Path: ...!weretis.net!feeder8.news.weretis.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: piglet Newsgroups: sci.electronics.design Subject: Re: "Sampler??" Date: Tue, 30 Jul 2024 21:27:41 -0000 (UTC) Organization: A noiseless patient Spider Lines: 169 Message-ID: References: <72gfajl8ke966lsu54bpajpang9dvgmt63@4ax.com> <358iajpkaf41atvvnbq9no9p0uearvu8bk@4ax.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Injection-Date: Tue, 30 Jul 2024 23:27:41 +0200 (CEST) Injection-Info: dont-email.me; posting-host="28520715db5205ab431b3a814c2b4eef"; logging-data="1276237"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX191iIXufy4lntAUlo4DWgdy" User-Agent: NewsTap/5.5 (iPhone/iPod Touch) Cancel-Lock: sha1:KFjczsnInLoyhg3gh52Z4RGwpg8= sha1:cuBRjKzkhCMU+2I9Vvz6k9W6xiU= Bytes: 8859 Jeroen Belleman wrote: > On 7/30/24 19:46, Joe Gwinn wrote: >> On Tue, 30 Jul 2024 15:13:47 -0000 (UTC), Cursitor Doom >> wrote: >> >>> On Tue, 30 Jul 2024 11:01:17 -0400, Joe Gwinn wrote: >>> >>>> On Tue, 30 Jul 2024 14:51:10 GMT, Jan Panteltje >>>> wrote: >>>> >>>>> On a sunny day (Tue, 30 Jul 2024 11:20:47 -0000 (UTC)) it happened >>>>> Cursitor Doom wrote in >>>>> : >>>>> >>>>>> 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 wrote in >>>>>>> : >>>>>>> >>>>>>>> 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 wrote in >>>>>>>>> <72gfajl8ke966lsu54bpajpang9dvgmt63@4ax.com>: >>>>>>>>> >>>>>>>>>> On Mon, 29 Jul 2024 05:19:06 GMT, Jan Panteltje >>>>>>>>>> wrote: >>>>>>>>>> >>>>>>>>>>> On a sunny day (Sun, 28 Jul 2024 21:40:41 -0000 (UTC)) it happened >>>>>>>>>>> Cursitor Doom wrote in >>>>>>>>>>> : >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>>> 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. >> >> . >> >> 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? -- ========== REMAINDER OF ARTICLE TRUNCATED ==========