DOCNUMBER 9500
Document Issue 1, Revision 7
June 2009 Page 9–5
Alpha Radio Products Alpha 9500 HF Linear Amplifier Operating Manual
Product Release 1 Diagnosing Faults
Fault code 3
Description Soft Ip trip.
Explanation The current in the high voltage (HV) circuit is greater than 1.6 A.
Normal plate current for the amplifier at 1.5 kW output power is in the
range 0.8 to 1.1 A. Above this value, the tube may be at or above its rated
plate dissipation. This trip is set so that, if the plate current exceeds 1.6 A
for a short time, it trips and goes into bypass mode. You should
investigate the cause and resolve the problem to avoid damage to the
amplifier.
Resolution
•
Ensure that the drive power to the amplifier is not too high. This could
be because of a problem at the exciter. Put the amplifier in bypass
mode and transmit with the exciter. The power should normally be 65
W or less, normally more like 50 W. It is even possible that the exciter
has a problem that is causing it to put out brief high power spikes. It
is possible that the exciter and amplifier are interacting to produce
this effect.
Fault code 4
Description Hard Ip trip.
Explanation The amplifier has tripped completely off, and you have turned it on again
to either of the ON positions. The HV circuit current exceeds about 2.5 A.
The mains board contains a latching relay and associated circuitry that
trips when the current reaches that level.
Under most circumstances, the mains board reports a fault 3 (soft Ip)
when the plate current exceeds 1.6 A. If this software fault does not
happen, a hardware circuit kicks in and essentially unplugs the amplifier.
This is normally caused by a direct arc from the HV circuit to ground,
inside the tube or elsewhere.
Resolution
•
Reduce the drive power or retune the amplifier.
Fault code 5
Description Vp under voltage.
Explanation 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.
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