Alpha Radio 87A, Operating Manual

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Page 24
monitors the various operating parameters and
changes the tune and load controls in response
to varying levels of drive and load impedance.
AlphaMax autotune algorithms only engage at
input power levels of 30 watts or greater, where
the improvement in efficiency will provide a
significant improvement in amplifier
performance.
The optimum settings of the tune and load
controls is dependent on both drive level and
antenna impedance. SSB is an amplitude-
varying modulation and the firmware will make
adjustments during operation but may take a few
seconds to finalize the best settings for the
particular amount of drive. CW autotune
typically happens somewhat faster.
OPERATION:
AlphaMax may be engaged remotely from the
AlphaRemote software by clicking on AUTO with
the left button of the mouse. AlphaMax may
also be engaged locally by pressing the ENTER
button simultaneously with the LOAD^ button.
When AlphaMax is operating, the DEFAULT
LED will flash.
AlphaMax will attempt to make up to 80
adjustments of the TUNE and LOAD controls in
order to find the optimum settings. Under some
conditions AlphaMax will not be able to find an
optimized setting within the parameters as
defined in the firmware. Under such conditions
AlphaMax will stop hunting and the DEFAULT
LED will stop flashing. AlphaMax may be
restarted by clicking on the AUTO button in
AlphaRemote or depressing ENTER and
LOAD/UP simultaneously. (Note: Some
transceivers appear to have a power drop after a
few seconds of operation and this power drop
(and subsequent power increase after a few
seconds in receive) will tend to make AlphaMax
hunt for the proper settings for more than 80
tries and then shut off. This is a problem with
the transceiver and the transceiver should be
repaired.)
It is advisable to store different default values for
a given band and band segment as a better
starting point for the algorithms to find an
optimized value in situations where the
autotune gives up after 80 iterations.
Autotune operation may be stopped by
clicking on AUTO OFF under Alpha/Remote
or may be stopped by hitting either TUNE or
LOAD UP or DOWN buttons on either the
front panel of the 87A or under AlphaRemote.
TIPS:
The AlphaMax algorithm will tune up the 87A
into an acceptable range (or window) of
values. Manually tuning may result in slightly
better settings. For best results and fastest
operation manually tune the 87A to the best
setting for the preferred antenna and drive
level and then store these settings as the
DEFAULT values. AlphaMax will then adjust
the tuning and loading controls only when the
antenna impedance changes or the drive level
changes.
AlphaMax will attempt to tune the 87A to the
optimum gain point, which results in maximum
efficiency and lowest distortion. Under high
drive levels this may result in more than 1500
watts output. Output power should be
adjusted by setting the input drive level to the
appropriate level rather than by mis-tuning the
amplifier to reduce power output.
SERIAL PORT OPERATION:
Three new commands control autotune
operation:
AUTOTUNE - queries and returns the
autotune status
AUTOTUNE ON - enables autotune
actions
AUTOTUNE OFF - disables autotune
actions
When autotune action is disabled, the
LOAD/UP and TUNE/DOWN LEDs provide a
indication of what action would be taken if
autotune was enabled. For example, when
the grid current exceeds the threshold value
Alpha 87A User Manual Rev 2.0