Hi everybody
I have been wondering a bit about how to actually measure the Q of the
plate tank of an amplifier. Of course I have been looking around a bit
and I have two different things that kind of contradicts each other, at
least from what I understand. Or I have missed something.
First, there is the method of using for example an MFJ 259B, which is
explained here,
http://web.archiveorange.com/archive/v/0RLC1crR63v6fj2qn5uL
By this method they use the 2:1 VSWR bandwidth to determine the
bandwidth of the filter and thereby calculate the Q-value. This is OK if
it is actually the "antenna bandwidth" that does determine the Q-value
in a Pi-tank.
Another method is to use the same as for example when measuring the
Q-value of a BPF, where we use the -3dB point as a measure of the
bandwidth (half power).
But for me 2:1 bandwidth and -3dB point is not the same, or have I
missed something?
Mike, SM2WMV (SJ2W)
http://www.sj2w.se/contest/
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