Intermodulation after TIA-603c methode

[sophiante]

I am attempting to achieve IM spec. of 85dB after TIA-603. That is: 12dB SINAD +3dB reduced to 12dB again. Frequency is VHF band.

The two interferring signals must be 50KHz and 100KHz from center, but this close to the wanted signal makes the result of the measurement more like generator sideband noise than DUT receiver IM. At least I suspect that generator noise is why I hit a limit however good my receiver is (I think)
My generators are Rohde & Schwartz SML01 - not the very best noisewise.

Does anyone have similar experience?

 

[BigBoss]

Phase Noise @ 1GHz with 20kHz Off-set seems -128dBc ..That is not too bad.( 50 and 100 KHz off-sets are surely better)
IM product 85dBc shouldn't be disturbed from this Phase Noise.Have you ever checked the RBW of the SA ?? It shouldn't be high, if it's possible decrease as low as possible to able to see low level signals.

 

[sophiante]

You are right about the SG data but I am talking about PM receiver IM - No SA is involved only an audio distortion meter!