A month or so ago, several on these NANO sites requested more information
on the CMCs I had wound and measured using the HP-8753C. I'll attach a
more in-depth description - see the attachment. If there are questions,
please email me back on the appropriate group.io . If pictures are
required, let me know.
Each CMC is wound in bifilar manner with no twists or cross-overs in the
windings. In most cases, the number of turns is all I could fit on the
specific set of ferrites. The 31 material is an obvious overkill, but I
reasoned due to the higher µr of the material especially at 160-meters, it
would have to support more circulating magnetic current than the other
materials. The noted "GRN" and "BRN" is to denote the color wire to
distinguish between the various chokes. The noted AWG #14 is insulated,
stranded, and flexible 'antenna' wire from Davis RF.
Dave - WØLEV
Beware of cheap underperforming clones
As of 2022 there are many badly performing clones on the market. V2/3GHz NanoVNA uses parts like ADF4350 and AD8342 which are costly and clones have been cutting costs by using salvaged or reject parts.
See official store and look for V2 Plus4/V2 Plus4 Pro versions only to avoid getting a bad clone. We have stopped selling V2.2 versions since October 2020, so all V2 hardware that are not Plus or Plus4 are not made by us and we can not guarantee performance.
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COMMON MODE CHOKE INFORMATION
David Eckhardt 2021/01/14 22:51
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