On 5/28/06, Peter wrote: > > Excite DUT with white noise, convert output down to audio band using XO > and use spectrum analyzer running on PC audio card to visualise. > Schematic supplied. The nice part is that given a good mixer and LO this > whould work way up into microwave. Would work yes, but will be almost unuseless. The simple mixer must be replaced with an IQ one, else would be necessary two or three IF stages with all the problems. The biggest one will be the frequency fluctuation in the audio side and the limited bandwith or distortion. Also will be necessary a real VCO and not a white noise generator. There are many analyzers like this one on the web, the best one is using a tuner and claim to work ok till 2Ghz. I'm seeing every day how works a good spectrum analyzer (for it's 30 years old age) TEK492 and if that one can't be used for fast signal analyses, all analyzers having the same principle (unfortunately) can't. So depends what do you need. greetings, Vasile Finally an affordable solution for > filter and amplifier design for homebrew UHF and microwave ? > > http://www.qsl.net/7n3wvm/Fil_Meas.html > > Peter > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist