Subject: MSC2001
From: <Saved by Microsoft Internet Explorer 5>
Date: Wed, 20 Oct 2004 13:15:16 +0200

MSC2001 Voice Encryption Unit (VEU)
©
Brooke Clarke, N6GCE

Background

Construction

Connector
Pinouts
DC Power
Testing
Links

Background

This is another voice security device used with
radios like the PRC-77.  This
box has an identical function as the KYV-2, KY-38 or KY-57 Transmission
Encryption Devices, although it uses a different algorithm.

In order to
use it two things need to be accomplished:
(1) a key needs to be loaded into
one or more of the 8 slots.

There are a number of key loaders for the U.S. crypto boxes
including the CV-4228 PC to
SINCGARS fill cable.  This fill cable uses the RTS and DTR lines to
generate the Clock and Data streams (NOT the transmit data line which has no
clock).  This method is much simpler in terms of hardware, but more
complex in terms of software than building a custom key loader for the
MSC-2001.

A very simple cable could be made by wiring the RS-232
outputs from RTS and DTR directly to the clock and data pins on the
MSC-2001.  No active parts are required and the same software that drives
the CV-4228
could be used.

(2) an interface needs to be used between the
MSC-2001 and the radio.

Vehicle
The KY-57 is used with the J-3513 Junction
Box that interconnects the KY-57, radio, DC power supply, and Vehicle
Inter Communication (VIC) equipment or
wire line adapters.  The J-3513 (or the smaller J-3514) might also work
as the interface between the MSC-2001 and the rest of the system?

Manpack
It may be that just a cable could be used between the MSC-2001
and a PRC-77, like the CX-12991/U between the KY-57 and PRC-77.  The pin
assignments on the MSC-2001 strongly suggest this is the case. Although the
cable is NOT a 1 to 1, it's close.

Construction

This is the model S42043-E9-B104 with a code selection
switch.

There are two main printed circuit boards using
through hole components.  The boareds appear to be double sided with the
bottom traces generally going left to right and the top traces going up to
down.  A 40 pin IC (probably a micro processor) is in a socket formed using
40 individual sockets.  Nearby are what appear to be a couple of ROM
chips.

There's also 5 daughter printed circuit boards which use
surface mount technology and have been painted red.  Four of these red
boards have 3 or 4 each ICs with 6 leads, most likely op amps.  None of
them have any higher pin count chips so they most likley are analog
processing.

Another larger daughter board has a couple of pot core type
inductors/transformers and has the feel of a switching mode power supply.
It has a 74S40 Switching
Mode Power Supply controler IC rated at 1.5 Amps and 100 kHz.

There's
a couple of green wire wrap wires soldered to the bottom of one of the printed
circuit boards indicating a "fix" was needed.

The 3.4 Volt "AA" size
battery in this unused unit was completly dead (0.0 Volts).

There's a lot
of 14 pin 14xxx series CMOS ICs: MC14001 Quad 2-Input NOR gate, MC14013 Dual
Type D Flip-Flop, MC14015 Dual 4-Bit Shift Register, MC14024 7-Stage Ripple
Counter, MC14025 Triple 3-Input NOR Gate, MC14035 4-Bit Parallel-In/Parallel-Out
Shift Register, MC14066 Quad Analog Switch, MC14070 Quad XOR and NOR Gates,
MC14519 4-Bit AND/OR Selector or Quad XOR, MC14572 Hex Gate, and some other
chips near the 40 pin IC.

There are two connectors, both of which are the
same as the POWER connector on a PRC-77 radio.  One is labeled REMOTE and
may be used in an aircraft installation to control the MODE selection of which
code to use.  The other connector is marked TX/RX and is the interface to
the PRC-77 or other wide band radio.  The REMOTE connector is also used for
loading up to 8 keys.

The Tx/Rx connector has the following pins
connected to the same letter pin on the REMOTE connector: A, B, C, D, E, F,
J.  On my unit with the front panel switch, I see no way the REMOTE
connector can control the channel selection.  Maybe it does on the other
version.  The REMOTE does have the key load connections which are not on
the Ts/Rx connector.

The MODE switch has 8 channel positions for
different keys plus positions for CLEAR speech and CODE ERASE.  The switch
has no mechanical stops and can be turned completly in a circle.  There's a
thin plastic disk on the switch shaft under the knob that has a pointer sticking
out past the diameter of the knob.  If the switch is turned either
clockwise or counterclockwise to the CODE ERASE position the thin plastic disk
breaks into two pieces.  If this happens you can use acrilic cement
(solvent) to fix the disk.

The 10 position Grayhill
- Series 71
(marked on back 81073) switch has only 5 wires connecting it to the rest of
the MSC-2001.  This is a 1, 2, 4, 8 binary switch.  The black wire is
ground, Violet is 1, Orange is 2, Yellow is 4, and Green is 8.  Decimal
position 0 is labeled 1, position 7 is labeled 8, position 8 is labeled CLEAR
and position 9 is labeled CODE ERASE.

Connectors

There are 2 connectors on the MSC2001 one labeled
Tx/Tx used for the radio interface and one labeled Remote that's used for either
key loading or for connection to other equipment, like the AM-2060 or the MK-456 retransmission
kit.

This table is my best guess as to what the pinout is.  You can
see the MSC2001 was designed with the PRC-77 in mind.

Pin

H-250

PRC-77

MSC2001
Tx/Rx

Linked

MSC2001
Remote

A

Gnd

Gnd

Gnd

=

Gnd

B

spkr

Aud out

Aud out

=

Aud out

C

PTT

PTT

PTT

=

PTT

D

Mike

Aud in

Aud in

=

Aud in

E

-

+15 in

+15 in

=

+15 in

F

-

Batt +15

Batt +15

=

Batt +15

H

-

nc

PTT?

=

key CTS in

J

-

Mike gnd

Mike gnd

=

Mike gnd

K

-

retrans PTT

nc

x

-9 out

L

-

tone dsbl in

tone dsbl in

x

key clock in

M

-

nc

Aud out

x

key RTS out

N

-

sw +10 out

+12 in

Note 1

+12 in

P

-

Rx-X-out

X out

x

key data in

R

-

Tx-X-in

X in

x

key RTS
in

Note 1 - Both "N" pins are DC inputs that are
joined by diodes so either one will power the MSC2001, yet the DC can not be fed
from either.

DC Power

Main

Main "12 Volt"
power is supplied through either of the connectors.  Power on-off is
handled by external wiring.  With my home made Tx/Rx cable power is
supplied to the MSC-2001 when the PRC-77 is switched on.

PRC-77 pin "N"
is switched 12 Volt power.  There is no direct connection between the
MSC-2001 REMOTE pin "N" an the Tx/Rx pin "N".  But they both feed through a
diode "OR' to the power MSC-2001 supply so either one will power the
MSC-2001.

Pins "E" (12 Volts into PRC-77) and "F" 12 Volts from
battery are straight through from Tx/Rx to REMOTE, allowing power for the PRC-77
to be feed through the MSC-2001, like when the MSC-2001 is connected in series
from the SET POWER jack on the AM-2060A to the MSC-2001 REMOTE connector and
then from the MSC-2001 Rx/Tx connector to the PRC-77 POWER
connector.

Hold Up Battery

The Hold Up Battery (HUB) is the same 3+ Volt
"AA" size as used in the PLGR.

Testing

7 May 2004 - Connected home
made cable between the MSC-2001 and a PRC-77 with a 257477BA Battery
Adapter to power the PRC-77 and MSC-2001.  With the mode switch on any
of the 8 key slots the H-250 handset connected to the PRC-77 sounds like a
telephone busy tone, indicating no key loaded.  With the MODE switch set to
CLEAR the handset hears noise on receive and on transmit a carrier is sent, but
no modulation sometimes and others a squealing tone is transmitted and heard in
the handset. Done with no HUB battery installed.  The cable includes a
jumper to disable the 150 Hz tone, which is the common thing done with voice
security devices.

Links

Jery Proc's Crypto Machines
- MSC-2001

Coby's Place - Tips and
Troubleshooting -

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