[Milsurplus] mhz

[Mike Morrow]

>German prewar radio, calibrated in MHZ
>Note the correct spelling is :    mHz or kHz
>The Herze name is capitalized. The mega or kilo ialong with
>the z is small letters.

No, that is **THE** most common error made in S.I. unit usage.

The prefixes used before S.I. units are world standardized.  Some are upper-case.  Some are lower case.  Little m = .001 (milli), big M = 1,000,000 (mega).  Thus, "mHz" means one-thousandth of a Hertz.  "MHz" means one million Hertz.  The second is 1,000,000,000 times larger than the first.  No one has *ever* seen a ham rig whose dial should be calibrated in mHz.  Little k = 1,000, but big K is not used in S.I. unit *prefixes.*  Then, there's a heck of a lot of difference between a 1 PF capacitor and a 1 pF capacitor (the first is 1,000,000,000,000,000,000,000,000,000 times larger than the second). 

The complete list from the National Institute of Standards and Technology at http://physics.nist.gov/cuu/Units/prefixes.html is:

Factor      Name  Prefix 
1E24        yotta       Y 
1E21        zetta       Z 
1E18        exa         E 
1E15        peta        P 
1E12        tera        T 
1E9         giga        G 
1E6         mega      M 
1000       kilo         k 
100         hecto      h 
10           deka      da 
1/10       deci        d 
1/100     centi       c 
1/1000    milli       m 
1E-6       micro      µ 
1E-9       nano       n 
1E-12     pico         p 
1E-15     femto      f 
1E-18     atto        a 
1E-21     zepto      z 
1E-24     yocto      y 

Mind those lower case and upper case prefixes.  They can make a big difference!

Mike / KK5F