Hi Warren
Cancel the comment about temperature and fridge testing. It was late at
night here & I was obviously more tired than I thought! What I should have
done was to recalibrate while cold. That will be a practical problem as the
vna gets covered in condensation as soon as it is out of the fridge.
The spikes in my photo are on a terminated ch1 and hop up and down.
Probably amplified noise as a result of the nano winding up the gain when
calibrated to compensate for low oscillator output. So the spikes I'm
seeing are in effect a measurement of a genuine dropoff in oscillator level.
73
Mike
On Mon, 26 Aug 2019, 00:35 Mike Brown via Groups.Io, <mbmail=
[email protected]> wrote:
Hi Warren
LOL. I'm not worried in the slightest given that the spikes on this vna are
40dB down. I am interested though.
The only possible impact I could see was if I was tuning up a filter and
happened to need it be a brick wall at 300 or 600 MHz. Seems pretty
unlikely to me.
The span in the photo started at 1.5MHz. I changed it to 500kHz and the
spikes were still present. I also put the vna in the fridge for 30min and
the spikes were still there. So much for the temperature theory! Maybe
that's a factor if the spikes are much worse.
73
Mike
