So many RF parts are spec'd for 9 KHz to xxx MHz. Even ones that are DC capable. ADRF5721 for example.
I guess that's because many spectrum analyzers and VNAs work down to
9K. But why is that?- posted
2 years ago
9 KHz
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- posted
2 years ago
8.3kHz is the lowest RF frequency allocated by the FCC. Maybe something to do with that.
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- posted
2 years ago
That's probably it. That makes lots of expensive sa's not work for audio.
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- posted
2 years ago
Local oscillator or synthesizer feedthru and noise. I can tune all of my ancient analog spectrum analyzers to DC, but all I see on the screen is local oscillator and synthesizer phase noise.
"Low frequencies on Spectrum Analyzers"
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Also, the input coupling capacitor for 50 ohms at 9KHz would be about
0.35uF (or larger), which is physically large for a non-polarized capacitor that is expected to also work over several decades of higher frequencies.- Vote on answer
- posted
2 years ago
That's news to me! And I've had a few.... Next on the bench here will be a huge HP audio SA. I'll get that back in spec and bung it on Ebay for some audiophool to pay a shit-ton of money for. :)
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- posted
2 years ago
Am 13.07.21 um 19:29 schrieb Cursitor Doom:
Spectrum analyzers intended for compliance tests do not need to work below 9 KHz, so they are specc'ed that way.
My SNA-33 does 20 Hz - 26.5 GHz with 1 Hz resolution. Unfortunately it is currently ill. :-(
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- posted
2 years ago
Repairable? Or does it have some problematic parts? I'm guessing the latter. That's the main obstacle for anything built after about 1990.