[TenTec] OT: two tone generator

[wa3fiy at radioadv.com]

Isn't an idling PSK 31 signal a two tone signal?   Seems to me it is.  Yes, the 
frequencies are pretty close together but I think it is two tones.  Modulate 
your transceiver into a dummy load and receive the signal on a well 
attenuated receiver and look a the signal.  I use Digipan 1.8.  Used to be 
free.  Not sure now but in any event, you can get an IMD reading on the 
PSK program.  Probably not well correlated with industry standard but it will 
give an idea of the transmitter chain linearity.   

In some tests I did a few years ago with a Pegasus as the transmitter and 
an Argosy as receiver, I got better than -30db IMD without alc action and 
just under -30 with alc action.  The test procedure and results are in the 
archives.  As a side note, I often use the waterfall for spectrum display 
feature of MMVARI for checking bandwidth, frequency response, agc action 
and various other measurements.  Pretty handy software to have around.

Just a thought.

73,

-Lee-

On 4 Sep 2008 at 13:45, Marinus Loewensteijn wrote:

> 
> 
> In my quest for sorting out my garbled SSB I looked at purchasing a two-tone generator. However in my computer I have a sound card so why not put that to some use?
> 
> I have found a product that has a 30 day trial which should be sufficient to test a whole rig.
> 
> It also has some other useful utilities like a spectrum analyzer. 
> 
> http://www.ymec.com/products/dssf3e
> 
> Perhaps something that can be usefull for others in their quest for repairing on a shoestring?
> 
> 73
> Marinus, ZL2ML
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