[Elecraft] 1N34A-Diode,RF probe

[Ron D'Eau Claire]

Right on, Don. Like Jim, I often turn to the 1N5711 when a 1N34 isn't
available. The 1N5711 has a forward drop of about 0.35 V max. It's very
common and inexpensive here in the USA so I'd expect it to be available
almost anywhere.

Types to avoid are the common "switching" diodes such as the 1N914 or the
1N4007.

Ron AC7AC

-----Original Message-----


Chris,

The 1N34 is specified because it is a germanium type and the low voltage 
drop of the germanium junction is preferred for accurate readings at low 
RF Voltage levels.  Other germanium diodes will do that task just as 
well.  Watch the peak reverse voltage rating for the diode you choose, 
because that will limit the maximum RF voltage that you can measure 
without zapping the diode.

A silicon diode can also be used for an RF Probe, but its accuracy at 
low RF Voltage measurements will not be as good because of the higher 
diode forward voltage.  We are talking about the difference between 0.3 
volts and 0.7 volts between a germanium diode and a 'run of the mill' 
silicon junction diode.  The Schottky diodes are silicon and have a low 
forward voltage drop and should work fine in RF Probe applications.

73,
Don W3FPR

OE5CSP-Chris wrote:
> Hi,
>
> I´d like to build the Rf probe from th K2 kit.Elecraft says I need a
> 1N34A Diode, but this one is hard to get in my small town.Can I take 
> another one and which diode should I take?
>
> 73,Chris-OE5CSP
>   
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