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From: Jeroen Belleman <jeroen@nospam.please>
Newsgroups: sci.electronics.design
Subject: Re: "Sampler??"
Date: Tue, 30 Jul 2024 23:39:07 +0200
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On 7/30/24 23:27, piglet wrote:
> Jeroen Belleman <jeroen@nospam.please> wrote:
>> On 7/30/24 19:46, Joe Gwinn 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
>>
>> If it's Agoston's, it's a genuine time-domain short-pulse sampler,
>> not an attenuator pick-off.
>>
>> Jeroen Belleman
>>
> 
> Doesn’t this predate Agoston’s work?
> 
> 

Looks like it does, indeed.

Jeroen Belleman