Quote:
Originally Posted by Penthode
You should not worry about keeping anyone up late. You have provided accurate facts. It is just that sometime the HP engineers were trying to be too clever (my opinion). When troubleshooting, the power supply often provides clues to what is wrong and right now we are only attempting to understand what is wrong. The understanding of the power supply sheds new light and the fact the +20v is spot on and the -6.3v is a bit low to me is not yet a red warning.
Let's review the symtoms again:
"...Have a very low power clean 12.5MHz sine wave. The frequency doesn't change whatever I do to the wheel and the output level has no effect on the amplitude. The meter still doesn't move into the readable zone..."
To me this again is pointing to the output hybrid amplifier. I think we should step back and reflect how to confirm this.
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Let me be a bit more specific about the symptoms. The output level DOES have an effect on the amplitude in that whenever you select anything other than a +10dBm level, the signal goes away. The 12.5MHz CW is visible on just that one intensity setting.