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Is the measurement frequency stable?
Dave
ZL3FJ

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Zack Widup via groups.io
Sent: Thursday, April 03, 2025 06:14
To: [email protected]
Subject: Re: [nanovna-users] Jittery , non steady readings

I have consistently had this problem measuring inductors, capacitors and
resistors. Just recently I measured a silver mica capacitor that was around
3400 pF. I measured at 475 kHz (630 meter amateur band). As I watched the
display, every time I got a new measurement I would see something like
3420.1
3416.3
3411.8
3418.6
3422.5
3424.2
etc.

I took the average of the measurements as the value. But I don't know why
this was happening. The same happens with resistors and inductors. I could
see the inductors as most likely to pick up radio signals. But I do not
live close to a radio station or any service that is transmitting near me
(as noted on a TinySA). I turned off my wifi and got the same results.

I use a right angle SMA connector with a wire about 3 inches long going
through the opening and soldered to the center pin contact, also another
wire about 3 inches long soldered to the SMA body. I solder the other ends
of the wires to the device under test.

Zack W9SZ

On Tue, Apr 1, 2025 at 2:51?PM kellogs via groups.io <mihai0226=
[email protected]> wrote:

Is it normal for the readings to fluctuate as much as 2-3 ohms ? As in
11+/-1.5 - j(70+/-1.5)

Dipole NMHA (antenna), balun, calibrated, two ferrites: one at the
balun and one at the VNA S11 port. No body / coax inadvertent
movements, everything taped down near the antenna.

Thanks

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