On 2020-01-12 19:18, Cursitor Doom wrote:
On Sun, 12 Jan 2020 17:17:04 -0500, Phil Hobbs
wrote:

Frequency domain glitch? You mean a discrete spur? A glitch is a
transient time-domain animal.

I could have put it better I guess. What I mean is I'm seeing thin
spikes in the RF output spectrum of the VNA at other frequencies
than the desired one.

Which is a discrete spur. Gotcha.

I'm guessing these spikes are the result of unwanted transient
voltage spikes present on the DC VCO control voltage which sweeps the
RF output frequency from 4Mhz through to 1.3Ghz.

If there's a forest of them, spaced at equal intervals, they could be
coming from a periodic time-domain source.


A DSO can save a single instance, or (with averaging) ignore the
noise and asynchronous background and just reproduce the glitch
itself.

Well, Jeff has posted some advice for me on that aspect which I
intend to try out tomorrow using my Tek DSO which is probably much
better suited to the task than the analogue one I've hithertofore
been using..

Yeah, I'm fonder of analog scopes than JL is, but my beautiful Tek 2467
hasn't been used in quite awhile, whereas I use the 1180x, TDS 694C and
TDS 784As most days that I'm in the lab. For manual driving, the 2467
has the best triggering of the lot, but it's very hard to beat a DSO for
general use.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com