Specifications

6
DOCNUMBER 9500
Document Issue 1, Revision 7
June 2009 Page 6–5
Alpha Radio Products Alpha 9500 HF Linear Amplifier Operating Manual
Product Release 1 Operating the Amplifier
We recommend that you check the plate voltage. To do this, tap the Vp
button and watch the digital meter. It should be in the range 3400 to 3650.
State 3 (Standby) To enter this state from State 2, wait until the three-minute timer reaches
0.
In this mode, the exciter is able to use the antenna, but the amplifier is not
amplifying the signal.
Certain faults cause the amplifier to return to this mode.
State 4 (Operate, unkeyed) To enter this state from State 3, wait for the amplifier to warm up and
press the OPER button. Or issue the command for the OPER mode from
the serial interface.
The amplifier is fully warmed up, but the key-in line has not been
activated. The tube is biased to a very low current, and the exciter is still
connected to the antenna.
State 5 (Keyed, no RF) To enter this state from State 4, wait for the key-in line to be shorted to
ground by the exciter.
The input and output relays are activated, and the exciter is now
connected to the input of the tube.
!
IMPORTANT The phrase “keying the amplifier” throughout this manual means to
move from State 4 to State 5.
State 6 (Power) To enter this state from State 4 or 5, wait for the amplifier to sense RF.
The tube is biased to its operational condition, and the amplifier measures
the frequency of the RF and attempts to match its operational condition to
the drive frequency and power that it senses.
If the frequency of the input signal indicates that a band change is needed,
the amplifier briefly unkeys to avoid damage to the bandswitch.
In this stage, you cannot activate the antenna selection features. This is
done to avoid hot-switching the relays.
The amplifier is now fully operational and delivering power to the load.
6.4 Tune the Amplifier
The ALPHA 9500 has an autotune feature for tuning to the desired
frequency. You can turn the feature on and off. You might want to turn it
off, for example, if there is heating in the antenna, coax, tuner, or balun
transformer, which might cause the amplifier to unnecessarily keep
tuning. The newest firmware has autotune hunting disabled; however, the
LED is still on, indicating that the autotune feature is still active.