Re: "Sampler??"

On Tue, 30 Jul 2024 18:13:36 -0400, Joe Gwinn <joegwinn@comcast.net>
wrote:

On Tue, 30 Jul 2024 13:31:20 -0700, john larkin
<jlarkin_highland_tech> wrote:
>

On Tue, 30 Jul 2024 13:46:06 -0400, Joe Gwinn <joegwinn@comcast.net>
wrote:
>

On Tue, 30 Jul 2024 15:13:47 -0000 (UTC), Cursitor Doom
<cd999666@notformail.com> wrote:
>

On Tue, 30 Jul 2024 11:01:17 -0400, Joe Gwinn wrote:
>

On Tue, 30 Jul 2024 14:51:10 GMT, Jan Panteltje <alien@comet.invalid>
wrote:
 

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...

 
HP always put the theory notes in the HP Journal, so I'd suggest
searching there for the HP8566B, in the issues around when the
instrument was first introduced.

>
This analyser is well over 30 years old, so whatever's gone wrong is most
likely age-related and wouldn't have come to light for many years.
Fortunately there's a lot of info out there - *if* you can find it!

>
On the lack of a schematic, I did dig into how it worked many years
ago, and as I recall it was based of some fancy abuse of a slotted
rectangular waveguide which supported various orthogonal modes - this
cannot be described by any lumped-parameter circuit.
>
Try this:
>
US4647795A, Travelling wave sampler, Agoston Agoston, Beaverton, Oreg.
Tektronix, Inc., Beaverton, Oreg. granted 3 March 1987.
>
.<https://patents.google.com/patent/US4647795A>
>
It does have schematics, in a manner of speaking.
>
Joe Gwinn

>
I have an old HP sampling plugin that uses a machined block slotline
structure. 3 GHz bandwidth as I recall.
>
<https://www.dropbox.com/scl/fo/3h4fvsfdh2youfd4kuolk/AIapB4g1x0BYRNXRIrAsrO8?rlkey=q5v7llkkk6yagr2w7h4c4kq8k&dl=0>
>
Agoston has a patent for a similar metal-block slotline sampler, but
as far as I know Tek never manufactured it. The SD-series samplers
were hybrids.
>
<https://www.dropbox.com/scl/fo/dnejszdktyc70se6frcdo/AM4vWFFsXPPF4Tw2ZeEm6m8?rlkey=xm82mhqn5mnrlv3l9j0pebj29&dl=0>

>
I recall these pictures.  I was wondering if HP copied the general
approach if not the patented design.  Or licence it.
>
Jeroen  correctly commented that "If it's Agoston's, it's a genuine
time-domain short-pulse sampler, not an attenuator pick-off."
>
Joe Gwinn

I recall that the founders of Tek and HP met and agreed to
cross-license their patents.