Keysight EXA Signal Analyzer / Spectrum Analyzer Review, Teardown & Experiments

[G0HZU]

At 26:09 does it say WHY ME in via holes? Look above the P3 pattern and turn it 90 degrees?

It looks like someone has written WHY ME  with the via holes

[c4757p]

It looks like someone has written WHY ME  with the via holes

[KE5FX]

At 26:09 does it say WHY ME in via holes? Look above the P3 pattern and turn it 90 degrees?

It looks like someone has written WHY ME  with the via holes

That was added by the board house.     There wasn't enough room for, "Yo, dawg, we heard you like vias, so we put vias in your vias so you can ground your vias."

[Hugoneus]

One other comment I have is wrt 9:15 onwards. The mixer #2 that is used across 3.6-17GHz won't be a subharmonic mixer. This mixer is circled in red below. The other two mixers above it (#3 and #4) are harmonic mixers.
Mixer #2 does require 'double' the LO frequency but this doubling is done external to the mixer. So this mixer is a fundamental mixer rather than harmonic. This LO doubler can be seen below circled in dark blue.

I never said all the mixers were sub-harmonic mixers.

You seemed a bit confused as to the role of the (seemingly unused?) 17GHz filter contained withiin the light blue circle below. These two lowpass filters are used to clean up the output spectrum of the doubler. The ideal filter to have here would be a tunable/LO_tracking filter but Keysight have used a pair of lowpass filters at Fc 14GHz and 17GHz. So although the block diagram doesn't show this, the analyser will dynamically swap between these two filters as the LO is swept within a range. You can't get adequate spurious suppression with just one filter so I think it will swap dynamically between these two filters as required

I am not confused about the role of the filters, in fact I explained exactly what their purpose was. I pointed out that in none of the signal paths for different frequency paths does the 17GHz filter seems to be used in the block diagram. I also said this is likely an error on the block diagram.

[Hugoneus]

At 26:09 does it say WHY ME in via holes? Look above the P3 pattern and turn it 90 degrees?

It looks like someone has written WHY ME  with the via holes

Haha! Brilliant.

[G0HZU]

I never said all the mixers were sub-harmonic mixers.

There are a lot of mixers but the bit I was referring to starts from about 8:45 onwards. Of those three mixers labelled as #2, #3 and #4 on the block diagram, I think that only #3 and #4 are the (sub)harmonic type. But your commentary suggests that they are all subharmonic.

Also your commentary from 9:18 indicates that you think that you were pretty certain that mixer #2 (17GHz) was subharmonic.

I think this mixer is fundamental mode only. I think that it is a fundamental mixer when used as the second mixer on the 9kHz-3.6GHz low band range and also when it is used as the first mixer on the 3.6-17.1GHz range. I guess it's no big deal either way and it doesn't really detract from the video...

[G0HZU]

At 26:09 does it say WHY ME in via holes? Look above the P3 pattern and turn it 90 degrees?

It looks like someone has written WHY ME  with the via holes

That was added by the board house.     There wasn't enough room for, "Yo, dawg, we heard you like vias, so we put vias in your vias so you can ground your vias."

Yes, I wonder if P3 refers to a code for a specific via type on the drill drawing for this PCB. So the 'love P3' and 'WHY ME' is a dig at the RF design team from the unfortunate PCB draughtsman who had to place all those (P3?) via holes... 

[Hugoneus]

Attached is the PDF of the test setup per request. I will also add it to the site.