RF probe diode question

[Vic K2VCO]

A quick question:  I need an RF probe (my scope is broken).  I can't
find a 1N34.  I measured the forward voltage drops on various junkbox
diodes and the 1N91's show about 0.11 V.  This seems even *lower* than
what I expect from a 1N34.  Any reason not to use a 1N91 for this?
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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[N2EY]

In a message dated 11/26/06 7:41:27 PM Eastern Standard Time, [hidden email]
writes:


> I measured the forward voltage drops on various junkbox
> diodes and the 1N91's show about 0.11 V.  This seems even *lower* than
> what I expect from a 1N34.  Any reason not to use a 1N91 for this?
>

1N91 is germanium, like the 1N34.

But while 1N34 is a small-signal diode, 1N91 is a power rectifier. That means
a lot more capacitance and back leakage. I don't know if that will matter.

73 de Jim, N2EY
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[Vic K2VCO]

[hidden email] wrote:

> 1N91 is germanium, like the 1N34.
>
> But while 1N34 is a small-signal diode, 1N91 is a power rectifier. That means
> a lot more capacitance and back leakage. I don't know if that will matter.

I found a 1N45.  That is pretty similar to a 1N34, so I'll use it.  The
drop is about 0.28V.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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[Geoffrey Mackenzie-Kennedy-2]

Vic,

Having blown up my share of probe diodes, I find it useful to stick a label
on any such homemade probe noting its maximum safe peak working voltage
derived from the diode's PIV rating.

73,
Geoff
GM4ESD

----- Original Message -----
From: "Vic K2VCO" <[hidden email]>
To: <[hidden email]>
Cc: "Elecraft Reflector" <[hidden email]>
Sent: Monday, November 27, 2006 2:48 AM
Subject: Re: [Elecraft] RF probe diode question

> [hidden email] wrote:
>
>> 1N91 is germanium, like the 1N34.
>>
>> But while 1N34 is a small-signal diode, 1N91 is a power rectifier. That
>> means a lot more capacitance and back leakage. I don't know if that will
>> matter.
>
> I found a 1N45.  That is pretty similar to a 1N34, so I'll use it.  The
> drop is about 0.28V.

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