Enhancement request/question: VNA operation below 500 kHz

[glembler]

Hi Pavel,

I am investigating your VNA to measure and calibrate radios for our local museum of radio, California Historical Radio Society, https://www.californiahistoricalradio.com/. Most consumer AM radios have an intermediate frequency of 455 kHz, which is just below the VNA 500 kHz lower frequency limit. Do you have any plans to add support for VNA operation below 500 kHz?

Thanks,

Gary Embler, N6RTA gembler@google.com

[pavel-demin]

Hi Gary,

I'm not sure if I understand where you've found this 500 kHz limit.

As far as I know, my VNA application for Red Pitaya seems to work at much lower than 500 kHz frequencies.

For example, the second image in my notes about my VNA application shows a Smith chart for the frequencies from 1 kHz to 10 MHz. Those measurements were done with a very simple series fixture.

Best regards,

Pavel

[glembler]

Hi Pavel,

It's here: https://www.redpitaya.com/f172/vector-network-analyzer-module

HARDWARE SPECIFICATIONS

• freq. range 500k to 62MHz . . .

Thanks,

Gary

[pavel-demin]

Thanks for the clarification.

The 500 kHz limit is specific to the hardware sold by the Red Pitaya company. So, the question about this limit should be addressed to the Red Pitaya company.

A very simple series fixture can be assembled from a few resistors and SMA or BNC connectors and it'll work at low frequencies without any problem.

For example, here is a picture of my setup:

[pavel-demin]

Just found a couple of web pages showing very simple test fixtures:

http://www.scottyspectrumanalyzer.us/functioncrystal.html https://destevez.net/2017/09/measuring-a-mains-choke-with-hermes-lite-vna/

Other solutions can be found in the documents linked from my notes about the VNA application.

[glembler]

Thanks Pavel.

I sent a note to support@redpitaya.com asking about the limitation on the low-frequency operation of their VNA bridge module. I haven't heard any reply yet. Do you have a contact their who might know about it?

Gary

[glembler]

Hi Pavel,

Just checking again - Would you happen to have a contact at Red Pitaya who can answer questions about their VNA bridge module?

Thanks,

Gary

[pavel-demin]

If support@redpitaya.com doesn't answer, then I don't know who else can answer questions about the VNA bridge module.

[glembler]

I finally heard from Nick at Red Pitaya. He shared a few specifications for the VNA module. He also told me they are planning to do an improved version of the VNA module. He did not have specifications or a schedule for the new version.

On Mon, May 13, 2019 at 11:04 PM Pavel Demin notifications@github.com wrote:

If support@redpitaya.com doesn't answer, then I don't know who else can answer questions about the VNA bridge module.

— You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub https://github.com/pavel-demin/red-pitaya-notes/issues/836?email_source=notifications&email_token=AGDEILNOZRGZJS2AZXOPMM3PVJI7RA5CNFSM4HHNPCTKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGODVKLNYQ#issuecomment-492091106, or mute the thread https://github.com/notifications/unsubscribe-auth/AGDEILO2RBVKNRVTOVTGBVTPVJI7RANCNFSM4HHNPCTA .