Manfred, Have you ever compared the Q readings measured by the old BRC-160 or the Hp 4342 Q meters against the Q reported by any network analyzer or even many of the older 4 terminal instruments from the 70's and 80's and maybe into the 90's? The old Q meter uses a parallel resonant circuit technique and this was considered the best method until technology caught up. I had to work with inductor suppliers using "modern" instruments to measure Q when we were using the tuned-circuit method. Big difference in the reported Q. Then things started to agree as the 4 terminal methods improved. Yes, the resistance is so low compared to the reactance that is is difficult to get an accurate or true Q.
