30 December 2000
Source: Hardcopy from the National Security Agency in response to an
appeal of an earlier FOIA
request for TEMPEST-related documents. This is one of three full and five
partial documents received under the appeal. See NSA letter and list of
For comprehensive TEMPEST information see:
[9 pages; all marked:
FOR OFFICIAL USE ONLY]
SPECIFICATION NSA NO. 94-106
SPECIFICATION NSA NO. 94-106
date: 24 October 1994
SPECIFICATION NSA NO. 65-6
30 October 1964
NATIONAL SECURITY AGENCY
1. SCOPE. This specification provides the general requirements for
the installation and performance of shielded enclosures to attenuate
electromagnetic radiation. This specification shall be reviewed at least
every three years. The requirements of this specification apply to all associated
and auxiliary facilities furnished as part of a shielded enclosure.
2. APPLICABLE DOCUMENTS. The following document in effect on the date
of invitation forbid forms apart of this specification to the extent specified
Military MIL-STD-220A Method of Insertion-Loss Measurement
3.1 Performance. The shielded enclosure shall meet the requirements for
electromagnetic attenuation as specified in Figure 1.
3.2 Design. Maximizing electromagnetic attenuation shall be stressed throughout
the shielded enclosure's design, construction and erection. Where demountable
construction is required, the enclosure shall be constructed to allow for
easy disassembly and reassembly with a minimum of effort and without degrading
3.3 Reliability. The shielded enclosure will be subject to varying floor
loads, repeated use of access doors, and continuous use of the HVAC and
electrical filters. When maintained in accordance with the manufacturers
preventative and routine maintenance instruction, it shall retain the specified
attenuation for a minimum of five years without retightening of bolts (if
used), seams or other major maintenance.
3.4 Material. All materials, parts, mechanical and electrical assemblies
shall be new, unused, undamaged, of quality consistent with the proposed
use and specified performance, and in accordance with referenced documents.
All material shall be free from defects and imperfections that might affect
the serviceability and appearance of the finished product.
3.5 Warranty. The contractor shall stipulate in writing that the shielded
enclosure furnished under the requirements of this specification will meet
and maintain the appropriate attenuation requirements f or not less than
five years after initial installation. The contractor shall be responsible
for the repair or replacement of any part which reduces the attenuation below
the required level.
3.6 Publications and Drawings. A minimum of two sets of publications,
instructions and drawings for the enclosure shall be provided in a bound,
durable binder detailing at least the following:
a. Assembly and disassembly of the shielded enclosure including individual
diagrams of each stage of assembly and disassembly, showing framing, enclosure
panels and all internal finishing materials and accessories.
b. Assembly and installation of the HVAC system, ducts and all penetrations.
(see 6.1 (e)).
c. Electrical wiring, including electrical panel layout (if required),
installation and wiring of electrical filters, isolators, and grounding.
d. Preventive and routine maintenance including instructions, schedules,
and appropriate replacement parts list by item identification and part number.
e. Load limits for all surfaces of the shielded enclosure.
f. Each ancillary device furnished under the contract.
Detail shall include a bill of materials that clearly indicates and identifies
all component parts by manufacturer's name, part number, and description.
3.7 Enclosure Structure
3.7.1 Size. The dimensions of the enclosure will be as specified in the contract.
3.7.2 Shielding Material. The selection of shielding material will be at
the option of the contractor unless specified in the contract. It must be
noncorrosive material. Contact between dissimilar metals that causes corrosion
must be avoided.
3.7.3 Joints/Seams. If bolted construction is used, then seams must be bolted
from the inside only. Joints of double-walled enclosures may have outside
bolted joints on outside walls, provided there is sufficient space in the
parent room adjacent to the walls to allow retightening of the outside bolts.
3.7.4 Special Tools. The contractor shall supply any tools required to install
3.7.5 Workmanship. The enclosure and accessories shall be free from defects
that may affect appearance or serviceability and shall conform to the
requirements of this specification.
3.7.6 Surface Requirement. Wall, floor and ceiling covering shall be as specified
in the contract. A suitable system to support cables, pipes, special fixtures,
etc. around the inner or outer surfaces of the enclosure shall be as specified
in the contract. The floor and floor covering shall be capable of withstanding
the floor loading requirements specified in the contract. Attenuation
characteristics shall not be adversely affected by noncorrosive
liquids-accumulating on top the enclosure, or from noncorrosive spills within
the enclosure, or from the presence of water or moisture on the parent room
3.8 Additional Requirements.
3.8.1 Access Doors. Door hinges shall support the door's weight without sagging.
Doors shall have closing and latching mechanisms to provide positive closure,
so that the entire door area including juncture between door and frame at
all points meets the attenuation requirements.
3.8.2 HVAC. HVAC ducts shall not restrict the flow of air required for proper
operation of the air conditioner. It is the contractor's responsibility to
ensure that HVAC installation does not degrade the attenuation of the enclosure.
3.8.3 Power and Line Isolation. Isolation devices shall be provided for each
*line penetrating the shielded enclosure. The devices are to be mounted so
as not to degrade the enclosure's attenuation. The power isolation system
shall provide a minimum of 100 dB insertion loss from 1 KHz to 10 GHz.
3.8.4 Grounding. A single ground lug connected to the shield surface shall
be provided. This lug shall be connected to the nearest building structural
member. This connection shall have DC resistance of 1 ohm or less with the
ground connection in place, and 10 megaohms or greater with the ground connection
4. QUALITY ASSURANCE PROVISIONS
4.1 Contractor's Responsibility. Unless otherwise specified herein, the
contractor is responsible for the performance of all inspection requirements
prior to submission for contracting officer's representative inspection and
acceptance. Except as otherwise specified, the contractor may utilize his
own facilities or any commercial laboratory acceptable to the Government.
Inspection records for examinations and tests shall be complete and available
to the Government. The Government reserves the right to perform any of the
inspections set forth in this specification, where such inspections are deemed
necessary to assure supplies and services conf orm to prescribed requirements.
4.2 Inspections and Tests.
4.2.1 In Process Inspections. During construction, the contracting officer's
representative reserves the right to conduct recurrent inspections at the
contractor's plant. It shall be the responsibility of the contractor to extend
full cooperation to the contracting officer's representative during such
inspections, and to advise the representative of any deviations from applicable
4.2.2 Acceptance Inspection. Acceptance inspection shall be conducted under
the supervision of a contracting officer's representative. All necessary
personnel, facilities and test equipmentfor performing tests and inspection
required by this specification shall be furnished by the contractor. Test
equipment shall possess the necessary calibration, frequency range, sensitivity,
power output, accuracy and quality for the required tests.
188.8.131.52 Contractor Installation. The contractor shall perform the acceptance
tests of paragraph 4.3 at the site of installation.
184.108.40.206 Other Installations. On contracts not requiring on-site erection,
the contractor shall perform the acceptance tests of paragraph 4.3 at its
plant on a sample shielded enclosure that is similar to the enclosure(s)
to be delivered in all characteristics which affect attenuation properties.
4.3 Acceptance Tests. Acceptance tests shall be performed in accordance with
the procedures detailed in this section for electromagnetic attenuation.
A test plan, detailing test locations, shall be submitted and approved prior
to performance of the tests.
4.3.1 Electromagnetic Attenuation Tests. (Figure 1)
Continuous wave (CW) source, 1 KHz to 10 GHz.
Transmitting and receiving magnetic field antenna set covering 1 KHz to 1
Transmitting and receiving electric field and plane wave antenna set covering
1 KHz to 10 GHz.
Receivers or spectrum analyzers covering 1 KHz to 10 GHz with adequate dynamic
range to measure the attenuation required in Figure 1.
220.127.116.11 Magnetic/Electric/Plane Wave Test. The magnetic and electric f ield
attenuation tests shall be performed with the antennas located directly opposite
each other and separated by a distance of 61 centimeters (24 inches) plus
the wall thickness (See Figure 2.a.) Magnetic field attenuation shall be
measured at 1 kHz, 10 kHz, 100 kHz, and 1 MHz. Electric field attenuation
shall be measured at 1 kHz, 10 kHz, 100 kHz, 1 Mhz, and 10 MHz. The plane
wave attenuation test shall be performed with the transmitting antenna placed
at least 6 meters away from the enclosure surface (where practical) and the
receiving antenna set no closer than 5.1 centimeters (2 inches) from the
wall (See Figure 2.b.) Plane wave attenuation shall be measured at 100 MHz,
400 MHz, 1 GHz, and 10 GHz. Measurements, for all tests, shall be taken with
the antennas oriented for maximum received signal strength. Attenuation tests
shall be performed around the entire door frame, air ducts, filters and through
any accessible joint or penetration. In addition, the magnitude and location
of the maximum signal level emanating from the enclosure shall be determined
by testing at least f our locations. The selection of testing locations should
include not only walls, but also the floor and ceiling. Tests shall be performed,
at a minimum, on every 180 square feet of surfade area. All test locations
and results shall be documented. The lowest attenuation level performed from
all the tests shall be recorded as the attenuation of the enclosure. If possible,
all tests should be performed with the receiver outside and the transmitter
inside the enclosure. The Government reserves the right to require tests
at specific frequencies and locations to determine compliance of the enclosure
with this specification.
4.3.2 Filter Insertion Loss. All installed isolation devices shall be tested
for their insertion loss or attenuation. Power filters shall be tested for
insertion loss in accordance with MIL-STD-220A. All filters shall be installed
on the enclosure for the attenuation tests. All power filters shall also
be tested for voltage drop (not to exceed 2%) under one half and full rated
current. They must operate under full load for ten hours before testing.
The increase in temperature of the case during this period must not exceed
25o Centigrade (77o Fahrenheit) above the ambient
temperature of the room.
5. PREPARATION FOR DELIVERY
5.1 Preservation, Packaging and Packing. All enclosure hardware shall be
packaged in a secure manner, sealed appropriately and shipped using approved
security measures to prevent tampering.
5.2 Packing List. A complete packing list shall be provided, showing exactly
where every part of the enclosure is packed. This applies to room size enclosures
vice whole structure shielding. The packing list when applicable shall include
the crate number for each part and its location within the crate.
6.1 OrderingData. Procurement documents shall specify the following:
a. Title, number and date of this specification and any amendment thereto.
b. Whether the enclosure(s) shall be installed by the contractor, or whether
the contractor shall perform acceptance tests on a sample enclosure.
c. Area dimensions of the parent room and available electric power at the
d. Environmental conditions of the parent room and heat dissipation load
(equipment, lights and personnel) within the enclosure(s).
e. Whether the contractor shall furnish an air conditioning unit; if so,
specify temperature and humidity requirements.
f. Size(s) of enclosure(s).
g. Number, size, location and opening direction of access door(s).
h. Type of floor, floor covering and floor loading requirements.
i. Type of wall and ceiling covering.
j. Size and location of service entrance panels complete with arrangement
drawing of connectors.
k. Type, size and quantity of signal and power line c6nnectors for service
l. Quantity, voltage and current requirements of power line filters; requirements
for signal line filters (or isolators), including: type, frequency, insertion
loss, voltages, currents, power, impedance, mounting requirements, etc.
m. Lighting and convenience receptacle requirements.
n. Grounding facilities characteristics.
o. Preparation for delivery.
p. Exception to inside bolted joint if applicable.
q. Security clearance of construction and test personnel.
r. Whether the contractor shall furnish combination lock(s) for access cloor(s),
and the approved type, when appropriate.
6.2 Disclosure of Information. The contractor shall not divulge any information
as to the requirements of this specification to any person not specifically
authorized in writing to receive such information by the:
Maryland Procurement Office
9800 Savage Road
Ft. George G. Meade, MD 20755-6000
6.3 When requesting copies, stipulate the title, number of the specification
and the purpose for which required.
6.4 Changes/Clarifications. Recommended corrections, additions, deletions
or clarifications to this specification should be addressed to:
Maryland Procurement Office
9800 Savage Road
Ft. George G. Meade, MD 20755-6000
NOTICE: When Government drawings, manuals, specifications or other data are
used for any purpose other than in connection with a Government procurement
operation, the United States Government thereby incurs no responsibility
or any obligation whatsoever. The fact that the Government may have formulated,
furnished, or in any way supplied the said drawings, specifications, or other
data is not to be regarded by implication or otherwise as in any manner licensing
the holder or any other person or corporation, or conveying any rights or
permission to manufacture, use or sell any patented invention that may in
any way be related thereto.
[Enlarged Figure 1.]
[Enlarged Figure 2.a.]
[Enlarged Figure 2.b.]
Transcription and HTML by Cryptome.
NSA also provided another document entitled "Specification NSA No. 89-02,
TBD, National Security Agency Specification for Shielded Enclosures." [No
date]. It is marked: "Superceding Specification NSA No. 65-6, 30 October
1964," and "Specification NSA No. 73-2A, 15 November 1972." The text is almost
identical to the document above which appears to have superceded it, thus
it has not been transcribed.