Folks,
My original two tone test generator used op. amps., with light bulbs
for amplitude stabilisation. It was always trouble and I consigned
it to the 'recycle for bits' bin some years back.
There's been some talk on this reflector about three tone testing as
an alternative to the 'aaaarrrrrrgggghhhhhh' method. Those, like me,
trying to find a use for an ever growing pile of old PCs, may care to
check out 'Spectrum Lab' software, by DL4YHF:
http://people.freenet.de/dl4yhf/spectra1.html
This PC-based test tone generator I have found particularly FB for
two tone testing (no more distorted, light bulb-based junk for me!)
and, as I recall, the software has three independently programmable
tone generators. For two tone testing, I put one tone down the left
output from the PC sound card and one down the right. I then fine
balance the tone levels with a pot between left and right legs, prior
to feeding to the TX.
I'd be interested to hear of any results from those that have tried
three tone tests. On paper, a three tone test, with a suitable low
frequency component as one of the tones, should give a more
real-world result, but I wonder how 'user friendly' the results of a
three tone test might be? Manufacturers of amateur kit are already
in the habit of quoting TX IMD against PEP, rather than against each
tone (or cooking the books, if you wish) - I doubt they would welcome
any move that made their equipment performance figures look even worse!
Regards.
Mark.
-----------------------------------------
At 02:56 30/09/2005, you wrote:
>QST,
> I've just added a description of my excessive Two-Tone Test
> Generator to my website.
>
>http://wc6w.50webs.com/wc6wtest/index.html?fr20.html
>
> Enough data is provided to duplicate the thingy if you are so
> inclined... or be forewarned against it. :-)
>
>73 & Good evening,
> Marv WC6W
>
>
>
>
>
>
>
>*
>
>
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*******************************************
Mark Hill - G4FPH
E-mail: g4fph@mjha.co.uk
Current web pages at: www.qsl.net/g4fph
Old web pages at: www.g4fph.freeserve.co.uk
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