开云体育

For filters, not active devices (!!), one can amplify the BB noise to the point where a good SA is able to display (maybe barely) 100 dB of dynamic range.? All my "professional" SAs are capable of? 100 dB of on-screen range.? I don't use the TINYSAs for aligning cavities.? That's a job for the HP8753C or equivalent.?

Lot's of gain from the Zener, if that is what's used, is required.?

Here is a link to the Elecraft BB (500 MHz) noise source (a number of others are available on Amazon and epay):

? ? ?

These are specified at 35 dB of excell noise from 100 kHz through 500 MHz, depending on the characteristics of the noise diode.??

I just checked my calibrated noise source (25 dB of excess noise) through the HP 8447D BB amplifier into the 8568 SA.? The source is attenuated down to 20 dB excess noise for other purposes.? With that combination, I observed 20 dB of excess noise.? Therefore, an additional gain of roughly 80 dB would be required to hit the top, 100 dB above the bottom of the display, to yield 100 dB of dynamic range.? Agreed, this is a lot of gain, but easily obtained with MMICs or (Amazon or epay) BB amplifiers.

Note, my direct conversion receiver I use for analyzing ionospheric scattering of the WWV transmitters includes a BB 75 dB gain block (and filters) home brewed from MiniCircuits MMICs. ? Only three MMICs are used. ? I'm only 30 or so miles south of Wellington so I receive both scattered and GW signals from Wellington.? Gain is easy so long as the builder is aware of best engineering practices addressing isolation between stages.?

Dave - W?LEV?