[PVRCNC] MFJ-259B inductance measurement

[Mike Barts]

I'm building some loading coils for my 40m beam. I designed the coils 
using several of the online calculators as sanity checks. The final 
design is built using 1/4" copper tubing, 5" air coil supported by 
two 3/4" strips of Delrin. The design inductance is 2.64 uH. When 
measured by my MFJ-259B in inductance mode, it's measuring a little 
over 4 uH. I've got the inductor suspended by a string, hanging in 
the air in the garage to minimize coupling. Anything metallic (except 
the -259B case) is at least a foot or two away. The lead lengths to 
the MFJ-259B are about 6" long.

Are there any known issues with inductance measurements with the 
-259B? (yes, other than it being an MFJ product....) While I didn't 
expect an on the money inductance, 4 vs 2.6 is a big error. Don't 
think the lead lengths are THAT long to add almost 2 uH, and I don't 
think my inductor design is THAT far off.. Looking to see if I'm 
missing something obvious or there are issues I'm not cognizant of. 
All suggestions, other than trashing the -259B, welcome.

73, Mike N4GU