[NLRS] Calculating 1/4 Wavelength coaxial stub?

[Scott]

To make a shorted 1/4 wavelength stub, I would have thought that the 
formula would be (234/f)*Vf where f is the frequency and Vf is the 
velocity factor of the coax.  Searching google briefly, I saw a site 
that had the formula as (246/f)*Vf.  Of course at 1152 MHz, that's 
"only" a difference of about 2mm.  Which formula will get me closer?  
Or...is there a different one alltogether?

-- 
Scott N0EDV
http://corbenflyer.tripod.com/
Flying Corben Junior Ace - Building RV-4
Gotta Fly or Gonna Die