Re: "Sampler??"

On a sunny day (Tue, 30 Jul 2024 11:20:47 -0000 (UTC)) it happened Cursitor
Doom <cd999666@notformail.com> wrote in <v8aiaf$10lqo$1@dont-email.me>:

On Tue, 30 Jul 2024 10:36:51 GMT, Jan Panteltje wrote:
>

On a sunny day (Tue, 30 Jul 2024 08:58:35 -0000 (UTC)) it happened
Cursitor Doom <cd999666@notformail.com> wrote in
<v8a9vr$v9r2$1@dont-email.me>:
 

On Tue, 30 Jul 2024 05:16:24 GMT, Jan Panteltje wrote:
>

On a sunny day (Mon, 29 Jul 2024 09:29:04 -0700) it happened john
larkin <jlarkin_highland_tech> wrote in
<72gfajl8ke966lsu54bpajpang9dvgmt63@4ax.com>:
 

On Mon, 29 Jul 2024 05:19:06 GMT, Jan Panteltje <alien@comet.invalid>
wrote:
>

On a sunny day (Sun, 28 Jul 2024 21:40:41 -0000 (UTC)) it happened
Cursitor Doom <cd999666@notformail.com> wrote in
<v86dsp$3n74$1@dont-email.me>:
>
>

I still can't see where the 'sampling' bit comes into it.
AFAICT, there's are two signals into this thing and one signal out.
The signal from the LHS is passed through a very fast diode which
generates harmonics from that fundamental. The signal from the RHS
is unmodified and mixed with the desired harmonic to give the
necessary output signal which is then filtered to get rid of the
unwanted mixing products. If that's all correct, as I believe it is,
where does any *sampling* come into it?

>
A 'sampler' is fact a non-linear mixer.

>
In the audio world, a "mixer" is a linear summer.
>
In RF, a mixer is usually a multiplier, typically a 4-quadrant diode
thing or a Gilbert cell type circuit. Or a 2-quadrant thing like a
pentode. Or even a single diode. All do some flavor of multiplying.
>
Some mixers inherently multiply a signal by a square wave, which
resembles other multiplier-type things once you lowpass filter the
output. That's a "synchronous detector", which we usually do in an
FPGA.
>
A sampler is a signal multiplier too.
>
These are all variations on the basic idea of multiplying two signals.

 
A the word 'mixer' in RF is not the same as a multiplier,,
Multipliers are like harmonic generating stages say you have a 1 MHz
distorted sine wave and then a second stage tuned at 3 MHz,.. turned
to third harmonic.
 
mamamatical speaking RF mixing is indeed multiplication.
 
Like Shakepierce once said:
 "What's in a name..." CocaCola wihout coke

>
I think in this context, HP is using the term "sampler" to mean
something which 'sniffs' a small amount of a signal for testing
purposes. Like a few turns of wire around a transmission line will
'sniff' a small sample of what's going on in the line.
Where I went wrong was rigidly thinking HP meant 'sampling' in the
manner a sampling oscilloscope works. That's what threw me. I tend to
interpret things very literally. :(

 
Would be nice to see a real circuit diagram of that thing.
What is the model / type number?
I am curious.
So far I have been able to find circuits for most stuff I came across
with google.

>
It's the HP8566B - a very well known lab-grade analyser of the day which
many RF designers still use. There is a *ton* of service info on this
model online. However, I have not been able to see a *proper* schematic
for the "sampler" in the A11A5 board which is where the issue is.

OK, thank you, I will google a bit..
I got the user manual now:
 https://elektrotanya.com/hp-8566b_spectrum_analyzer_100hz-2.5ghz_2-22ghz_usr-programming_1984_sm.pdf/download.html#dl
Then trouble shooting manual part 1
 https://xdevs.com/doc/HP_Agilent_Keysight/HP%208566B%20Troubleshooting%20&%20Repair%20Vol.%201.pdf
Seems to have at least some circuits (just a quick look)
and part 2
 https://xdevs.com/doc/HP_Agilent_Keysight/HP%208566B,%208568B%20Troubleshooting%20&%20Repair%20Vol.%202.pdf
also has some circuits
I will have a look at the hundreds of pages, will take some time.
I presume you have these?
Took 10 seconds to find with google

OTOH my 1.4 GHz RTL_SDR sticks cost 30 dollies($$) or so,
 https://www.ebay.com/p/22032165355?iid=335019807057
I can use a 5 dollies($$) satellite LNB as down mixer to go from 10 to 12 GHz to say 1 GHz (modified a LNB for xtal locked to Rubidium reference)
Also build a small downmixer so it can see 2.4 GHz too
Plenty free spectral display programs online for it,
I wrote my own:
 https://panteltje.nl/panteltje/xpsa/index.html
it also has an 'harmonic' button to look for the next harmonic when you select a carrier...
The latest version has some more stuff and runs on Raspberry Pi..
The RTL_SDR sticks can even receive GPS signals...
 https://panteltje.nl/pub/run_50_outside_2728000.gif
 uses this guys software<;
  http://michelebavaro.blogspot.nl/2012/04/spring-news-in-gnss-and-sdr-domain.html

For 100 Hz to 20 kHz a PC soundcard or maybe USB audio stick (as I use for my Raspberry)
and there are several audio programs with spectrum display

There are so many possibilities...