Kantronics MT1200 User manual

MT1200 and MT1200G
Users Guide: Introduction,
Getting Started,
Modes of Operation,
Command Reference, and
Hardware Specifications
Kantronics
3115 W. 6th St., Suite A
Lawrence, Kansas 66049
Orders / Inquiries [phone]
FAX [phone]
e-mail: [e-mail]
website: www.kantronics.com
Service / Technical Support [phone] (8 AM to 12 noon and 1 PM to 5 PM Central Time, M-F)
FAX [phone]
e-mail: [email protected]

REVISIONS
Revision Date Description
REV- 2006-12-29 Release version
REV-B 2007-03-06 Corrections, updates, additions
i

The MT1200 is a Kantronics hardware and software design incorporating the AX.25 Level 2 Version 2 Packet
protocol as adopted by the American Radio Relay League. It is designed to be used as a GPS beacon from a
mobile environment.
We have attempted to make this manual technically and typographically correct as of the date of the current
printing. Production changes to the TNC may add errata or addendum sheets. We solicit your comments
and/or suggested corrections.
Please send your comments and/or suggestions to:
Kantronics Co., Inc.
3115 W 6th St., Suite A
Lawrence, KS 66049.
The MT1200 is manufactured in the U.S.A.
© Copyright 2006 by Kantronics Co., Inc. All Rights Reserved.
Contents of this publication or the firmware within the MT1200 may not be reproduced in any form without the
written permission of the copyright owner.
MT1200 is a registered trademark of Kantronics Co., Inc.
KPC-3 Plus is a registered trademark of Kantronics Co., Inc.
KPC-9612 Plus is a registered trademark of Kantronics Co., Inc.
KAM ’98 and KAM XL are registered trademarks of Kantronics Co., Inc.
APRS is a registered trademark of Bob Bruninga, WB4APR.
HyperTerminal is a registered trademark of Microsoft.
ii

Kantronics Warranty Registration
Please take the time to fill out the warranty registration form (or a copy of the form) and mail it to Kantronics,
including a copy of your sales receipt, to register your purchase. Kantronics must receive warranty registration
within 60 days of purchase of the Kantronics MT1200 to be valid. Both must be on file at Kantronics in order
for you to receive warranty service. Refer to the warranty policy in this manual for further information.
Warranty Registration form and copy of sales receipt may be e-mailed to [email protected].
Mail form and sales receipt to:
KANTRONICS
3115 W. 6th St., SUITE A
LAWRENCE, KS 66049
Warranty Registration
Last Name: __________________________
First Name: __________________________ Call Sign: ___________________________
Mailing Address: _________________________________________________________________________
City: _______________________________ Telephone: ____________________________________
State: ______________________ E-Mail: _______________________________________
Zip/Postal Code: ______________________
Country: ____________________________
Product: MT1200(G) Serial #: ________________________________________
Date of Purchase: _____________________ Dealer: _________________________________________
Note: The serial number of the unit is displayed to the terminal in the sign-on message when the MT1200 is
powered on.
iii

IMPORTANT:
READ THIS PAGE BEFORE YOU INSTALL YOUR NEW KANTRONICS PRODUCT
This product contains SOFTWARE in FLASH memory and/or diskette and/or CD, which
is protected by both United States copyright law and international treaty provisions.
If you install or use this product, you will be deemed to be bound by the terms of the
SOFTWARE license shown below. If you do not wish to be bound by such license,
return such product and all associated documentation unused to your supplier for
refund of the amount you paid.
License Agreement
1. License. In consideration of payment of the License Fee, which is included in the
price of the product, the Licensee (you) is granted by the Licensor (Kantronics
Company, Inc. - Kantronics) a non-exclusive right to use the SOFTWARE and
associated documentation. No ownership rights to the SOFTWARE or its
Documentation are transferred from Kantronics to you.
2. Term. This License Agreement is effective until terminated. You may terminate this
Agreement by destroying the PROM or diskette or CD and Documentation. You may
not rent or lease the SOFTWARE, but you may transfer the SOFTWARE and
accompanying written materials on a permanent basis provided you retain no copies
and the recipient agrees to the terms of this Agreement. Kantronics may terminate
this Agreement without notice if you violate any terms or conditions of the
Agreement. In the event of termination of the Agreement, provisions relating to
Kantronics’ disclaimers of warranties, limitation of liability, remedies, or damages
and Kantronics’ proprietary rights shall survive.
3. Object Code. The SOFTWARE is delivered in object code only. You shall not
reverse compile or otherwise reverse engineer the SOFTWARE.
4. Limited Warranty. This product is covered by the standard Kantronics Co., Inc.
Limited Warranty, which is enclosed.
5. General. This License Agreement constitutes the complete Agreement between you
and Kantronics.
The SOFTWARE and/or Documentation may not be exported or re-exported in violation
of any export laws or regulations of the United States of America or any other applicable
jurisdiction.
iv

This Agreement shall be governed by and interpreted under the laws of the State of
Kansas, United States of America.
Use, duplication, or disclosure by the Government of the United States is subject to
restrictions as set forth in subparagraph (c)(1)(ii) of the Rights in Technical Data and
Computer SOFTWARE clause of DFARS 252.227-7013.
Kantronics may in its sole discretion, provide you with upgrades of the SOFTWARE
and/or Documentation if you have provided Kantronics your completed Warranty
registration with a copy of your receipt showing the amount you paid.
LICENSEE ACKNOWLEDGES HAVING READ AND UNDERSTOOD THIS
AGREEMENT AND AGREES TO BE BOUND BY ITS TERMS. LICENSEE FURTHER
AGREES THAT THIS AGREEMENT IS THE COMPLETE AND EXCLUSIVE
STATEMENT OF THE AGREEMENT BETWEEN LICENSEE AND LICENSOR AND
SUPERSEDES ANY PROPOSAL OR PRIOR AGREEMENT, ORAL OR WRITTEN,
AND ANY OTHER COMMUNICATIONS RELATING TO THE SUBJECT MATTER OF
THIS AGREEMENT.
Any questions concerning this Agreement or any other matter relating to Kantronics
Company, Inc. products or business practices may be directed to:
Customer Service Department
Kantronics Company, Inc.
3115 W. 6th St., Suite A
Lawrence, KS 66049
v

TABLE OF CONTENTS
MT1200 and MT1200G...............................................................................................................................................................................1
REVISIONS.................................................................................................................................................................................................i
Kantronics Warranty Registration..............................................................................................................................................................iii
IMPORTANT:............................................................................................................................................................................................iv
License Agreement.....................................................................................................................................................................................iv
TABLE OF CONTENTS.............................................................................................................................................................................1
LIMITED WARRANTY.............................................................................................................................................................................4
Return/Repair Procedures........................................................................................................................................................................7
International Returns............................................................................................................................................................................9
Radio Frequency Interference Statement...................................................................................................................................................11
RFI Suppression.....................................................................................................................................................................................12
Welcome................................................................................................................................................................................................15
Package Contents...................................................................................................................................................................................15
Additional Parts for Your Packet Radio Station....................................................................................................................................16
Overview of This “User’s Guide” Manual............................................................................................................................................16
Uses of Your MT1200...........................................................................................................................................................................18
Our Assumptions about You..................................................................................................................................................................18
Installing Your MT1200(G).......................................................................................................................................................................19
The MT1200......................................................................................................................................................................................19
Connect Your MT1200 to a Power Source............................................................................................................................................20
Connect your MT1200 to Your Computer.............................................................................................................................................20
Installing the RS232 Cable................................................................................................................................................................23
Cabling an external GPS receiver to an MT1200 .............................................................................................................................24
Alternate GPS Input...........................................................................................................................................................................25
Configure Your MT1200.......................................................................................................................................................................26
HyperTerminal...................................................................................................................................................................................26
AUTOBAUD.....................................................................................................................................................................................27
Setting Basic Communication Parameters.........................................................................................................................................28
Documentation Conventions..................................................................................................................................................................28
Trouble-Shooting Difficulties in Communicating.............................................................................................................................29
Connect the MT1200 to Your Transceiver............................................................................................................................................31
Parts needed for assembling a TNC to Radio cable...........................................................................................................................31
Preparing the Transceiver Cable Assembly.......................................................................................................................................31
Connecting Your Transceiver Cable Assembly.................................................................................................................................39
Adjusting the Receive Volume of Your Transceiver.........................................................................................................................40
Transmit level adjustment..................................................................................................................................................................40
Getting Started...........................................................................................................................................................................................42
The Front Panel of the MT1200.............................................................................................................................................................43
Beginning a Session...............................................................................................................................................................................44
Giving Commands and Transmitting Data............................................................................................................................................44
Check Your MT1200’ Version Number and ID................................................................................................................................45
Get Help.............................................................................................................................................................................................45
View Current Values of Parameters..................................................................................................................................................46
Change the Value of a Parameter.......................................................................................................................................................46
Monitor Communications From Nearby Stations..................................................................................................................................47
Communicate Directly with a Nearby Station.......................................................................................................................................47
Modes of Operation...................................................................................................................................................................................49
Packet Mode...........................................................................................................................................................................................49
Protocol for Amateur Packet Radio: AX.25......................................................................................................................................49
1

Command Mode.................................................................................................................................................................................49
Connected vs. Unproto.......................................................................................................................................................................49
Monitoring and Calling CQ...............................................................................................................................................................50
Flow Control......................................................................................................................................................................................50
Convers Mode vs. Transparent Mode................................................................................................................................................52
Exiting Transparent Mode.................................................................................................................................................................52
Linesub mode.........................................................................................................................................................................................54
LINESUB Protocol Description .......................................................................................................................................................54
TUP mode (Transparent Unproto Packet) ...........................................................................................................................................55
TUP Mode Description .....................................................................................................................................................................55
Poll Mode ..............................................................................................................................................................................................57
Poll Mode Protocol Description ........................................................................................................................................................57
Modem Mode.........................................................................................................................................................................................60
KISS Mode.........................................................................................................................................................................................61
XKISS (Extended KISS) Mode.........................................................................................................................................................62
Remote Access ......................................................................................................................................................................................63
GPS Beacon...........................................................................................................................................................................................65
Configuring the MT1200 GPS Beacon..............................................................................................................................................65
Other GPS Beacon Features...............................................................................................................................................................66
GPS Command Summary..................................................................................................................................................................68
Bibliography......................................................................................................................................................................................68
Other Modes of Operation.....................................................................................................................................................................70
Remote Sensing and Control.............................................................................................................................................................70
Command Reference..................................................................................................................................................................................72
Introduction............................................................................................................................................................................................72
Format Defining Commands..............................................................................................................................................................72
Parameter Types.................................................................................................................................................................................73
Entering Commands...........................................................................................................................................................................75
MT1200 Commands..............................................................................................................................................................................77
Appendix A: Advanced Installation.........................................................................................................................................................124
Precautions...........................................................................................................................................................................................124
Cable Wiring........................................................................................................................................................................................124
Diagram of Pin Numbers on DSUB-9 Connector............................................................................................................................124
Connecting to the Computer (Front panel DSUB-9)...........................................................................................................................124
Cable Wiring....................................................................................................................................................................................125
Software settings..............................................................................................................................................................................126
Connecting to your Radios...................................................................................................................................................................126
Radio port pin numbers and functions.............................................................................................................................................126
Interfacing Hand-Held Radios.........................................................................................................................................................127
Optional Connections to DSUB-9 Radio Port.................................................................................................................................129
Connections to the I/O jack..............................................................................................................................................................129
Appendix B: Advanced Information....................................................................................................................................................130
Assembly and Disassembly.............................................................................................................................................................130
Hard Reset/Self-Test............................................................................................................................................................................130
Bios Load.............................................................................................................................................................................................132
Calibration/Equalization......................................................................................................................................................................132
Drive level........................................................................................................................................................................................133
Equalization.....................................................................................................................................................................................133
Microprocessor Watchdog Timer........................................................................................................................................................133
A/D Sensor Inputs................................................................................................................................................................................134
MT1200 Jumpers.................................................................................................................................................................................135
Jumper Locations.............................................................................................................................................................................135
Jumper Descriptions.........................................................................................................................................................................136
Appendix C: In Case of Difficulty...........................................................................................................................................................137
MT1200 Does Not “Sign-On” to Computer........................................................................................................................................137
You Are Unable to Make a “Connect”................................................................................................................................................137
2

Cannot Transmit...................................................................................................................................................................................138
Cannot Return to Command Mode......................................................................................................................................................138
Appendix D: Additional Information.......................................................................................................................................................139
Specifications.......................................................................................................................................................................................139
Messages from the MT1200................................................................................................................................................................141
ASCII Chart.........................................................................................................................................................................................146
.............................................................................................................................................................................................................146
MT1200 Parts List...............................................................................................................................................................................147
MT1200 Parts Layout..........................................................................................................................................................................148
3

LIMITED WARRANTY
KANTRONICS CO., INC.
LIMITED WARRANTY
Effective January 1, 1997
To receive notice of future updates, new product information and prompt warranty
service, please fill in the Kantronics Warranty Registration form COMPLETELY and
return it along with a copy of proof of purchase (to establish purchase date) to
Kantronics Co., Inc., 3115 W. 6th St, Suite A, Lawrence, Kansas 66049 USA. The
Warranty Registration form and proof of purchase may be e-mailed to
[email protected].
NOTE: Return of the Warranty Registration form and proof of purchase is a pre-
condition to warranty coverage.
1. WARRANTY. Kantronics Co., Inc. (“Kantronics”) warrants to the first consumer
purchaser (“you”), for the Applicable Warranty Period (as described below), that the
Applicable Product (as described below) will be free from defects in material and
workmanship.
2. REMEDY. Kantronics agrees that, for any Applicable Product found by Kantronics to
be in violation of the warranty of Section 1 hereof within the Applicable Warranty
Period, it will, at its option, repair or replace the defective Applicable Product at no
charge to you, excluding in-bound shipping charges.
3. EXCLUSIVE REMEDY. Repair or replacement of the Applicable Product, as
provided herein, is the sole remedy available to you against Kantronics, and in no
event will Kantronics be responsible for any other liability or damages or for
incidental, special, or consequential damages, regardless of whether purported
liability is predicated upon negligence, strict tort, contract, or other products liability
theory and whether or not Kantronics is warned about the possibility of such liability
or damages. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION
OF INCIDENTAL OR CONSEQUENTIAL DAMAGES, SO THE ABOVE
LIMITATION OR EXCLUSION MAY NOT APPLY TO YOU.
4. DISCLAIMER. This Limited Warranty is in lieu of all other warranties expressed or
implied and no representative or person is authorized to assume for Kantronics any
other liability in connection with the sale of its products. KANTRONICS
SPECIFICALLY DISCLAIMS THE IMPLIED WARRANTY OF MERCHANTABILITY
AND IMPLIED WARRANTY OF FITNESS FOR A PARTICULAR PURPOSE FOR
ANY APPLICABLE PRODUCT. IF, HOWEVER, YOU ARE A CONSUMER WITHIN
THE MEANING OF 15 U.S.C. 2301(3), THE ABOVE DISCLAIMER OF IMPLIED
WARRANTIES IS EFFECTIVE ONLY FOR PERIODS OUTSIDE THE APPLICABLE
WARRANTY PERIOD. SOME STATES DO NOT ALLOW LIMITATIONS ON HOW
4

LONG AN IMPLIED WARRANTY LASTS, SO THE ABOVE LIMITATION MAY
NOT APPLY TO YOU.
5. APPLICABLE PRODUCTS AND PERIODS. Kantronics products are of two types -
(1) hardware units and (2) firmware and software for operation of these units,
whether incorporated into the units themselves or separate from the units as
adjuncts or accessories to the units. Hardware units and the media containing
firmware, software and documentation are sold to the consumer purchaser and
become property of the purchaser. Firmware and software are licensed for use by
the consumer purchaser in return for a fee included in the purchase price of the units
and do not become the property of the consumer. (See separate License Agreement
provided with these products). The products to which the warranty of Section 1
hereof applies (herein “Applicable Products”) and the periods during which the
warranty shall apply to such products (herein, “Applicable Warranty Period”) are as
follows:
Applicable Products:
UNITS:
MT1200, KPC-3 Plus, KPC-9612 Plus, KAM XL
Applicable Warranty Period: One (1) year from date of purchase.
MEDIA:
EPROMS or PROMS, CDs, manuals (however bound), specification and
other supplemental pages or any other media on which firmware, software or
documentation are supplied
Applicable Warranty Period: Thirty (30) days from date of purchase.
6. EXCLUSIONS. This Limited Warranty does not apply to the cosmetic appearance
of the Applicable Product; to broken or cracked cabinets; to any accessory not
supplied by Kantronics which is used with the Applicable Product; to any product
that has been subject to misuse abuse or overvoltage; to any product that has been
modified by non-Kantronics personnel unless specifically authorized in writing by
Kantronics; or to any product damaged or impaired by shipping (whether or not
caused by poor packaging), neglect, accident, wiring not installed by Kantronics,
improper parameter settings which are cleared by performing a hard reset, or use in
violation of instructions furnished by Kantronics or of generally accepted industry
practice. Kantronics does not warrant that the functions contained in any software
will meet your requirements or achieve your intended results; or that operation of
any software will be uninterrupted or error-free or without effect upon other software
used with it. Responsibility for the selection of the hardware and software program
to achieve your intended results rests with you.
5

7. REMEDY PROCEDURE. Should you need to make a warranty claim, first contact
the dealer from whom you purchased the product. If the dealer is unable to assist
you, contact Kantronics Co., Inc., by mail at 3115 W 6th Street, Suite A, Lawrence,
Kansas 66049 USA; by fax at 785-842-2031; or by phone at our Service / Technical
Support number 785-842-4476 (Hours: 8:00 a.m. to 12 noon and 1 p.m. to 5:00 p.m.
Central Time, M-F). Contact us prior to returning an Applicable Product to receive a
Return Authorization Number. (As a practical matter, problems can often be solved
in such a manner without the product having to be returned to Kantronics for repair
or replacement.)
Return of any Applicable Product for the enforcement of rights under this Limited
Warranty shall be at your expense. Any product returned for warranty service, which
Kantronics determines to be without defect or not covered by this Limited Warranty
shall be subject to the minimum charge for labor and the product will be returned to
you at your sole expense. Please note, no warranty service will be provided until
Kantronics has been furnished with your Warranty Registration card and copy of
proof of purchase establishing purchase date.
8. NON-ASSIGNMENT. This Limited Warranty is not assignable by you. Any attempt
to assign or transfer any of the rights, duties, or obligations hereof is void.
9. OTHER RIGHTS. This Limited Warranty gives you specific legal rights and
you may also have other rights, which vary from jurisdiction to jurisdiction.
6

Return/Repair Procedures
Important: Our repair statistics show that over 70 percent of the units returned for
service do not, in fact, require any service. Therefore, we advise you to please double-
check the following list of common, user-solvable, sources of difficulty before contacting
Kantronics about returning your unit for service.
Check-List for Possible Problems
Should you encounter difficulty in getting your equipment to “talk” to your computer,
please perform at least the following limited checks before calling or writing:
Carefully check your wiring connections to the RS232 port.
If you purchased third-party cables, double-check to be sure that they conform to the
Kantronics’ wiring instructions in this manual.
Verify your terminal baud.
It may be useful to perform a “Hard Reset”. (See Hard Reset section.) If service or
repairs still appear necessary after you have checked the items listed above, it may be
wise to call, fax, e-mail or write Kantronics to determine if the problem can be solved
without returning the unit.
Return Procedures
When calling, report the product name and ask for the Amateur Radio Service
Department. Please have the following information available:
The unit name and serial number (the serial number is found on the bottom of the unit).
The firmware version number (the version number is displayed when you give the
Version command).
If possible, you should have the unit and your computer available to perform
troubleshooting operations when you call.
The Service Department telephone hours are 8:00 AM to 12 noon and 1 PM to 5:00 PM
Central Time, Monday through Friday. If you call outside these hours, the phone will just
ring. The service department telephone is not connected to the main switchboard and
the switchboard receptionist cannot transfer you to the service number. If lines are busy,
you may wish to (and it may be faster to) contact service by letter, fax, or e-mail.
Service e-mail is currently checked twice per day. Before contacting us, please take the
time to list out your problem fully and carefully.
7

Here is our contact information:
Kantronics Co., Inc.
3115 W. 6th St, Suite A
Lawrence, KS 66049
service phone line: 785-842-4476
service fax line: 785-842-2031
service e-mail address: [email protected]
website address: www.kantronics.com
When writing, faxing, or e-mailing Kantronics, include a clear description of the problem,
unit name, firmware version, computer type, computer software used and if possible a
list of current parameter values for your unit (as shown in a DISPLAY listing). Be sure to
include a return fax number and/or e-mail address.
Returns to the factory for refund or exchange are strictly regulated. Any return for refund
or exchange, must be approved by the service department.
Charges
Consult the limited warranty policy in this manual for the service provisions offered by
Kantronics at no charge. This warranty is considered to be in force only when the
customer has submitted his completed warranty registration within 60 days of purchase,
and when the stipulations of the warranty have been met.
Violations of warranty clauses will automatically void the warranty and service or repairs
will be charged to the owner.
Service outside the warranty period will be charged at the cost of parts, labor, and
return shipping. Units returned for service without a Return Authorization number will be
subject to a minimum charge of 1/2 hr labor plus shipping and handling.
Contact the Service Department at 785-842-4476 (Hours: 8:00 a.m. to 12 noon and 1
p.m. to 5:00 p.m. Central Time, M-F) to obtain a Return Authorization number. Repaired
units will be returned via UPS C.O.D.
These C.O.D. charges can be avoided by including your VISA or MasterCard number
with your unit to be repaired. Shipping and repair may then be charged.
8

International Returns
This section applies to international returns only, not to domestic returns.
In case of unit problems, first contact the dealer from whom you purchased the product.
If you must return a Kantronics product to us, please observe the steps outlined below.
It will save you, the customer, and Kantronics unnecessary difficulties and expense.
♦All returns must be shipped to the factory at 3115 W. 6th St, Suite A, Lawrence,
KS 66049 U.S.A.
♦All expenses of returning items to Kantronics must be paid by you, including any
duty/entry fees, whether the return is for warranty or non-warranty repair.
♦Usually, the best way to return items to us is by mail. However, if you wish to use
one of the courier services such as DHL, UPS Expedited, Federal Express, etc.,
be sure to use DOOR-TO-DOOR service. If you use one of these services, a
commercial invoice may be required. Please check with your carrier before
shipping.
♦Include in the description of the items on the paperwork (whether postal or
courier) the words:
“U.S. GOODS RETURNED FOR REPAIR/REPLACEMENT”
An additional description of “Amateur radio peripheral equipment”, or “Data
communications equipment”, would be helpful. It would also be helpful (but not
required) to include the code number 9801.00.0000 which tells U.S. Customs
agents that the package contains “U.S. goods returned without
improvement/enhancement”. However, if the words “U.S. goods returned for
repair/replacement” are on the paperwork, the number is not really necessary.
♦
Provide a value for customs purposes. This is usually the value of the item(s) in
their current condition. A $0 value is not acceptable for U.S. Customs.
♦
Inside the package, with the item(s), include:
•a fax number and/or e-mail address (if available) in case we need to
contact you
•a correct and full address for return
9

•method of payment to be used for any charges (if MasterCard or VISA,
include expiration date)
•a brief description of the problem
•a reference to any conversations with the technical/sales staff about the
problem
•and the Return Authorization number assigned.
♦
For warranty repairs, we will pay the shipping charges to return the item(s) to you
via air parcel post. If you wish return by courier service, include your account
number. To be eligible for repair under warranty, we must have a record that you
sent your Warranty Registration form and proof of purchase to Kantronics, and
the item(s) must still be within the warranty period at the time the return is
authorized.
♦
For non-warranty repairs, you must pay the return shipping charges.
10

Radio Frequency Interference Statement
Note 1: This equipment has been tested and found to comply with the limits for a Class
B digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to
provide reasonable protection against harmful interference in a residential installation.
This equipment generates, uses and can radiate radio frequency energy and, if not
installed and used in accordance with the instructions, may cause harmful interference
to radio communications.
There is no guarantee that interference will not occur in a particular installation. If this
equipment does cause harmful interference to radio or television reception, which can
be determined by turning the equipment off and on, the user is encouraged to try to
correct the interference by one or more of the following measures:
•Reorient or relocate the receiving antenna.
•Increase the separation between the equipment and receiver.
•Connect the equipment into an outlet on a circuit different from that to which the
receiver is connected.
•Consult the dealer or an experienced Radio/TV technician for help.
The user is cautioned that any changes or modifications not expressly approved by the
party responsible for compliance could void the user's authority to operate the
equipment. The user is also cautioned that any peripheral device installed with this
equipment must be connected with a high-quality shielded cable to insure compliance
with FCC limits.
Note 2: The shield of the cable, whether foil, braid, braid over foil, or double braid, must
be properly terminated (connected) 360°to the connector. This is usually accomplished
by the use of a metal or metalized plastic back shell, but may be implemented by direct
contact, including soldering, with metal portion of connector. Experience has indicated
that cable assemblies (with connectors) advertised as “shielded” are not necessarily
terminated properly, if terminated at all. Check cable construction to be sure.
11

RFI Suppression
In moving to the world of digital communications via computers, a new dimension of RFI
may be encountered. In spite of the equipment manufacturers’ diligence, each new
piece of electronic equipment will react differently in each separate environment. Every
amateur station will have its own unique layout, equipment variation, and antenna
installations. Experience has shown that these differences are related to the total RF
environment, and may be causative factors in RFI induced problems. The suggestions
given here may assist in resolving RFI problems:
•Use shielded cable for all connections between equipment. See note 2 above
•Make all interconnecting cables as short as practical
•A balance should be maintained between cable length and equipment proximity.
At times simply routing interface cables away from the video monitor or other
devices, will solve a “screen hash” or electrical noise problem
•Feed-lines to antennas should be kept away from equipment control lines and/or
interconnecting cables. If it is necessary for such lines to cross each other, they
should do so at 90°angles
•Ground leads should be as short as possible and go to an EARTH GROUND
•Interconnecting cables appearing to act as radiators or antennas should be
looped through a toroid. Be certain toroids, if used, are designed for the
frequency in use
12