Hi All,
Tom said:
> A good meter is more reliable than a scope.
What does that mean? Meters have a longer MTBF than Oscilloscopes?
The waveform envelope is limited by filters to 3000 Hz, an audio limit. But
does not the FCC regulations state that the power is to be measured over one
RF cycle?
At 30 Mhz = 33.3 nano-seconds
At 1.8 Mhz = 555 nano-seconds
The rise time of a system is related thus: BW x RISETIME = CONSTANT = 0.35
0.35/3000 = 117 micro-seconds. The peak rectifier circuit time constant
should be designed to get the information as quickly as possible ( but not
quicker) , so that subsequent following pulses are not ignored. If the
rectifier time-constant is 40 micro-seconds, then in 3 time constants most of
the prior information will be bled off and the circuit will be ready for the
next pulse. Some of the circuits I have looked at had 15 millisecond
time-constants. Somehow either I am missing something very simple or my logic
is faulty!
I think Rich is using a good system. The bandwidth of the scope is more than
adequate and will not miss in-between pulses.
The FCC says power is measured over one RF cycle.
Regards,
BillW KB7YUM
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