>
>> >my guess was a sudden overload. The event was so brief that there
>> >was no damage to the outside of the resistor -- even though the
>> >resistor element
>> > was almost burned out.
>
>The reflector has been down this road before.
>
>I have found hundreds or perhaps thousands of carbon composition
>resistors that behaved that way, even when used well bel0ow the
>ratings in dc or low-frequency AC circuits. Many others report the
>same.
>
>That is why carbon resistors have fallen from favor in critical
>applications, especially when in hot environments.
>
>> >>>>Were these amps that were measured while exhibiting intermittent
>> >>>>vhf oscillation damaged in any way by the oscillation?
>> >>>
>> >>>the vhf suppressor-R was typically damaged. The resistance
>> >>>suddenly increased 2x - 4x.
>
>This claim would only be valid if the resistor was measured
>immediately before failure and found perfect, that there was a
>confirmed VHF oscillation, and that when checked again
>immediately after the value changed.
>
>One can not use an "it was off value, so it MUST have been a VHF
>parasitic" as proof of the cause of damage. Many things, including
>temperature and time, cause carbon resistors to go off value.
>
>
This situation is different because the damaged resistors appeared to be
in mint condition on the outside. IOW, the damage took place at a rapid
rate.
end
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
--
FAQ on WWW: http://www.contesting.com/FAQ/amps
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
|