[Ground-station] Lime LMS8001a Companion Board

[Ron Economos]

I took another look at the spurs. They're not preset when the chip is in 
reset and appear as soon as the configuration is loaded (I'm using the 
supplied CMP_DOWNCONVERSION_CHD.ini file). They are not affected by VCO 
or PLL frequency. The "Smart Tune" function doesn't help.

They do track with the power amplifier gain setting. They also disappear 
if the power amplifier is bypassed (although the output is very low 
without the PA).

The LNA gain has no effect on the spurs.

Ron W6RZ

On 05/01/2018 03:11 PM, Mike Seguin via Ground-Station wrote:
> Hi Ron,
>
> Just finished a bit of testing here as well. I don't seem to see the 
> spurs you are seeing. (maybe try a different VCO Freq?)
>
> My test was at 5.8 GHz. On the LMS8001a I used 4.85 for VCO. Then 
> drove the IF with 950 MHz from an HP 8921A. Level was +6 dBm
>
> Spectrum analyzer was an Anritsu MS2721b 7 GHz unit.
>
> Reference level was -16.8 dBm. There was a 20 dB pad on the output of 
> the LMS8001a.
>
> 10 kHz marker shows a delta of -62.82 dBm in 1 kHz RBW, so for dBc/Hz 
> subtract 30 dB.
>
> The on-board 40 MHz reference is off a bit, but easy to lock down 
> using an external reference.
>
> I want to verify the measurements this coming weekend if I can at 
> W1GHZ's lab. Also check 10 GHz.
>
> Mike
>