[Amps] AL-80B questions

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Greetings amps gurus,

A friend of mine just called me. He bought an AL-80B about 6 months ago. It's now eaten it's 4th tube. He's sent the amp back once and gotten replacement tubes the other times.

This morning he wanted to try to work some of the contest on 10M, began tuning up, said he heard a little "tick..... tick-tick" and then no output. ZSAC is about 250mA.

The other times this happened he said Ameritron told him that they'd gotten a bad batch of tubes (Amperex) and exchanged them for him.

The one time that he sent the amp in to Ameritron they said they found nothing wrong.

Having never experienced parasitic problems first hand I can't speak from experience but the last time this happened I suggested that he try one of Rich Measures' retrofit kits. He says he now has it but hasn't installed it yet.

My questions:

1: Does this sound like a symptom of parasitic oscillations?
  I thought the 3-500Z was pretty rugged with respect to faults.

2: Does anyone know of any problems with recently built Amperex bottles?

3: I'll probably help him install the parasitic supressor kit somethime this week.  Are there any other things to look for or suggested corrections to this thing that would make it less prone to eating another tube?

Thanks in advance all!


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