi gu re 3-2. Fra me Wi ring
~
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Page 8

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DA504
In
struction
s ·
Section
4
MAINT
E
NANC
E.
S
ec
ti
on
4
4.
01
t o 4
.0
2
Ta
ble 4
.01.
4.01
The
DA5
04 shoul d be
inspected
dur ing
reg
ul
ar
ma i
nte
n
ance
periods
.
Remove
accumulated
dus t
by
means
of
a s
oft
non-meta
l
1
ic
b
rush
or
a
vacuum
clea
n
er.
WARN
I
NG.
A
LW
AY
S
SHUT
OF
F
THE
AC
POWER
WHEN
WORK
I
NG
ON
THE
EQU
I
PMEN
T.
DO
NO
T
REMOVE
OR
RE
PLA
CE
MODULES
WHEN
POWER
IS
APPLIED
TO
THE
EQUIPMENT.
4
.02
The a
mplifi
e r and power suppl y
modu
l
es
may
be removed and ben
ch-
t
es
ted
separ
ate
ly
if a
faul
t is sus
pected.
Refer
to
t
he
se
p
arate
instructi
ons
for
th
ese
un
it
s.
Table
4.01.
Parts
List.
Re
fe
r
ence
Designation
Suppli
e r and
Pa
rt
No.
Desc
ripti
on
.
.
----4------+--
---l
A1
to
A6
PS
I
J
1
to
J6
J7
McCurdy
AT310
McCurd
y PS855
ED
AC
345-0
7
2-500-808
Ampheno
l
26-
1
90-
16
C
ords
of
Ca
nada
3/18
Di
st
ribution
Ampli
fi
e r
Powe
r S
up
ply
Con
ne
ctor
:rece
pt
ac
le
;
-:,-~
fe
ma
le co
ntr
act
s.
Conne
ctor:
rece
ptacl
e;
16
f
em
ale
con
tac
ts.
Cab le &
Plug
As
se
mb
ly
ac
po
w
er.
Page
9-

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Section
2
3
4
5
6
INSTRUCTIONS
AT310
DISTRIBUTION
AMPLIFIER
INDEX
Subject
General
Description
Specifications
Installation
Circuit
Description
Maintenance
Parts
List
LIST
OF
ILLUSTRATIONS
&
DRAWINGS
Number
Figure
3-1
Figure
3-2
Dwg.
B-310/2-3
Dwg.
D-310/2-1
Dwg.
C-310/8-1
Dwg.
c310-30/8-1
Dwg.
B-310/1-2
Title
Connector
Wiring
Feedback
Resistor/Gain
Table
Block Diagram
Schematic
Diagram,
AT310
& AT310-30
Component
Layout,
AT310
Component
Layout,
AT310-30
Test
Setup
McCURDY RADIO INDUSTRIES LIMITED
108 CARNFORTH ROAD, TORONTO,
ONTARIO
M4A 2L4
(416)
751-6262, TELEX 06-963533, TWX 610-492-1373
McCURDY RADIO INDUSTRIES INC.
1711
CARMEN DRIVE, ELK GROVE VILLAGE, ILLINOIS 60007,
(312)
640-7077, TWX 910-222-0436
Issue
4
September,
1980
Page 1
of
17
Page
2
3
4
7
10
15
Page
6
6
8
9
12
13
14
Mccurdy
Radio Industries reserves the right, without notice
to
make such changes in equipment, design, specifications,
or
components
as progress in engineering
or
manufacturing techniques may warrant to improve the performance of the product.

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AT310
Instructions.
Section
1
GENERAL
DESCRIPTION.
Section
1
1.01
to
1.08
1.01
The
AT310
is
a
high
quality
audio
distribution
amplifier
providing
up
to
22
isolated
outputs
at
+8dBm, 600 ohms,
balanced,
from
one
input.
The
input
circuit
permits
bridging
of
input
levels
from
-12d8m
to
+20d8m,
thereby
covering
most
requirements
in
broadcast
and
similar
professional
applications
for
distribution
amplifiers.
1.02
Twelve
of
the
possible
22
outpu
_
ts
are
provided
within
the
amplifier
and
provision
is
made
for
the
addition
of
up
to
ten
external
outputs.
1.03
The
AT310
is
also
equipped
with
a summing
input,
allowing
it
to
be
used
with
switchers,
or
other
systems,
having
the
isolation
networks
bu
i 1t
in.
1.04
A
preset
gain
control
is
provided
on
the
front
panel
of
each
AT310
distribution
amplifier.
This
control
will
vary
the
gain
from O up
to
the
maximum
available.
1.05
Provision
is
made on
the
AT310
for
installation
of
an RG310-1
or
RG310-2
remote
gain
control.
Installation
of
either
of
these
units
allows
remote
DC
control
of
amp]
ifier
gain.
See
Section
3
for
installation
instructions.
1.06
Al
1
circuitry
is
silicon
sol
id
state
and
is
assembled
onto
a
glass-
epoxy
printed
circuit
board
fastened
to
a
metal
stiffener
plate.
The
complete
assembly
plugs
into
an
FR906
19-inch
equipment
frame,
the
DA504
Audio
Distribution
Assembly
or
an
individual
72-pin
edge
connector.
1.07
The
AT310
is
used
mainly
in
the
DA504
Audio
Distribution
Assembly,
but
may
be
used
in
other
applications
where
a
high-qua]
ity
distribution
amplifier
is
required.
1.08
The AT310-30
is
identical
to
the
AT310
with
the
exception
that
it
is
designed
to
be
used
with
30K
ohm
input
bridging
resistors.
Page 2

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AT310 Instructions.
Section 2 SPECIFICATIONS.
2.01 Frequency Response:
±0.25dB, 20Hz to 20kHz (Reference 1kHz).
2.02 Input Level:
-12dBm to +20dBm, maximum.
2.03 Gain:
Section 2
2.01
to 2.14
Variable from Oto 20d8 by means of preset control. Maximum gain
of 40dB with 820 ohm feedback resistor.
2.04 Output Splits:
Maximum 22. Twelve provided on amp! ifier, up to 10 external.
2.05 Output Level:
+8dBm, +25dBm maximum.
2.06 Source Impedance:
600
ohm balanced.
2.07 Input Impedance:
20K ohms or summing, balanced.
2.08 Output Impedance:
600 ohms,
balanced.
2.09 Load Impedance:
600 ohms, balanced minimum.
2.10 Noise:
(lOHz to lOOkHz) 90dB below +18dBm output, at unity gain. Noise
figure depends on gain setting.
2.11 Distortion:
Less than 0.2%, 20Hz to 20kHz at +18dBm out.
Less than 0.25%, 20Hz to 20kHz at +25dBm out.
2.12 Output Split Isolation:
Better than 70dB, 20Hz to 20kHz (80dB typical, mid-band).
2.13 Power Requirements:
±25V DC, 600mA maximum.
2.14: Dimensions:
1-3/4
11
(44.Smm)wide, 4½
11
(112mm) high, 10
11
(255mm) deep.

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AT310
Instructions.
Section
3
3.01
to
3.08
Section
3
INSTALLATION.
3.01
3.02
3.03
3.04
3.05
3.06
3.07
3.08
On
receipt
of
the
AT310
distribution
amp]
ifier,
examine
it
for
any
damage
that
may
have
occurred
in
transit.
If
any
damage
is
found
report
it
in
accordance
with
the
enclosed
damage
claim
procedure
form.
The
AT310
plugs
into
the
FR906
equipment
frame
which
occupies
5-1/4
11
of
vertical
space
in a 19
11
rack.
The
ampl.ifier
generates
very
little
heat,
therefore,
the
frames
may
be
stacked
.as
required.
However,
avoid
proximity
to
other
equip
me
nt
that
generates
considerable
heat
or
to
power
transformers,
which
may
cause
hum
pickup.
When
the
AT310
is
not
to
be
mo
unted
in
the
FR906
equipment
frame,
a
72-
pin
edge
connector
(EDAC
345-072-500-808
or
equivalent)
will
be
re-
qu
ir
ed
to
mate
w
ith
th
e
PC
board.
All
connections
to
the
amplifier
are
made
to
this
edge
connector,
either
mounted
in
an FR906
frame
or
mounted
separately.
Refer
to
Figure
3-1
for
detailed
terminal
numbers.
Po
we
r
Wiring:
If
the
amp]
ifiers
are
1n
a
system
frame
being
fed
from a
common
power
supply,
all
+25V
terminals
(pins
65 & 66)
may
be
bussed
together,
all
-25
V
terminals
(pins
69 & 70)
may
be
bussed
together,
all
common
terminals
(pins
67
& 68)
may
be
bussed
together,
and
all
chassis
terminals
(pins
71
&
72)
may
be
bussed
together.
A
16
gauge,
stranded,
insulated
wire
should
be run from
the
common
bus on
the
AT310
connector
to
system
ground.
Th
e
chassis
terminal
or
the
AT310
connector
should
be
connected
to
the
frame,
or
associated
chassis
by
a
short,
20
gauge
sol
id
wire.
Audio
Wiring:
Audio
runs
should
consist
of
shielded,twisted
pairs,
such
as
MRI
SA12002.
Keep
input
and
output
audio
runs
well
separated
from
each
other
and from
AC
power
wiring.
Audio
wiring
should
be
dressed
neatly
and
arranged
in
harnesses
by
function
and
level
(input
wiring,
output
wiring,
etc.).
Do
not
lace
together
pairs
of
more
than
28dB
difference
in
level.
Page
4 .

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AT310
Instructions
Section
3
3.09
to
3.17
3.09
3.
10
Where
it
is
important
that
t ·1e
outputs
be
in
phase
with
the
input,
the
correct
phasing
is
indic
j
ted
on
Figure
3-1 by
a+,
which
indicates
the
11
high''
side
of
the
line.
Ground
the
audio
shields
onl
y
at
one
end
of
the
run,
preferably
at
the
AT310
connector.
The
input
s
hield
should
be
connected
to
pin
5 and
the
outputs
shields
to
the
grou
n1
bus,
pins
67
&
68.
Alternately,
the
output
shields
can
be
wired
~o
the
terminals
designated
with
an
asterisk
on
Figure
3-1.
If
this
is
d 1
ne,
these
terminals
must
be
connected
to
the
common,
ground,
bus.
3.
11
When
more
than
twelve
outputs
are
required,
up
to
ten
additional,
external
outputs
may
be
wired
to
the
d
irect
output.
A 300 ohm, ¼ Watt,±5%
isolating
resistor
should
be
used
in
each
side
of
each
output.
Refer
to
Figure
3-1
for
the
proper
pi
n numbers and
phasing
3.
12
3.
13
3.
14
3.
15
3.
16
:3
.
17
In
all
normal
applications,
~
onnector
pins
61
&
63
are
connected
together
and
pins
62 &
64
are
connect
ed
together.
All
unused
outputs
may
be Je; t
unterminated.
If
the
above
wiring
recommend
ations
are
fol
lowed,
the
system
should
meet
all
the
performance
specific~tions
given
in
Section
2.
Final
level
adjustment:
After
the
amplifier
is
insta
l
led,
the
gain
should
be
adjusted
to
the
level
required
by
means
of
t he
preset
gain
control
on
the
front
of
the
guide
plate.
As
supplied,
t ~e AT310
has
a maximum
gain
of
20dB. A
feedback
resistor
may
be
useJ
to
obtain
a
maximum
gain
of
40dB.
See
Figure
3-2
for
selection
of
the
proper
feedback
resistor.
A
preset
gain
control,
R20A,
is
provided
in
series
with
the
main
gain
control,
R20.
This
control
:
nay
be
used
to
set
the
gain
of
the
amplifier,
thus
preventing
accidental
cJtting
of
amplifier
gain
with
the
front
panel
control.
When
the
gain
is
ajjusted
with
the
preset
control,
R20A,
the
front
panel
control
R20,
ca
n
only
decrease
the
gain
by
a
predetermined
amount.
lnstal
lat
ion
of
Remote Gain ~
mpl
ifiers
RG310
- 1
or
RG310-2.
Refer
to
Dwg.
D-310/2-1
and ~o Remote
Gain
Amplifier
Instructions
for
identification
of
points
men
~
ioned
in
the
fol
lowing
procedure.
(a)
Remove AT310 from
guid
~
plate
by
removing
four,
4-40
machine
screws.
(6)
Remove
Integrated
circ
,
Jit
IC3
from
socket
and
resis
t
or
R19
from
PC
board.
(c)
Mak
e
sure
holes
in
PC
,
oard
numbered 1
to
9
are
open
(free
of
solder).
(d)
Make
sure
the
nine
bar~
wire
l
eads
on
the
Remote Gain
Amp]
ifiers
are
straight
and
install
sp
acers
(supplied
with
Remote Gain
Amp]
ifier)
at
points
A3
,8,and
9.
(e)
lnstal
1
Re
ll'
te
Gain /\mt, 1
ifier
on AT310
board,
so
that
all
leads
are
Page
5

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AT310
Instructions.
Section 3
3. 17
(e)
(f)
(g)
3.. 17 to 3. 18
straight, solder connections and clip off excess leads.
Install shielded cables
1C1 and 1E1,
Dwg. C-310/8 - 1. These
cables are supplied with the remote gain amp] ifier.
Refer to Remote Gain Amp! ifier instructions for sp~cifications
and other data.
'}. 18
The AT310-30 is installed the same as the AT310 except that the audio
input must be connected to pins 1 and 3 through external 30K ohm
bridging resistors.
* CONN E CT TO
COMMON FOR
l,.P~.OVEO JSULATON
00 OU TPUT SPUTS
CONTROL
KA MP CONTROL
RAMP
CONT COM
5V REF .
"'
SPLIT 7 [:
•
I(
SPLIT 9 [
+_
..
: ] SUMMING iN PUT
SH1ELi)
: ] 20k!l INPUT
SHIELD
EX T. FEEDBACK GAIN
EXT . FEE O BAC:< GAIN
:] SPLIT I
..
:] SPLIT 2
..
:] SPLIT 3
•
:] SPUT4
AMPLIFIER GAIN RESISTOR
20dB
OPEN
25dB 12k ohm
VALUE
SPLIT 10 [:
f(
r+
SPLIT II L- "
30dB
4300
ohm
"
SPLIT 12 [:
•
+25V
COMMON
-25V
CHASSIS
+,J
_ SP LIT 5
•
:] SPLIT 6
..
+l
_JDIRECT OUTPUT
+25V
COMMON
-2 5V
CHASSIS
VIEWED
FROM WIRlt;G SIDE, REAR CF CONNECTOR
Figure 3-1
Connector Wiring
35dB
1800 ohm
40dB
820 ohm
Figure 3-2.
Feedback Resistor/Gaintable
Page 6

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AT310
Instructions
Section
4
4.
01
to
4.
09
Section
4
CIRCUIT
DESCRIPTION
.
4.01
The
circuitry
of
the
AT310
is
shown on
Dwg.
D-310/2-1,
and
1n
simplified
form,
on
Dwg.
B-310/2-3.
4.02
4.03
4.04
4.05
4.06
4.07
4.08
4.09
The power
supply
section
of
the
AT310
provides
an
accurately
regulated
and
filtered
±15V
DC
for
the
input
stages
and
optional
remote
gain
amplifier
from an
input
of
±25V
DC
.
Integrated
circuit
regulators
IC4
and
IC5
are
used
for
this
function.
Power
for
the
output
stage,
Q24-Q27,
is
taken
directly
from
the
±25V
DC
input.
An
RC
filter
is
used
to
provide
power
to
the
driver
section
of
the
output
amplifier.
The
input
amp]
ifier,
consisting
of
ICI,
IC2
and IC3,
provides
a
balanced,
summing
input
and an
unbalanced
output
to
level
control
R20.
Two
inputs
are
provided,
one
with
built-in
10k
ohm
bridging
resistors
and
the
other
direct,
without
resistors,
for
use
in
applications
with
external
resistors
(switcher
crosspoints,
etc.).
When
the
optional
Remote Gain
Amplifier
is
installed,
IC3
and
R19
are
not
used.
The
remote
gain
module
provides
the
connections
between
ICI,
IC2
and
the
level
control.
An
amplifier,
consisting
of
Q1-Q3,
providing
external
feedback
gain
control
follows
the
gain
control,
R20. The
external
feedback
resistor,
connected
between
pins
15 and
l9
on
the
edge
connector,shunts
the
internal
resistor
R25,
which
decreases
the
amount
of
feedback
applied
around
the
amplifier,
therefore,
increasing
the
gain
The
direct-coupl
ed,
complimentary-symmetry
output
amplifier,
cons
isti
ng
of
Q4-Q27 and
associated
components,
fol
lows
the
feedback
gain
amplifier
stage
and
provides
the
power
amplification
necessary
to
drive
the
output.
The
amplifier
output
is
coupled
directly
to
the
edge
connector
before
being
fed
to
the
output
splits
to
allow
for
the
insertion
of
an
output
transformer
or
other
special
circu
i
try.
Twelve
balanced
600
ohm
output
splits
are
supplied
on
the
amplifier,
along
with
one
direct
output.
Up
to
ten
external
600
ohm
outputs
may
be
wired
to
the
direct
output.
Page 7

www.SteamPoweredRadio.Com
{:
Jli%h
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DO
NOT
SCALE
REG
r---------------
N I
I')
IOK(l
1
I
I
I
I
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RG
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I
REM.
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I
OPTION
I
SUMMING/INPUT
AMP
L-7--_J
I
I
~
------
___________
J
NOTE:
AT310
WITH RG3IO-I
BECOMES
RG311.
TOLl'.RANCE
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UNIT--
TORONTO
•
ONTARIO
AT310
DISTRIBUTION AMPLIFIER
SCHEMATIC
DRAWINQ
No.
B
310/2-3

www.SteamPoweredRadio.Com
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3nss1

www.SteamPoweredRadio.Com
AT310 Instructions
Section 5
5.81
to 5.06
Section 5 MAINTENANCE
5.01
5.02
5.03
5.04
5.05
5.06
The AT310 should be inspected for damaged or deteriorated components
and
wiring during regular maintenance periods. Remove accumulated
dust by means of a soft non-metallic brush or vacuum cleaner.
When removing or replacing components, be careful not to damage the
printed circuit board, wiring or other components. Use a 25-Watt
fine-point, temperature-controlled soldering iron and resin-core solder
onl y. Refer to Dwg. D-310/2-1 for the component la y out of the AT310
and AT310-30 distribution amplifiers.
The fol lowing test procedures check that the AT310 is functioning
properly and provide a means for setting ~p the unit for initial
operation.
The test equipment should be of the type specified, or equivalent, and
set up as shown on Dwg. B-310/1-2.
a) Audio Generator: Amalgamated Wireless G231.
bJ Distortion Analyzer: Hewlett-Packard HP334A.
c) Oscilloscope: Hewlett-Packard HP1200B.
d)
Electronic Voltmeter: Fluke 8000A.
e)
Isolation Transformer: Hewlett-Packard HP11005A.
f) Edge Connector: EDAC 345-072-500-808.
g)
h)
i )
620 ohm, ½W,
620 ohm, ¼W,
820 ohm, ¼W,
+5 %
+5%
+5 %
resistor.
resistor.
resistor.
A well filtered, regulated, power supply capable of delivering +25
volts DC at 600mA, maximum should be used. A Mccurdy PS855 is
recommended.
DC Adjustments:
For the DC adjustments, the test equipment should be set up as shown
on
Dwg. B-310/1-2.
a) Centre-point voltage setting:
1) Set the output of the audio generator to O (off).
2) Connect the voltmeter between the output, pin 61, and common,
pin 67.
3) Adjust R38 for OV, +5mV at this point.
4) Move the voltmeter lead from pin 61 to pin 62.
5)
Adjust R41 for OV, +5mV, at this point.
b) Quiescent Current setting:
1) Set the output of the audio generator to O (off).
2) Connect the voltmeter across R84.
3)
Adjust R36 for a reading of 30-35mV.
4)
Connect the voltmeter acro ss R84 and adjust R37 for the same
reading.
c) After completing steps a and b, allow the AT310 to idle for
approximately 15 minutes, then repeat the adjustments.
Page 10

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AT310
Instructions.
Section
5
5.07
to
5.11
5, 07
Ga
in
Test:
5.
08
5.09
5.
1O
5.
11
a)
Set
up
the
test
equipment
as
shown on
Dwg.
B-310/1-2.
b)
Set
R20,
the
front
panel
gain
control,
fully
clockwise
and
R20A
fully
counter-clockwise.
c)
Set
the
aud io gene
rator
output
to
-20dBm
at
lkHz,
600
ohms
balanced.
d) Read
the
output
level
on
the
distortion
analyzer.
It
should
be
+20dBm, minimum .
e)
Remove
the
820
ohm
feedback
gain
resisto~.
f)
Read
the
output
level,
it
should
be
OdBm,
minimum.
Distortion
Test:
a)
Set
up
the
test
equipment
as
shown
on
Dwg.
B-
310/1-2.
b)
Remove
the
820
ohm
feedback
gain
resistor.
c)
Set
the
audio
generator
output
to
OdBm
at
lkHz , 600
ohms
balanced.
d)
Adjust
gain
control,
R20,
for
an
output
of
+18dBm.
e)
Read
the
amount
of
distortion,
it
should
be
less
than
0.2%.
f)
Repeat
steps
c ,
d,and
eat
20Hz, and 20kHz
keeping
the
input
and
output
levels
the
same. The
distortion
should
remain
less
than
0.2%
g)
Set
the
audio
generator
output
to
+18dBm
at
lkHz , 600
ohms
balanced.
h)
Adjust
gain
control
R20
,
for
an
output
of
+18dBm.
i)
Read
the
amount
of
distortion,
it
should
be
less
than
0.2
%.
j)
Repeat
steps
g,h
and
i
at
20Hz, and 20kHz
keeping
the
input
and
output
levels
the
same. The d i
stortion
should
remain
below
0.2
%
k)
Set
the
audio
generator
output
to
+18dBm
at
lkHz,
600
ohms
balanced.
l)
Adjust
the
gain
control,
R20,
for
an
output
of
+25d~m.
m)
Read
the
amount
of
distortion.
It
should
be
less
than
0.25%.
n)
Repeat
steps
k,
l,
and
mat
20Hz
and 20kHz,
keeping
the
input
and ou
tput
levels
the
same. The
distortion
should
remain
below
0.25
%
Frequency
Response
Test.
a)
Set
up
the
test
equipment
as
shown on Dw
g.
B-310/1 -
2.
·
b)
Remove
the
820 ohms,
feedback
gain
resistor.
c)
Set
the
audio
generator
output
to
-lOdBm
at
1kHz, 600 ohms,
balanced.
d)
Adjust
the
gain
control,
R20,
for
an
output
of
+8dBm.
e)
Sweep
the
generator
from
20Hz
to
20kHz,
the
output
should
remain
within
±0.25dB
of
that
at
1kHz.
Final
Step:
Leave
the
gain
cont
r
ol
as
set
under
test
5-09
,
Refer
to
3.15
and
3.16
for
the
final
level
adjustment
as
installed
in a
system.
This
completes
the
test
procedures.
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