Paul Burridge wrote:

Hi guys,

I have some surplus axial inductors marked as follows:

uH27 -K
GEL

I would have thought this implied 0.27uH or 270nH? GEL is presumably
the maker. However, there's no resonance at 17.6Mhz with 300pF in
parallel as might be expected of an inductor of that value. There *is*
however, a resonance at 50.6Mhz., which implies that the inductors are
actually 33nH. I'm confused. Anyone have any idea as to how to
determine the value absolutely? Are makers' marking to be trusted at
all?

50MHz is pretty high -- are you sure it's not 27nH with stray
inductance? Did you measure more than one to check for tolerance as the
OP brings up?

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Tim Wescott
Wescott Design Services
http://www.wescottdesign.com