Why not use an optocoupler as an isolation amplifier? - to the best of my knowledge it would provide infinite isolation. Cheers,.......................................Don Collie
----- Original Message ----- From: "Dr Bruce Griffiths" <[EMAIL PROTECTED]> To: "Discussion of precise time and frequency measurement" <[email protected]> Sent: Saturday, February 03, 2007 12:29 PM Subject: Re: [time-nuts] Stepping up the output of an OCXO > Ulrich Bangert wrote: >> Bruce and Didier, >> >> i had the opportunity to measure the output to output as well as the >> output to input isolation of a diy MAX477 based distribution amplifier >> very similar to the TADD-1 (but not identical). The output to output >> isolation was in the order of 75 dB while the output to input isolation >> was in the order of 90 dB. This is not too bad for this simple design >> and perhaps more than adequate for most of us time nuts. I have not been >> able to measure the increase in terms of noise figure but this statement >> must be read as: The increase in noise figure was less than the noise >> floor of my equipment. Nevertheless my statement of beliefs is the same >> as Bruce's one: A single transistor stage may be more easily optimized >> than a multi-transistor-design. >> >> Best regards >> Ulrich Bangert >> >> > > Ulrich > > Since the MAX477 has an input noise of around 5nV/rtHz at 10MHz compared > to around 1nV/rtHz for a low noise bipolar transistor, the MAX477 may be > expected to be have a phase noise floor of up to 14dB higher than that > of an optimised discrete transistor amplifier. This however may not be a > concern unless one has an OCXO with a phase noise floor approaching the > state of the art (-180dBc/Hz). > > There are wideband opamps with lower noise than the MAX477 available. > One could always use 4 MAX 477s inparallel to lower the phase noise > floor by about 6dB. > > Bruce > > _______________________________________________ > time-nuts mailing list > [email protected] > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.5.432 / Virus Database: 268.17.20/664 - Release Date: 2/2/2007 > 3:42 PM > > _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
