Re: [time-nuts] DIY VNA design, directional coupler

Alexander wrote: there is a current mode feedback device [which does not follows the gain bandwidth product role ] and has 1000V/usec rise time 92dB THD at 30MHz 3nV/rtHz noise Yeah, but look at its 1/f input voltage noise corner -- it's at 2 or 3 MHz!!! So the baseband input noise density

Re: [time-nuts] DIY VNA design, directional coupler

there is a current mode feedback device [which does not follows the gain bandwidth product role ] and has 1000V/usec rise time 92dB THD at 30MHz 3nV/rtHz noise, see here http://www.ti.com/lit/ds/symlink/ths4271.pdf, I used it as a medical color Doppler application Guanella's choke and

Re: [time-nuts] DIY VNA design, directional coupler

On Sun, 21 Aug 2016 10:04:10 -0700 Alex Pummer wrote: > directional coupler/circulator could be made with high bandwidth [ up to > 1GHz ] operational amplifiers, that circulator will work from DC.. While this is a valid option, it would then become the element in the system

Re: [time-nuts] DIY VNA design, directional coupler

directional coupler/circulator could be made with high bandwidth [ up to 1GHz ] operational amplifiers, that circulator will work from DC.. driving A/D converter input asymmetrically; drive trough a Guanella-choke, but match the output of the choke 73 Alex On 8/21/2016 3:21 AM, Attila