[EMAIL PROTECTED] wrote: > Hi Bruce, > > I am pretty sure the Mixers' DC output is near zero when I am in lock, since > it only needs to compensate for the Opamps' offset voltage (very small). > > While the PLL is working on lock, the Mixer is slowly "homing-in" on the > lock voltage, and I don't really see that affecting the noise floor at all > (the > PLL loop bandwidth is about 1/2Hz, and thus below the analyzers' cut off, so > I am actually seeing measurements before the PLL is fully locked already). > > Something else is a bit awry here... > > bye, > Said > Said
What is the apparent noise at the mixer output when both inputs are driven in phase quadrature from the same source? i.e. use a quadrature hybrid or a suitable length of coax plus attenuators as required and disconnect the PLL. If its not a calculation/calibration error then it may be: 1) faulty/noisy mixer 2) Noisy PLL (EL2125 noise isnt specified at low frequencies its 22uA input bias current is fairly high for use as a PLL amplifier). 3) Noisy and/or oscillating preamp. 4) faulty preamp or PLL amplifier with output saturated so the power supply noise appears on its output. Bruce _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
