NanoVNA V2 / Forum

Note: this page is a mirror of
Click here to join and see most recent posts.

Power output

sweinreb 2021/06/04 23:13

I would like to use V2 to measure the 4 S parameters of a low noise amplifier.  To measure S11 the applied power must be <-10dBm  and to measure S21 the applied power must be <-30dBm.  What is the RF power applied to the device under test by V2?  I realize i can add an attenuator to reduce the applied power but this reduces the dynamic range.

Markus Schrodt 2021/06/05 14:41

What if you match the attenuation with the Gain of your LNA? I measured
S21 for a 60dB LNA with a 60dB attenuator using the NanoVNA without any

Am 2021-06-05 um 08:13 schrieb

Lynn Mears 2021/06/05 08:48

I think the power is adjustable. Here’s a link to the manual. Check the section entitled “setting sweep range and parameters”

Think we’ve met before. I was in grad school at UVA in the early 80s.

Weinreb, Sander 2021/06/05 16:25


The manual describes a power level setting of the source but then says v2 ignores those settings. I do know whether this means the calibration software ignore the power setting or whether the power control is not passed on to the signal source. I think the best step for me may be to buy the v2, measure the power output, and see what accuracy I can achieve through an S11 measurement that includes an attenuator.

Sandy Weinreb

Lynn Mears 2021/06/06 09:40

You’re right I missed that. So my V2 plus4 generates ~250 mV pk-pk into a 50 ohm load at 1 MHz. I can probably measure it at a few hundred MHz if desired but I suspect you may be looking well beyond what I can measure.

Lynn Mears

mce66 2021/06/06 09:10

For my Nano VNA V2.2 (Black and Gold) in Zero Span (CW mode) and ADF4350 TX Power 3, I get:
MHz   dBm
10   -8.9
100  -10.2
500   -8.9
1000  -9.5
2000 -10.5
3000 -11.9
4000 -11.8

Changing the ADF4350 TX Power in zero span mode does not have any effect immediately. Instead it takes effect *only when and if* you change the CW central freq (maybe this is a little bug). Outup  levels are reduced with respect to TX Level 3 of about 3 dB (TX level 2), 6 dB (TX Level 1), 8 dB (TX level 0). In scan mode (no zero span), the TX power configuration takes effect immediately.

So, above 140 MHZ, the out level is configurable between -10 dBm and -18 dBm. Below 140 MHz, the level is fixed at about -10 dBm.

Attached some SA figures.

Best Regards, Marco.

Weinreb, Sander 2021/06/06 17:34

Marco – Thanks, this is very helpful. - Sandy

To reply to this topic, join

View this thread on