McMartin AMR-1 User manual

STEAM POWERED RADIO.COM
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instruction
ma ual
AMR-1
RECEIVER
-
,

STEAM POWERED RADIO.COM
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MCMartin.
MCMarti~
AMR-1
RECEIVER
INSTRUCTION MANUAL
page
I TECHNICAL SPECIFICATIONS
1
11 GENERAL DESCRIPTION
1
Ill INSTALLATION
1
IV CIRCUIT DESCRIPTION
1
V TROUBLE SHOOTING
PROCEDURE
2
VI PARTS LIST
3
VII SCHEMA TIC DIAGRAM
4
WARRANTY

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MC Martin.
TECHNICAL SPECIFICATIONS
FREQUENCY
RANGE .. ......... .
ANTENNA INPUT ..
. .. . .. 540-1620 kHz, fixed tuned to
specific frequency
. .
.. . .75 ohms nominal unbalanced
(BNC
type connector )
SErJSITIVITY...... . . 30 microvolts for 20 dB SIN ratio
SENSITIVITY FOR
CARRIER FAIL
OPERATION . . . .. .
AGC.
... . ... . .... .
AUDIO
FREQUENCY
RESPONSE. ... . . . .
HARMONIC
DISTORTION . .... .
NOISE
LEVEL. . .. .
at 30% modulat io n
.
......... 100 microvolts minimum
...... . .... . ... . . ... ...... 60 dB
..... ±1.0 dB , 50-5000 Hz; ±3 dB ,
5-10 kHz
.... less than 3% at 90% modulation
.
.... .45 dB or greater below 100%
modulation
with 10 mV input
SELECTIVITY..... . ......... ±10 kHz, at 6 dB points
AUDIO OUPUTS... 600 ohms balanced at O dBm and
600 ohms unbalanced
at 1. 0V rms
POWER
REQUIREMENTS... . .. . .. . 115 Vac, 50/60 Hz, 6 watts
DIMENSIONS . . . . . . . .............. 1¾" (4.45 cm) H x
19" (48.3 cm) W x
5" (12 .7 cm) D
FINISH . . . . . . . . . . . . ............ McMartin beige with
wood grain trim
II GENERAL DESCRIPTION
The McMartin Model AMR-1 is a low cost , high perfor-
mance,
single channel AM broadcast receiver for use· as
a
reliable off-air source for house monitoring systems.
It is also intended as a companion AM receiver unit for
use with the McMartin Model EBS-2 EBS Decoder.
The AMR-1 contains a monolithic silicon integrated cir -
cuit from which the RF amplifier , IF amplifier, mixer,
oscillator, and AGC detector are constructed.
It operates on the superheterodyne principle with a 455
kHz
IF frequency A cascade IF amplifier with controlled
output impedance and negligible Miller-effect, eliminates
regeneration and selectivity skewing . A discrete diode
2/76
detector and audio amplifier are also provided fr om which
both 600
ohm balanced output at a O dBm level , as we ll
as unbalanced audio at a no minal 1.0 volt level are
brought out to
rear chassis screw t erminals . The latter
serves as audio dr ive for the EBS -2 monitor. The AMR -1
circu i try also includes a carrier off relay closure to ac-
tivate external alarm devices in th e event the co nt rol sy s-
tem becomes inoperati ve .
The AMR-1 is a co mpletely self-<:ontained, rack mo unt
unit occupying 1 3/4- of vertical space. An illum inated
front panel power switch is also provided"
Ill INSTALLATION
Upon receipt of the AMR-1, remove it from the shipping
carton and inspect it carefully for any damage caused in
trans
it.
If any damage is found, notify the shipping agency and
advise McMartin Industries of such action.
Remove the top cover of the AMR~1 and inspect al l inter•
nal circu i try for damage .
The AMR~1 should be mounted in a temperature environ-
ment of less than
so<>c .
Connect the antenna to the antenna BNC connector lo-
cated on the rear
of the chassis.
NOTE : In high signal strength areas only a short piece
of
wire will provide adequate input signal level.
Where low signal field strengths are involved a
more
elaborate antenna will be required.
If the 600 ohm balanced output termination is to be em -
ployed
for house monitoring purposes, the connection
should be made
using a twisted, shielded pair.
If the EBS-2, Emergency Broadcast Decoder, is to be
used, the unbalanced audio output terminations must be
connected to the appropriate locations on the rear chassis
of the EBS-2.
Connect the power cord to a 117 Vac source and turn the
power
switch on . The AMR-1 should now be operational.
IV CIRCUIT DESCRIPTION
The AMR-1 is a complement of four subsystems; an RF
receiver section, a diode detector, an audio amplifier,
and the carrier fai l relay circuit .
The RF receiver contains a CA3123E integrated circuit
and a discrete IF amplifier.
The antenna input is coupled through capacitor C1 to the
input tank composed of the primary of T1 and C2 wh ich
is tuned to the input frequency. The secondary of T1 is
connected
to the RF amplifier portion of IC-1 at pin 12.
The output of the RF amplifier feeds the RF amplifier
tuning section, composed of L1 , C3, and CS. This pro-
vides additional input selectivity.
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MCMartin.
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T_he amplified RF is then fed to pin 1 of IC-1 which is
the mixer input. The parallel tuned circuit (L2, C7, and
CS)
establishes internal oscillator frequency, which when
mixed
with the input signal frequency, produces a 455
kHz
IF frequency at the mixer output (pin 14 of IC1 ). C7
and
CS insure stable operation of the oscillator within
ambient temperature variations.
T2 provides selectivity prior to IF amplification. The IF
amplifier input appears on pin 7 of IC-1. The output (pin
6) is capacitive coupled to pin 5, the AGC drive input,
and
also connected to the tap of T3. T3 provides addi-
tional post IF selectivity and through C18 drives the
base
of 01. 01 is a common emitter gain stage which in-
creases the IF signal to a level sufficient to drive the
diode detector. 02 is an emitter fol lower which prevents
loading
of 01 by the detector. Diode D1 serves as the AM
detector. It is followed by a low pass filter and an audio
amplifier stage 04. 05 is connected as an emitter follow-
er.
The emitter of 05 is capacitive coupled to the unbal.-
anced 600
ohm output and also to the primary of T5. The
secondary of T5 is connected to the balanced 600 ohm
o- utput. termination. D2 generates a negative de voltage
at the base of 03 proportional to the carrier level. 03
will be biased in the •ott• condition as long as carrier is
present.
When the carrier is removed, 03 wil I be switched
"on•, energizing the c• oil of carrier fail relay, K1.
The discrete circuits in the AMR-1 are powered from a
-+22 volt de source, produced by a full wave rectifier and
an RC
filter. IC-1 operates from a +13 volt de supply,
regulated by Z1, and derived from the,+22 volt de supply.
V TROUBLE SHOOTING PROCEDURE
The AMR-1 has been aligned at the factory to conform to
the published specifications.All tuned circuits have been
adjusted to provide maximum band-width and high
select-
ivity. A perfect field alignment cannot be accomplished
without proper test equipment, therefore, if this is de-
sired it is recommended that the unit be returned to the
factory.
However, the AMR-1 can be aligned in the field, to pro-
vide satisfactory operation, with the following proced-
ures:
Connect a volt-ohmeter to test point "N' located on
the printed circuit board and adjust the meter for an
"on-scale" positive voltage reading. Adjust L2 for a
minimum
positive voltage at test point "A". If a dip
cannot be noticed on the meter when the slug of L2 is
tuned, the field strength at the antenna input may be
too low. Tune T1 and L1, in that order, for the same
condition at test point "A" .Alternately, tune T2 and
T3 for the minimum voltage at test point "A". Repeat
the tuning of
L2, T1, and L1 for the same test condi-
tion.
The AMR-1 should now be tuned to respond to the input
signal frequency.
NOTE: This tuning procedure will result in maximum
selectivity, therefore, the 6 dB bandwidth speci-
fication cannot be guaranteed if this tuning pro-
cedure is used. Greater audio bandwidth can
be
obtained by slightly detuning T1 and L1.
In the event of malfunction, check the following symp-
toms and procedures:
A. Carrier fail relay will not operate
1. Check power supply voltage
2. Short the collector of 03 to ground and determine
if relay is functional
3. Check 03 and D2
4. Check ~.,tenna input RF level. It should be a min-
imum of 100
microvolts.
B. No audio output
1. Connect
VOM to test point "A" and remove an-
tenna. The voltage reading on the meter should
rise. This indicates that IC-1 is working properly.
a. Trace the signal through 01, 02, D1, 04, and 05
untiI trouble is located.
3. Check power supply
4. Perform aIignment procedure
C. Audio output distorted
1 • Check power supply voltage
2. Insure that antenna input is not overloaded, by re-
dueing antenna length.
3. Perform aIignment procedure
D. Noise in audio output
1 • Cheek a
11 grounds
2. Antenna input signal level Is probably too low, In-
crease antenna length.
E .All other problems should be referred to the factory
by contacting the McMartin's Customer Service
Manager.
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MCMartin.
8/74
VI PARTS LIST
The majority of the components used In the AMR-1 are of standard values and tolerances and are gener-
ally available from local electronics parts distributors. The following list includes those items of crit-
ical value and tolerance or components manufactured by McMartin Industries.
SYMBOL
T4
SW-1
F1
SYMBOL
T1,2,3
T5
L1, 2
K1
IC-1
01,3,4
02,5
D1, 2
D3,4
21
ca
GENERAL PARTS
P/N
900037
480029
280033
PRINTED CIRCUIT BOARD
P/N
940014
910029
930098
470029
230048
201056
201049
220006
210008
220007
DESCRIPTION
Power transformer
Power switch assembly
1
/16 amp fuse
DESCRIPTION
Transformer
Output transformer
Inductor
Carrier fai I relay
CA3123E
2N3569
SE4002
IN87 diode
IN4006 {l lode
13
voltzener
Selected in production
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MC Martin.
WARRANTY
McMartin products are warranted to be free from defects in materiaIs
and workmanship
for a period of one year after shipping date, when
subjected to normal usage and service. All warranties are void if
(a) equipment has been altered or repaired by others without McMar-
tin's specific prior authorization; or (b) equipment is operated
under environmentaI
conditions or circumstances other than those
specifically described in McMartin literature or instruction man-
uals.
Upon notification within the applicable warranty period, McMartin
agrees
without charge, to repair, replace, or supply replacement
parts for any properly maintained equipment or parts that are de-
fective as to design, materials, or workmanship and that are re-
turned in accordance with McMartin's instructions to the Buyer.
At McMartin's sole discretion, the Buyer may be re:iuested to re-
turn the defective part or equipment to McMartin, FOB Omaha,
Nebraska. Parts or equipment may be returned only with McMar-
tin's prior authorization and must be identified by a return auth-
orization number issued by McMartin's Customer Service Depart-
ment. Al I merchandise so returned must be sent transportation
prepaid, at Buyer's risk. Full details of the failure or malfunction
should be included so as to expedite repair or replacement. Re-
pair parts or repaired or replaced equipment wi II be returned to
the Buyer, FOB factory.

STEAM POWERED RADIO.COM
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