Allison, can you explain more about how earlier stages would become unstable due to a changing bias voltage? I don¡¯t quite understand how that creates a Feedback condition?
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On Jul 1, 2023, at 15:13, ajparent1/kb1gmx <kb1gmx@...> wrote:
?The transfrmers do not have enough iron to create spikes.? The spikes are the earlier stages
going unstable as the bias line drops voltage slowly.
Also BIAS to the IRFZ24... the voltage has to be enough o establish the desired no signal
Drain current.? If incorrectly adjusted or a circuit fault due to previous blown IRFZ24s the
likely result is too high bias applied and more blown IRFZ24s.? The no signal (no
modulation or power out but in TX mode) current should be about 100mA.??
The likely fault if the IRFZ get s agate to drain short is a burnt out bias pot making proper
adjustment difficult or impossible.
If the above is not paid attention blown finals will be a repeat offender.??
The addition of protective Zeners may help but first it has to be working
properly to start with.
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Allison
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Please use the forum, offline and private will go to bit bucket.
