Thank you all for the comments, articles and numbers on real opamp setups - I find it really helpful.
On 24 November 2013 17:29, Bob Camp <[email protected]> wrote: > Hi > > Switch over to 60Hz power and I’ll bet those spurs move to 120Hz. > > Anything with a rectifier in it can produce (but may not produce) nasty > current spikes at 2X the line frequency. What you are seeing is magnetic > coupling of those narrow pulses. Is it coming from the switcher in the amp > or something else? Hard to tell without some fancy line isolation equipment. > > Bob > > On Nov 24, 2013, at 8:20 AM, Ulrich Bangert <[email protected]> > wrote: > > > Stephan, > > > > I made me a DIY distribution amplifier based on AD8007s. Mine achieves a > > typical >90 dB output to output isolation and a typical >115 dB (any) > output > > to input isolation @ 10 MHz. The phase noise starts abt. -140 dBc @ 1 Hz. > > The wideband phase noise floor is abt. -160 dbc and is reached at abt 4 > kHz. > > > > > > There are some spurs at multiples of 100 Hz of which the biggest is -114 > dBc > > @ 100 Hz. > > > > The power supply uses a switcher @ 80 kHz followed by a "voltage refiner > > circuit". I would have expected to see the switcher frequency in the > phase > > noise diagram but I don't notice anything. Instead I see these 100 Hz > based > > spurs. I have currently no idea whether the 100 Hz is really in the > output > > voltage or whether it couples magnetically from the switcher's primary > > circuit into the T1-1T transformers that I use at the input and the > outputs > > of the amp. > > > > Phase noise Measuerements were done with a TimPod 5330A and level > > measurements were done with an ANRITSU MS2601B spectrum analyser. High > > quality double shielded cables were used in the measurements. > > > > Best regards > > Ulrich > > > >> -----Ursprungliche Nachricht----- > >> Von: [email protected] > >> [mailto:[email protected]] Im Auftrag von Stephan Sandenbergh > >> Gesendet: Donnerstag, 21. November 2013 14:47 > >> An: Discussion of precise time and frequency measurement > >> Betreff: [time-nuts] Isolation achieved by opamp based isoamp? > >> > >> > >> Hi, > >> > >> I'm curious about the level of isolation that is achieved by > >> an opamp based isoamp. I'm referring to ones described here > >> on Bruce Griffiths' page: > >> http://www.ko4bb.com/~bruce/IsolationAmplifiers.html > >> > >> Anyone has a number for this? > >> > >> I've tried googling it, but the results are mostly filled > >> with the other kind of iso amplifier where isolation refers > >> to galvanic isolation. > >> > >> Regards, > >> > >> Stephan. > >> _______________________________________________ > >> 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. > > > > _______________________________________________ > > 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. > > _______________________________________________ > 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. > _______________________________________________ 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.
