where to use a VNA when you need one?

I have been asking professors and amateur radio clubs, if there is a way I can use their VNA to test my own LNA design, but they wouldn't allow me to use their VNA. When you have a hobby to design your own RF equipment where do you go to test your own LNA prototype designs? I have also been told I could use a small VNA interface for a pretty cheap price at about S500: https://www.ebay.com/itm/1M-3GHz-Vec...oAAOSwETJaHARZ would this be just as accurate as a regular VNA? my LNA suppose to work at 2.4 GHz

You can use a diode probe and SDR receiver with a downconverter.

To achieve what? VNA is vector network Analysator and performs a vectorial (phase and magnitude) measurement of network parameters. Even for a scalar measurement with SDR, you'll need a least a test generator.

Oh, right. A noise generator should do fine if the money are tight. And you also probably need an attenuator so you don't fry SDR's input.

well i guess i can understand that. The VNA's cost between S20K and S250K, and to test an amplifier you have to DC bias it up. If DC leaks out, it can destroy the VNA. If you do not know how to handle the connectors and calibration kit, you also can destroy them.

If i were a home build sort of guy, i would get a VCO in the right frequency range, and use a potentiometer on the tuning port to manually sweep the output frequency.

I would use an Analog Devices LOG detector, with an attenuator pad in front of it, to measure the VCO output power, and then the amplifier output power as the VCO is swept in frequency, and deduce the gain from that.

https://www.digikey.com/product-deta...ALZ-ND/1543401

Have you worked on homemade built LNA prototypes? and have you used this method using a VCO with an attenuator to measure the frequency response, or do you secretly have a place you can go to measure your own prototypes on an actual VNA? What device would you use for measuring the output power and could this device be just as expensive?

If you need just once, rent it..

As far as I'm aware of, most of the cheap USB VNA boxes have acceptable quality. Some products have been previously discussed at Edaboard, but there are probably more competitive devices now.

Well, i have built systems that required high dynamic range swept frequency S21 measurements, and i used a Phase locked VCO and a log amp/ADC converter to do that measurement. The PLL i used was a Valon one. The Log amp an Analog devices one. And the ADC converter a Labjack one.
So the answer is YES.



i can understand your lament though. this is about the cheapest you can hope to get real test equipment for to do this test

https://www.ebay.com/p/Agilent-HP-87...934&opts=opick