2
Introduction
1.1 General Description and Purpose
The AT-AUTO(tm)first went into production in 2006. Over time, the AT-AUTO(tm)hard-
ware and firmware features have continued to evolve and improve. One such hardware feature
subsequently developed (and therefore lacking in the 2006-2008 AT-AUTO(tm)year models)
is the QRO Keyline.
The QRO Keyline hardware was developed in 2008 as a method to prevent damage to
an HF amplifier when inadvertently driving mis-tuned loads. The QRO Keyline feature was
then included in all 2009 and subsequent models of the AT-AUTO(tm). AT-Autos(tm)so
equipped with the QRO Keyline are able to automatically permit/inhibit keying of an HF
amplifier. Use of the QRO Keyline hardware is entirely optional and completely independent
of the automatic tuning process and does not otherwise change or alter the operation of the
AT-AUTO(tm).
With the QRO Keyline, the user may configure the AT-AUTO (tm) to automatically
prevent an HF linear amplifier from being keyed if the SWR exceeds a user-selectable level,
to immediately unkey an HF amplifier should the SWR become excessive, or while the AT-
AUTO(tm)is tuning. This may be particularly advantageous when using the AT-AUTO(tm)
with HF amplifiers that feature SWR protection circuitry. If the user neglected to unkey
the amplifier while the AT-AUTO(tm)is tuning, the amplifiers self-protection circuitry would
likely disable the amplifier, necessitating a reset of the amplifier itself.
In normal operation, the AT-AUTO(tm)uses the QRO Keyline interface to automati-
cally inhibit keying of an HF amplifier while the AT-AUTO(tm)is auto-tuning and then
automatically permits keying of the amplifier once automatic tuning has completed.
Prior to the introduction of this “QRO Keyline Upgrade Kit”, upgrading an AT-AUTO(tm)
was costly – requiring replacement of the entire processor circuit board. This modification
kit was developed to provide a very cost-effective solution to adding QRO Keyline capability
to early models of the AT-AUTO(tm)(produced prior to 2009). AT-AUTOs(tm)produced in
2009 and thereafter included the QRO Keyline hardware.
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