> John, > > I'd say you nailed it. > > After some more testing, I can confirm that the limiter amp and the LPF > are the culprit. > I opened the box and plugged directly into the mixer LO port. > And, for the LPF, as a quick 'n dirty solution, I connected the <1 MHz > front panel output with the LNA input. > Now, at 10 dBm each into the mixer ports, I'm getting a noise floor of > <-145 dBc/Hz at 100 Hz and about -170 dBc/Hz at 10 kHz and above.
That's pretty aggressive for 10811s. The floor on those is usually around -165 dBc/Hz. How's your calibration process -- are you accounting for the 600 ohm output Z of the <1 MHz output port? It'll lose a few dB if you try to drive 50 ohms with it, and/or the filter response won't be correct. -- john, KE5FX _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
