RF Concepts LLC PA-77DF User Manual

Alpha 9500 Linear Amplifier User Manual

RF Concepts, LLC

Diagnosing Faults

Product Release 1

DOCNUMBER 9500

Document Issue 1.1

Page 8–6

February 2010

88

Vp under voltage.

The mains board monitors the plate voltage (HV, Vp) for approximately 
2 seconds after the amplifier is turned fully on (ON 2).

If Vp fails to reach approximately 2.8 kV during this time, the mains 
board reports this fault code.

1. Ensure that the mains board is selecting the correct primary 

transformer tap. See fault code 2 for information on how to do this.

2. If the correct primary tap is being selected, then the problem is 

elsewhere. Unplug the amplifier, remove the top cover, and inspect 
the mains board and high voltage board. Unplug each of the 
transformer connectors and inspect them for problems.

Output relay closure fail.

The master controller monitors the state of the output relay using an 
auxiliary DC bias applied through a pair of RF chokes. This allows it to 
determine that the output relay has traveled to the closed condition, and 
that it is safe to bias the tube to OPERATE mode.

•

Call RF Concepts at 303-473-9232.

Output relay may be stuck.

If the output relay appears to be closed when the amplifier is keyed up, it 
is possible that the output relay is stuck in the ÖN condition for one of 
several reasons. See Fault code 6 for more information.

•

None. You should not see this fault in the field.

Bandswitch set failure.

The stepper motor controller processor is unable to land the apparent 
bandswitch position on the correct setting within the precision required.

1. Turn the amplifier off and back on.