On Wed, 15 Jan 2020 21:05:43 -0800, Jeff Liebermann
wrote:


I just noticed some points you mentioned I forgot to cover in my
earlier post...

1. Network analyzer test Frequency

Shown in picture title for example 10Mhz.jpg means the VNA was set to
10Mhz.

2. SA (spectrum analyzer) horizontal MHz/div.

Full band mode so ~180Mhz/div.

3. SA vertical full scale, dBm per division, and dBm full scale.

No reliable info.

4. Whether you were misusing a scope probe (again) or feeding it
with 50 ohms.

Neither - sniffing with few turns of wire.

Also, any attenuators or couplers in the RF path.

Nope. Just the 40dB attenuation setting of the SA.

5. Did you remember to turn of the 1, 10, 50Mhz markers on the
HP8754A?

Yep, no markers.

Incidentally, you might want to ask in one of the HP test
equipment forums for what a working HP8754A RF output looks like on a
spectrum analyzer. I would not be surprised if the mess on your
screen is quite normal.

Good suggestion.

Incidentally, if you download and read the HP8754A service manual,
you'll find a large number of Performance Tests. Performed properly
in the manner specified, you should get a better idea if your network
analyzer is functioning as expected.

I do actually have the original physical hard-copy of the service
manual and was working my way through those performance tests when I
got side-tracked by something else whilst waiting for the required
phase-matched power splitter and some new terminations to arrive. I
really MUST get back to that as they have since turned up in the post.

I also need to try out some other poster's suggestion re sweeping the
VCO ramp with DC from batteries, too. So I have plenty to get on with
whilst you digest my replies, Jeff. :-/
--

No deal? No problem! :-D