Jim Brown wrote:
>>> My Cookbook is based on measurement of hundreds of chokes, all of them
>>> wound on four cores at my measured tolerance limits of the 100 or so 2.4-in
>>> o.d. and 4-in o.d. cores in my stash. Measured complex Z for each ham band
>>> was collected in a spreadsheet for each "limits" core, and for each choke,
>>> the published value of Rs is the worst case (lowest) value for each choke.
Jim, I'm having trouble correlating some of the information in your
2018 Cookbook ( http://k9yc.com/2018Cookbook.pdf ) with some of your
sample sweeps. I wonder if you could help me figure out where I've
gone off the rails.
At the bottom of Cookbook page 8 (Table 5) you show this spreadsheet
for a varying number of RG400 turns on a single 2.4" #31 core:
http://k9yc.com/Chokes-2r4inRG400.png
For example, 13 turns at 14 MHz shows an Rs value of 5379 ohms. I
*thought* (perhaps mistakenly) that the Rs value shown was the minimum
to be expected over all the #31 samples you tested.
However, in document "Fair-Rite #31 vs. #43" (
http://k9yc.com/Fair-Rite.pdf ) on page 13 for sample "GA2" I see
marker 9 at 14.39 MHz on the magenta trace with a value of 4724 ohms
and on page 14 for sample "0518-7" I see marker 9 with a value of 3267
ohms. Both of those samples appear to have ~14 MHz Rs values lower
than the spreadsheet value.
Another example is for 15 turns at 7 MHz. The spreadsheet shows 5614
Rs ohms. Page 12 of the Fair-Rite.pdf document shows marker 5 at
6.999 MHz having an Rs value of 5297 ohms, again lower than the
spreadsheet value.
At the bottom of Cookbook page 11 it says "By measuring so many
toroids and chokes, I’ve tried to increase the likelihood that the
chokes we wind will have Rs higher than Cookbook values." Yet the
three examples above all have Rs values lower than Cookbook values.
What am I missing?
Thanks!
Dan, AC6LA
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