[hpsdr] ANAN-100D TX Spectrum

[Joe Martin K5SO]

Hi Jacques, 

Using an HP-8568B Spectrum Analyzer here looking at the output of Angelia while it transmits into a 50-ohm dummy load at 50.1 MHz I see no spurs greater than 70 dB below the carrier level in the frequency range that you mention.  

Sure, if you run the PA Gain setting for 6m band for maximum possible Tx output (i.e., absolute minimum PA Gain setting) and employ maximum drive level (38.8 on some versions of PowerSDR) you will see lots of spurs!  Don’t do that.  

I notice that in recent versions of PowerSDR there are new limits placed on the PA Gain settings that are permitted when ANAN-100D hardware is specified.  That’s probably a good idea, in my view, but it certainly doesn’t relieve the user from his responsibility for adjusting the settings for his particular rig to be optimum, of course.  

I recommend that since you have a spectrum analyzer at your disposal that you examine the output of your Angelia board while adjusting those two parameters, in particular.  By using the spectrum analyzer you have been using in tests while making the adjustments you can determine precisely how sensitive they are on your particular board in terms of producing absolutely clean Tx output.  

Indeed, "by-band" controls are provided in PowerSDR for PA Gain so that you may adjust your particular system to your desired/expected performance level on your particular rig.  I’m confident that if you experiment with your settings you’ll observe much better performance than what you initially reported.

Good luck!

73,  Joe K5SO




 1368496020.0