[Elecraft] The Dummy Load Noise Generator

Mon May 19 09:00:00 2003

Hi

You should be getting a S9+ signal out of the noise generator on all bands
up through at least 440 MHz. If the voltages on the collectors of Q1 and Q2
are ok then you may want to try another Q3. Some of the transistors do not
generate as much noise as others. Q3 is the noise generator. Also check the
battery. If it is below 8 volts then the noise output will be low. This
circuit eats batteries. A 9 volt will only last a few hours so remember to
turn the noise generator off when not needed. I included a LED and limiting
resistor in the kit to use as a power on indicator.

Don Brown
KD5NDB

----- Original Message -----
From: "Mike Walkington" <[email protected]>
To: "Don Brown" <[email protected]>
Cc: "Elecraft Reflector" <[email protected]>
Sent: Sunday, May 18, 2003 11:37 PM
Subject: Re: [Elecraft] The Dummy Load Noise Generator

> Hi Don,
>
> You were spot on, the 680 ohm resistor had gone and taken out the one next
> to it. The two amplifying transistors had gone as well.  All replaced and
> the noise generator seems to be working well now, although only generating
> about S2 at 80m and the signal starts to fall off at 20m.  Plenty enough
to
> align the filters after I had done the 2nd crystal filter mods, but any
> suggestions on why the signal would be down?  I'm tempted to believe that
> the K2 S meter is a bit stingy, and it and the AGC are the next things I
> need to look at.  I'm quite happy with the shape of the filters now.
>
> Mike
> K2 - #2599
>
>
>
> ----- Original Message -----
> From: "Don Brown" <[email protected]>
> To: "Mike Walkington" <[email protected]>
> Cc: "Elecraft Reflector" <[email protected]>
> Sent: Friday, May 16, 2003 6:21 AM
> Subject: Re: [Elecraft] The Dummy Load Noise Generator
>
>
> > Hi
> >
> > I thank this happens more than most people want to admit. I put a
warning
> in
> > the instructions about this but it is still easy to do. It will usually
> zap
> > the 680 ohm resistor and one or two of the transistors depending on how
> many
> > watts you fed back into the generator. It is a good idea to set the
power
> > control to minimum then disconnect the key and/or mike when using the
> noise
> > generator and stay away from the tune button. Almost any small signal
NPN
> > transistor will work 2n3904 2n2222 2n4401. After several glasses of some
> of
> > our fine Texas wine, I find messing about with radios is not a good
idea,
> > but I have been known to do it anyway. ;-)
> >
> > Don Brown
> > KD5NDB
> >
> >
> > ----- Original Message -----
> > From: "Mike Walkington" <[email protected]>
> > To: <[email protected]>
> > Cc: "Elecraft Reflector" <[email protected]>
> > Sent: Thursday, May 15, 2003 10:37 PM
> > Subject: [Elecraft] The Dummy Load Noise Generator
> >
> >
> > > Hi Don,
> > >
> > > One glass of red wine, not enough attention being paid to what I was
> doing
> > > and suddenly the noise generator goes into service as a dummy load.
An
> > > acrid smell, one black resistor, two transistors with small bulges are
> the
> > > obvious signs of damage.  Has this happened to anyone else?  Before I
> pull
> > > it apart and see what needs fixing do you want to take a stab at
> > suggesting
> > > what parts might have survived?  A small quiz!
> > >
> > > Mike
> > > AC7MZ
> > >
> > >
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>
>
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