Anders, the TL071 is not the right choice as it has a unity gain bandwidth of only 3MHz! You should use an OP with a unity gain bandwidth of ten times the wanted frequency at least (I guess 10MHz, so a 100MHz OP). Modern OPs are AD8045 (preferable), AD8099 (too fast and too good for this purpose;-), OPA847 and many others. The AD8045 can drive 70mA, so you could drive up to 15 outputs with 0dBm or up to 5 outputs with +10dBm simply by serial resistors (50 Ohm) from the OP output to each coaxconnector (+dc-block).
Joerg, DL2NI Am 17.12.2015 um 20:44 schrieb Anders Wallin: > First prototype assembled today, tested with 12 VDC SMPS wall-wart supply > and with 12 V lead-acid battery. > Compared against a SRS FS710 and a Symmetricom 6502 and John Ackermann's > 2007 plot: > http://www.anderswallin.net/2015/12/frequency-distribution-amplifier-first-tests/ > > What does the 6502 do differently? It is maybe 5 to 8 dBc/Hz better both in > PN and AM from around 1 kHz and out. > > My 'ultra-low-noise DC-supply' in the form of a lead-acid battery improves > things somewhat, but some spurs still remain: > http://www.anderswallin.net/wp-content/uploads/2015/12/2015-12-17_fda_spurs_and_comments.png > interpretations and explanations are welcome! > The board was not enclosed in a metal can for these tests. > > The regulator is an LP38798 > http://www.ti.com/lit/ds/symlink/lp38798.pdf > > > Anders > > > On Tue, Dec 1, 2015 at 12:54 AM, Bruce Griffiths <bruce.griffi...@xtra.co.nz >> wrote: >> Anders >> U101 only needs to have a gain of 1 at dc so replace R104 and R105 with a >> capacitor connected to ground. >> Adjust the other components of the gain determining network >> accordingly.Also the junction of the power supply divider R102 and R103 >> should be heavily capacitively bypassed to ground and a resistor placed >> between this junction and U101's noninverting input. >> >> Excess Sub Hz PN is usually due power supply noise or thermal fluctuations >> due to air currents/ convection. >> Most of the so called super regulator circuits should be more than quiet >> enough with an LM329 reference.A damped LCR filter at the input will >> improve the PSRR at switchmode output frequencies. >> >> Bruce >> >> >> >> On Tuesday, 1 December 2015 9:02 AM, Anders Wallin < >> anders.e.e.wal...@gmail.com> wrote: >> >> >> HI all, >> I need to build a few distribution amplifiers (>90% for 10MHz, sometimes >> maybe 5MHz) and instead of reinventing the wheel I decided to try to >> modernize the TADD-1 into an all (almost) SMD design. Here are some draft >> sketches: >> >> http://www.anderswallin.net/2015/11/frequency-distribution-amplifier-plans-a-k-a-smd-tadd-1/ >> >> Does this sound/look reasonable or crazy? >> Any suggestions for op-amps to try and/or compare to the AD8055? >> What causes the extra phase-noise below 1 Hz offset in John A's result: >> https://www.febo.com/pages/amplifier_phase_noise/amplifier_phase_noise.png >> >> Suggestions for a low noise DC-regulator circuit? The 12-24VDC supplied to >> this board will most likely come from a switched-mode PSU, so filtering of >> common-mode noise is mandatory. >> I found the TI LP38798 shown in the schematic by googling - if someone has >> a proven a measured design that would be a safer choice. In any case more >> filtering (e.g. ferriites) is probably a good idea. >> >> This design will be available on my blog or on github when it is done - if >> anyone is interested. >> >> Thanks, >> Anders >> _______________________________________________ >> 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. >> >> >> >> _______________________________________________ >> 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. >> > _______________________________________________ > 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. -- Dipl.Ing.(FH) Jörg Logemann Veilchenstraße 3 D-89150 Laichingen Germany Tel. +49 7333 922506 Mobil +49 171 2814359 Fax. +49 7333 922507 mail: joerg.logem...@t-online.de _______________________________________________ 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.
