[Lowfer] 600MRG> Question about parallel diodes

[dave.riley3]

Hi Andy,

A poor man's noise generator @ microwave consists of a uW diode such as 
1N23B reversed biased and decoupled which will cause detection in a decent 
front end @ 10 Ghz...

This is the basis of commercial NOISE sources, and when amplified become 
noise source STANDARDs...

It worked well here with cobbed up front end, first pointing the dish @ blue 
sky, then Sun, then Earth and able to detect three different noise levels, 
it is then time to put the tools away and start receiving cvuz looking on 
the horizon, you will see EARTH noise then is then the limiting factor...
Using 'noise' to tune the front end gets you to the threshold...

But @ LF I'm not sure cuz I havn't tried it, but an amplified noise source 
can be heard OK...
The ambient noise down here is usually well about a bare bones diode 
though...

I would run mine from a 5 volt square wave turning the diode on and off @ 
about one second intervals, then looking on scope @ the detector to see 
relative S/N ratio while tuning...
It has to do with hole flow within the diode and electron agitation, the 
grandmother of all noises...

Hope this helps...


TNX fro Dave @ /17






----- Original Message ----- 
From: "Andy - KU4XR" <ku4xr at Yahoo.com>
To: "600 meter group" <SHMRG at piobaire.mines.uidaho.edu>; 
<lowfer at mailman.qth.net>; "Part-15 Yahoo" <part15 at yahoogroups.com>
Sent: Sunday, June 06, 2010 12:48 AM
Subject: 600MRG> Question about parallel diodes


> Thanks for any replies: I have just recently come to understand that
> a diode can be, or make noise in a circuit. Frankly, I had never
> considered that before, until Charlie - W5COV began discussing it
> with me on power supply topics. It finally dawned on me that a
> diode " clips " the voltage peaks of a sine wave, this inherently
> creates noise in the process by distortion of the signal voltage.
> OK, my question: In theory, or real world practice, would putting
> 2 diodes in parallel help in any way to lower the noise it might
> generate, OR ::: would it in fact double the noise generation.
> I'm not approaching this concerned about current handeling, I'm
> specifically curious about the diode noise. And to clarify; the
> diodes will be anode to anode / cathode to cathode, not anti -
> parallel.
> Looking forward to the education; 73 all :::
>
>
>
> Andy - KU4XR - EM75xr - Friendsville, TN. USA
> LOWfer Beacon " XR " @ 185.29875 KHz ( QRSS-60 )
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