[Elecraft] How to demo P3/K3?

[Geoffrey Mackenzie-Kennedy]

Don,

The main difficulty I believe with down-converting a band to "audio", and 
then up-converting back to RF to demonstrate the performance of the P3, 
could be the spurious products generated during each conversion, which might 
reflect badly on the true performance of the P3 if the products generated 
during each conversion resulted in spurs within the chosen span of the P3.

If the P3 included a record - playback scheme similar to that provided by 
the Perseus SDR, it would then be vey easy to demonstrate the performance of 
the P3. So far I have not found any "alien" spurs when using this feature of 
Perseus.

I have not yet investigated how this scheme is implemented in Perseus, but 
on occasion when using my Perseus either as a panadapter or as a stand-alone 
receiver I have recorded up to several hours worth of "band activity". Mind 
you the total size of the resulting files is massive!! The record-playback 
feature is also very useful when using Perseus as a spectrum analyzer during 
the development of circuitry, in that it provides a record of the effect of 
changes made.

FWIW

73,

Geoff
GM4ESD


Don Wilhelm wrote on Monday, August 09, 2010 8:19 PM

> You don't have to build that mixer to shift the ham band down to the
> audio range, a Softrock receiver will do that.
> For that matter, you don't need the I and Q channels, so any DC receiver
> without audio filtering after the mixer will do that job too.
> Turning it back into RF is the bigger problem.  You need an SSB
> generator followed by a wide band filter for that unless you want to
> tolerate the carrier and the opposite sideband as well.