Beware of cheap underperforming clones

As of 2022 there are many badly performing clones on the market. V2/3GHz NanoVNA uses parts like ADF4350 and AD8342 which are costly and clones have been cutting costs by using salvaged or reject parts.

See official store and look for V2 Plus4/V2 Plus4 Pro versions only to avoid getting a bad clone. We have stopped selling V2.2 versions since October 2020, so all V2 hardware that are not Plus or Plus4 are not made by us and we can not guarantee performance.

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S21 oddity while measuring an LNA

sdturne 2020/08/16 16:30

Hi,

Today, I wanted to look at this mystery Avantek branded LNA that I have sitting around. It's specified for 5-1000 MHz and is supposed to be nominally 15 dB gain over this frequency range. However, the NanoVNA V2 is acting like there is a big step in S21 gain at about 125 MHz (see screenshot of NanoVNA saver in attachments). I also included the Touchstone file (second attachment) exported from the software. I have a high quality Narda 6 dB pad on Port 1, and I have entered this into the sweep settings of the software.

It is interesting to note that this step in S21 gain apparently does not exist. There is no sudden step in gain in this area when the same amplifier is fed a CW signal from an RF signal generator and the output is observed on my 8566B.

Any idea what might be going on?

Thanks,

Sean

avantek_amplifier.PNG
OwO 2020/08/17 11:48

It looks like ADC saturation, the gain of the amplifier looks to be
around 15dB so try a 15 or 20dB attenuator on port 2.

On 17/08/2020 07:30, sdturne@q.com wrote:

- Show quoted text -
sdturne 2020/08/17 20:07

On Sun, Aug 16, 2020 at 08:48 PM, OwO wrote:

>
> looks like ADC saturation, the gain of the amplifier looks to be around
> 15dB so try a 15 or 20dB attenuator on port 2.

Good call; tried with a 20 dB pad and all is well.

Sean

avantek_amplifier_20dB_port1.PNG

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