>That's K4AUW Dennis. Glad you are back up and running.
>73....Ron
>
>On Mon, 22 Sep 1997 07:16:42 -0400 CATALANO_DENIS_E@hq.navsea.navy.mil
>writes:
>> I have finally got the Centurion working again. Thanks to all
>>for the trouble shooting suggestions. KA4AUW (Ron) gets the prize. He
>>was right on saying it probably is the HV transformer followed by one leg
>> of the diodes. That's exactly what it was. The primaries of the
>> transformer had continuity, and 5 diodes were bad. What went first,
>> and what caused it, is a mystery to me.
Mysterious indeed. Diodes don't usually fail when a transformer develops
a short across its secondary.
>>Tentec seems to think a
>>line surge or lightning strike was the cause. There was no visible
>> physical damage, nor was anything else fried.
A lightning strike usually damages the HV electrolytic filter capacitors.
- I have heard about HV transformer failures occuring in some models of
Henry amplifiers during a HV arc to ground. None of these amplifiers use
a 'glitch' R in the positive HV circuit to limit fault current. However,
the Centurion uses a 10 ohm 25w 'glitch' resistor. The plot thickens. I
don't buy the lighning 'explanation' because there would have been
peripheral evidence of such.
- I would be inclined to inspect:
1. the safety vents of the electrolytic filter capacitors.
2. the glass coating on the glitch resistor.
- I would be inclined to measure:
1. the resistance of the VHF suppressor resistors.
2. the grid/filament withstanding V at 3 - 5uA of leakage.
3. the resistance of the glitch resistor.
Rich---
R. L. Measures, 805-386-3734, AG6K
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