Thanks Brian for steering me to this discussion. It looked like an opportunity for me to compare my measurements using this much discussed T37-6 with 8 turns. I have a bag of T37-6 that had come from Amidon (and almost for sure are Micro-Metals manufacture). So, I wound and measured one with #22 wire and one with #26 wire, all at 14.1 MHz.
#22 Wire, 260A Q-Meter L=250 nH, Q=164
#22 Wire, Insertion loss method (-46.0 dB) Q=176
#26 Wire, 260A Q-Meter L=248 nH, Q=138
#22 Wire, Insertion loss method (-44.25 dB) Q=140
A couple of notes. My 260A is really old, but through some miracle has all original tubes, including the very special detector tube. It also has the original thermocouple. It behaves just like it did 40 years ago. I have a box of "standards" that were measured in the 1960's on an almost new 260A (a different one). The checks with those are still close. Also, the 260A instruction manual notes a need for a correction due to the coupling resistor of 20 milliOhm, that appears in series with the inductor. This needs to be subtracted for low series resistance inductors. I did that for the numbers shown.
The attached shows how they look physically.
My Q numbers are enough lower than Brian's to be interesting to track down. Brian, can I mail you the coils?
Bob W7PUA
