Question......
Why is it that some people say you need to add a 6" spring to a 102" whip in
order to match it? Could someone explain this?

If you do the math (234 / Freq. in MHz = 1/4 wave) it ends up being 103.29"
@ 27.185 MHz (CH 19 mid band) which if you add the mount, say a 1" stud plus
the insulators, it comes out pretty close to 103.29" not counting the inch
or so of exposed coax at the connection. I've never been able to add a
spring (rat shacks were shorter than 6") without having to cut about the
same amount off the whip in order to keep the SWR reasonable.
Thanks,
Bill