ALPHA Amplifier Frequently Asked Questions

ALPHA Amplifier Frequently Asked Questions

What is the best way to use the 87A AlphaMax functions?
When the new (since 1999) AlphaMax (Autotune) firmware is installed in
the 87A, the TUNE and LOAD LEDs will blink to indicate what the AlphaMax
program would do if it was enabled.

An addendum to the 87A manual was included with AlphaMax kits that
were installed in the field, or you can download a copy of the new
version of the 87A manual (with instructions for using AlphaMax) from
our web site:

You should tune up the amp with your antennas on each band/segment and
save the settings in USER memories. When changing bands the 87A first
goes to the USER memory setting. If further tuning is needed it will
make the adjustments if the Autotune mode (AlphaMax) is enabled. If
it is not enabled, the TUNE and/or LOAD LEDs will blink to indicate
what direction those would be moved.

If it is not in Autotune and the user settings are not at all close to
desirable, it will fall back to factory-saved default settings (for a 50
ohm load) and the DEFAULT LED will light solid. If that is not close
enough to get normal output with the current load, the amp will get a
Fault 17.

The Autotune function is enabled by pressing the LOAD^ and ENTER
buttons at the same time. The DEFAULT LED will flash when Autotune is
enabled and the amp is in operate and warmed up.

Please note that the TUNE meter is a rough indicator to allow the amp
to be tuned with low drive levels so that it is close to being set for
1500w output. Once you increase the drive and are close to 1500w out,
fine tune by adjusting the TUNE and LOAD controls for maximum output at
the drive level you are at. This should correspond to a dip in the
plate current. The TUNE LED may be a number of LEDs off center to
either side. The most useful multimeter parameter to monitor when
transmitting is the Ip (plate current), also watching the Ig (grid current).

The TUNE meter is calibrated on 20m when the amp is tuned up for
1500w out, with new tubes. As the tubes age, it will indicate off
center a bit. Line voltage that is not at the nominal value for
each range (200, 220 or 240v) may also affect the TUNE calibration.

Since the 87A has memories that should be saved for the tuneup
settings for each band segment, the TUNE meter isn't really as
useful as it is with a manually tuned amp (Alpha 89/91B/99).

How do I key the Alpha 99/91B with an Icom 746/756 radio?
The Alpha 99/91B has 25vdc @ 7ma at the RELAY jack. This is within the specs of
the OMR-109 relay in the Icom radios, although Icom says it is rated for 16v/500ma.
The problem is not the voltage rating, but the spec of the relay for operations per minute.
With NO electrical load on the contacts, it is rated for 300 operations per minute,
or about 10 wpm QSK CW. Faster than this will cause it to fail prematurely.
When there is any electrical load on the contacts, the operations per minute rating is less.
NOTE: Alpha 99 amplifiers manufactured after 15 DEC 2002
have 12vdc @ 7ma on the RELAY jack.
This web page explains it very well: Icom FAQ.

What does the TUNE function of the multimeter indicate?
The TUNE function is a 'gain' meter. It indicates that the amplifier is tuned
to good efficiency, and is calibrated to be in the center at 1500w out on 20m.
The TUNE meter may be a few LEDs off center on bands other than 20m. It
should not be used as the last indication that the amplifier is tuned correctly.

Finish tuning by adjusting the TUNE control for peak output, which should
also produce a dip in Ip. Monitor the RF output and Ip.

Should I Turn My Amp Off or Leave It On?
Vacuum tubes are like incandescent light bulbs, the filament
inside is heated and has a finite life. Two things make them
wear out; the initial stress of the current surge when turning
them on (that is usually when a light bulb burns out), and the
time that they are left on.

Alpha amps reduce the initial current surge stress by using
a small resistor in series with the tube filaments.

It is a balance between turning the tube filaments on off on off,
or letting them run for hours on end. If you will be using the amp
again on the air within an hour or so, leave it on. If it will be 2
hours or longer, turn it off between operating sessions.

Why don't I see my typed characters when using
Hyperterminal to communicate with the 87A?
The makers of Hyperterminal, Hilgraeve, have an updated version
that fixes this problem. Download a free copy from their web site:
Hilgraeve, Inc.

Back to Alpha Support Page

Last Updated on 12-Dec-02
By ALPHA/POWER