[Elecraft] Sound Generator / Audio Generator ??

Wed Aug 28 17:21:04 2002

David:

>I am just getting started on my K2 Kit.  I have seen
>many postings about a "sound generator" for testing.  I
>have a "BK 3001 Sine / Square Wave Audio Generator"
>laying around with my tools.  I picked it up a while ago
>but don't use it.  Is this the same thing as a "sound
>generator" and could I use it for testing my K2 kit.

I doubt it'll be of any use to you in this application.

Where we're talking about is not a 'sound' generator, but a 'noise' source 
which generates a broadband RF hash (somewhat like 'white noise') across 
the HF (RF) spectrum, rather than the audio spectrum.

Used in conjunction with the noise source, you'd use a software program 
named SPECTROGRAM, which is an AUDIO SPECTRUM analysis tool, that takes 
output from your SPKR or HEADPHONE jack, connected to the sound card of 
your PC and displays the audio on the PC monitor.

The noise source (you can also use 'band noise' from an empty spot on an 
active HF band as well) sends its broadband noise into the K2, it passes 
thru the xtal filters and the resulting audio is presented to Spectrogram 
as a 'block' of audio signal which you can then 'slide' through the 
passband of the K2 xtal filter until you have it centered precisely where 
you wish to have it located.

You repeat this step for each of your xtal filter settings (both for CW and 
SSB) and you have your filters aligned. It's not only easy, but it's also 
educational!

The Spectrogram software SELLS for $25, but the author offers a 'demo' 
version which is fully functional, BUT which only allows you to run it for 
10 minutes at a time. This may seem like a big problem, but once you get 
the feel for using Spectrogram, you'll find that you can probably align ALL 
of your filters in one 10-minute pass... though you'll probably have to 
make about 3 to 4 10-minutes passes while you first learn how to use it.

Spectrogram is available from:

   http://www.visualizationsoftware.com/gram.html

To find the Spectrogram (CW & SSB) Filter Alignment Articles, go to:

   http://www.elecraft.com/Apps/new_fil_docs/filter_apps.htm

   Once there, if the file you wish to access is a PDF (Acrobat Reader)
   file, RIGHT-CLICK on the link and when prompted to do so, SAVE the
   file to wherever on your HD you want it to go. If the link is NOT a
   a PDF, then LEFT-CLICK on the link and proceed.

You can find information about how to build a noise source at:

    http://www.elecraft.com/Apps/new_fil_docs/filter_apps.htm

At the site shown below, I have posted several examples of various 
construction methods for building a noise source, in addition the docs for 
the noise source itself:

     http://home.earthlink.net/~n0ss/download.html

If you wish to build the noise source, but want it as a 'kit', complete
with PC board,

    Don Brown (KD5NDB)            <[email protected]>
    19132 Falls Creek Drive
    Flint, Texas 75762

offers the a kit for $15 (US), including shipping in the US only.

Don's kit includes building instructions and all parts for the board.
You supply a box, switch, 9 volt battery and BNC connector.

To find the Spectrogram Filter Alignment Articles, go to:

   http://www.elecraft.com/Apps/new_fil_docs/filter_apps.htm

   Once there, if the file you wish to access is a PDF (Acrobat Reader)
   file, RIGHT-CLICK on the link and when prompted to do so, SAVE the
   file to wherever on your HD you want it to go. If the link is NOT a
   a PDF, then merely LEFT-CLICK on the link and proceed.

Spectrogram - CW Filters:
http://www.elecraft.com/Apps/new_fil_docs/k2_cw_gram.pdf

Spectrogram - SSB Filters:
http://www.elecraft.com/Apps/new_fil_docs/k2_ssb_gram.pdf

Hope this helps.

73,

Tom Hammond   N0SS