[Elecraft] 1N34A-Diode,RF probe

[Nick-WA5BDU]

It's common to recommend a Schottky as a replacement for the 1N34A.  
I've done it myself.  That's why I was surprised to find this web page -

http://www.cliftonlaboratories.com/diode_vf_vs_if.htm

where this guy discovers that the Schottky diode (1N5711, to be 
specific) can show some pretty high forward voltage drops.  Turns out 
that the low drop we're all familiar with exists at quite low values of 
forward current -- less than 1 mA.  At ~2 mA is a sort of breakpoint 
where Vf begins to increase at a faster rate than in the silicon or the 
germanium diodes.  By ~10 mA, the 1N5711 has the highest forward voltage 
of all three. Quite an eye-opener!

You might think that for the RF probe application, forward current will 
be small.  Maybe it is.  But often times small average currents are 
misleading if there's a short conduction angle (time).

72--Nick, WA5BDU

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