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USER'S GUIDE
APPENDIX D – AMTOR OPERATING SUGGESTIONS FROM G3PLX
Introduction
The following text is reproduced verbatim from a letter from Peter Martinez, G3PLX, dated
9/24/84, on the subject of good AMTOR operating practices. This paper is reproduced here by ex-
press permission of the author and is offered as a guide to AMTOR operation from the one man
most responsible for bringing AMTOR into the amateur radio fraternity. Newcomers to AMTOR are
invited to give serious consideration to the ideas presented here.
Preface by Peter Martinez, G3PLX
Here are some thoughts on the subject of operating rules, etc., for AMTOR. They are in no particu-
lar order and are written down exactly as they occurred to me as I sat in front of my typewriter.
They represent aspects of AMTOR operating that have given rise to problems so far over here and
some (the hot QSY technique) which have been invented to complement the advantages of AM-
TOR.
1. Legalities
Establish before operating whether you are authorized to do so. Most countries where there is
currently AMTOR activity are permitted by general license regulations. Some countries require
the licensee to apply for a special permit. Some countries do not permit AMTOR. In others, sta-
tions are active!
2. Getting started on AMTOR for the first time
The most popular AMTOR mode is ARQ, since it is the most effective. However, do not attempt
to make the first QSOs on ARQ until FEC has been tested and is known to be working. If there
is a fault in part of the system, no contact will result on ARQ at all, whereas at least in one di-
rection (transmit or receive) is working, faults can be identified and cured with contact in FEC.
The following step-by-step procedure will assist in finding faults during commissioning a new
AMTOR station.
2.1.
Check FEC receive first, with a known distant station sending in the correct shift-polarity.
This will confirm the station receiver is working, and in the correct shift-polarity.
2.2.
Check FEC transmit next, asking a distant receiving station to confirm that the transmit
shift-polarity is correct.
2.3.
Make a short transmission with an ARQ call, asking the distant station to use 'listen' or 'mon-
itor' mode to check that the transmitter keying is functioning correctly. The most common
fault at this stage is a too-slow changeover from receive to transmit, resulting in missing
transmitted data at the start of the burst.
Some AMTOR units have a delay adjustment which may allow slow transmitters to be used
successfully except for very long distance contacts. Some remedial work may be required on
the radio if this test fails.
2.4.
If 2.3 is successful, ask the distant station to make an ARQ call to your SELCAL. Your station
should respond and an ARQ contact should result.
PK232UG Rev. E 9/87
AMTOR OPERATING NOTES
G3PLX September 1983
D-1
AMTOR OPERATING SUGGESTIONS FROM G3PLX
179
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