Ultra Low Noise Preamp, 40dB ,20Hz to 10Mhz

[DennisR]

I'm looking for a pre-build AC coupled 40db amplifier with very low noise. I would need a range between 20Hz to 10Mhz

I'd like to measure noise in the range of 100-500µV, but my oscilloscope noise floor is around 2mV.

The Picotest J2180A-20 looks promising, but in only has a 20dB gain. 
https://www.picotest.com/products_J2180A.html

[David Hess]

100 to 500 microvolts RMS over 10 MHz is 32 to 158 nV/SqrtHz which is not particularly demanding, and *worse* than some old 200 MHz oscilloscopes.

A Preamble DA1855 or LeCroy DA1855A does more than you need and might be suitable if you can find one.  Differential operation raises input noise by 40%, but also adds common mode rejection which removes noise.

https://w140.com/tekwiki/wiki/Preamble_DA1855

[sonpul]

If you described your tasks in more detail, perhaps someone will share their methods, experience and equipment used.

I'd like to measure noise in the range of 100-500µV, but my oscilloscope noise floor is around 2mV.

But the J2180A costs as much as a few new oscilloscopes to suit you. Maybe it makes sense for you to buy one and there is no problem?