Or use 1Audio's method -- you can even use a 100 ohm potentiometer on the input. Measure at a convenient frequency like 1kHz and note the RMS value, insert the potentiometer onto the input and adjust until the reading is 1.41X the shorted measurement. Take the resistance value, Boltzman's constant etc and le voila! 15.3 Ohms is 500pV/RtHz at room temperature.
Yes, that part of calibration is clear. My question was purely related to REW preamp scaling. I had some doubts about using the ""FS sine Vrms" box for this since REW rounds the entered number (e.g. 0.00396 becomes 0.004). However I believe REW internally still uses the exact entered number.
Jan - I have a fully build board you can play with. As I have posted previously it is not fully functional (non-linear response below 1 kHz), but maybe you can fix this 
I can also send along some matched BF862 if you should want to build a new one.
Let me know if you are interested.
Cheers,
Nic
I can also send along some matched BF862 if you should want to build a new one.
Let me know if you are interested.
Cheers,
Nic
Jan,
2SK3557 seems to be a good replacement:
:: JFET low noise amplifier exploration
If you're interested, I could send you ten BF862 from the original production.
Regards,
Braca
2SK3557 seems to be a good replacement:
:: JFET low noise amplifier exploration
If you're interested, I could send you ten BF862 from the original production.
Regards,
Braca
For JLBPCB it may actually be cheaper to share the design in their system and us order boards directly since their shipping and PCB prices are so low. Sending PCB's from EU to USA is more expensive than it should be. I just ordered 10 boards from JLBPCB that came to $25 delivered.
Even cheaper to Europe. I got these just before XMAS. 10 pcs. for €14.20 all included.
There was also a UHF amplifier on that design and some test structures that I cut off
with the circular saw. ( Guess what it is
16*CPH3910, gain & BW switched cold with relays. )
They send the production of a day for Europe to an agent of theirs who is in Germany.
He does all the customs and he forwards the small packages from the big box by inland mail.
Cheers, Gerhard
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I knew that would come!
Yes. I did commercial GHz stuff over the summer, but during the xmas shutdown there was more time available than planned. There were only minor changes. Probably the last
iteration.
I'm also building a 432 MHz rig for EME. That's what the other half of the board was for.
We measured a noise factor of 0.3 dB for the SKY 67150 evaluation board on 432.
I only get 0.6 dB no matter what I do. I even swapped components with the eval board.
Mine is FR4, the eval is Rogers 4350. The only difference that stays. Can't believe
that it is that. Between the SMA and the FET gate is just 2*0603, 20 pF and 22 nH.
No resonance, nothing.
Cheers, Gerhard
Yes. I did commercial GHz stuff over the summer, but during the xmas shutdown there was more time available than planned. There were only minor changes. Probably the last
iteration.
I'm also building a 432 MHz rig for EME. That's what the other half of the board was for.
We measured a noise factor of 0.3 dB for the SKY 67150 evaluation board on 432.
I only get 0.6 dB no matter what I do. I even swapped components with the eval board.
Mine is FR4, the eval is Rogers 4350. The only difference that stays. Can't believe
that it is that. Between the SMA and the FET gate is just 2*0603, 20 pF and 22 nH.
No resonance, nothing.
Cheers, Gerhard