Path: ...!3.eu.feeder.erje.net!feeder.erje.net!news2.arglkargh.de!news.mixmin.net!weretis.net!feeder8.news.weretis.net!reader5.news.weretis.net!news.solani.org!.POSTED!not-for-mail
From: Jan Panteltje <alien@comet.invalid>
Newsgroups: sci.electronics.design
Subject: Re: "Sampler??"
Date: Thu, 01 Aug 2024 05:13:43 GMT
Message-ID: <v8f5i7$kga6$1@solani.org>
References: <v85va8$19le$1@dont-email.me> <v86dsp$3n74$1@dont-email.me>	<v878oa$gbtu$1@solani.org> <72gfajl8ke966lsu54bpajpang9dvgmt63@4ax.com>	<v89sv9$hq1q$1@solani.org> <v8a9vr$v9r2$1@dont-email.me>	<v8afo4$i3b7$1@solani.org> <v8aiaf$10lqo$1@dont-email.me>	<v8auku$iedg$1@solani.org> <v8avr7$13368$1@dont-email.me>	<v8d563$jhaa$1@solani.org> <v8dios$1kovj$1@dont-email.me>
MIME-Version: 1.0
Content-Type: text/plain; ISO-8859-15
Content-Transfer-Encoding: 8bit
Injection-Date: Thu, 1 Aug 2024 05:13:44 -0000 (UTC)
Injection-Info: solani.org;
	logging-data="672070"; mail-complaints-to="abuse@news.solani.org"
User-Agent: NewsFleX-1.5.7.5 (Linux-5.15.32-v7l+)
Cancel-Lock: sha1:dNsAZCI1CEpyO1MnyT+RGT4DL4U=
X-Newsreader-location: NewsFleX-1.5.7.5 (c) 'LIGHTSPEED' off line news reader for the Linux platform
 NewsFleX homepage: http://www.panteltje.nl/panteltje/newsflex/ and ftp download ftp://sunsite.unc.edu/pub/linux/system/news/readers/ 
X-User-ID: eJwNyMEBADEEBMCWJFiUg9B/CXfzHGUctAkUoqvLEck1L6+gDii3OmGhnqtD7CSlY/9fRL99vGa3LRvjtPgAZoEWKw==
Bytes: 10286
Lines: 195

On a sunny day (Wed, 31 Jul 2024 14:46:52 -0000 (UTC)) it happened Cursitor
Doom <cd999666@notformail.com> wrote in <v8dios$1kovj$1@dont-email.me>:

>On Wed, 31 Jul 2024 10:54:58 GMT, Jan Panteltje wrote:
>
>> On a sunny day (Tue, 30 Jul 2024 15:11:35 -0000 (UTC)) it happened
>> Cursitor Doom <cd999666@notformail.com> wrote in
>> <v8avr7$13368$1@dont-email.me>:
>> 
>>>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 <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
>>>
>>>Yes, I have all of those and more. I think altogether there are 7 very
>>>large manuals for this analyser. However, I've not been able to find a
>>>single actual schematic which gives component level detail of what they
>>>call the "sampler" - and that's unusual, as they've given a great deal
>>>of attention to providing very full service details in all other
>>>respects.
>> 
>> Will read some of it and let you know what I come up with ..
>> 
>> OK have flipped through all circuit diagrams in the thing.
>> 
>> It looks to me like a heterodyne down converter followed by a narrow
>> filter IF stage tuned over the whole frequency range.
>> No sampling on the input signal at all.
>> Just a RF mixer.
>> PLLs in the tuned oscillator that are used to scan the band.
>> 
>> Like an old AM shortwave radio where you turn the big tuning knob really
>> fast mechanically to see the amplitude of each station on the cats eye
>> as you tune over the whole receive spectrum.
>> spectrum width set by the 450 kHz or so IF filter stages in those radio
>> days....
>> To get the IF narrow enough I did notice some crystal filter?, multi
>> stage RC filters?
>> Scanning the band takes time that way... horizontal deflection scope,
>> amplitude on vertical deflection scope..
>> Does it have a long persistence screen?
>> That way you can point at any small section of the input like long wave
>> / medium wave / shortwave in the old radios.
>> Also because I do not see any Fourier transform / computah /
>> computation..
>> 
>> That thing is from 1987? enough computah power back then for Fourier
>> transform?
>> 
>> I could be wrong though, more than a 1000 pages read in... lemme see...
>> an hour.
>> Need to sleep on it and look again.
>> Rest is just scope trace drive and power supplies..
>> Its all so easy:
>>  https://panteltje.nl/panteltje/scope_tv/index.html
>> HP should have added a teefee mode, but alas, analog teefee is dead in
>> most of the world these days.
>> 
>> This is more fun:
>>>> OTOH my 1.4 GHz RTL_SDR sticks cost 30 dollies($$) or so,
>>>>  https://www.ebay.com/p/22032165355?iid=335019807057
>> 
>> Use a Raspberry Pi or a PC ..
>> 
>> I remember when I build a frequency counter with nixy tubes and TTL and
>> 100 kHz crystal took it to work (tube days) it blew the guys away..
>> Then demoed it at the local ham group connected to the local oscillator
>> of a shortwave receiver Explained 'subtract the IF frequency from the
>> indicated frequency to get the real frequency'
>> Most radios have that now with nice LCD screens and PLL local
>> oscillators.... Or now even direct sampling like that SDR_RTL stuff.
>> 
>> 
>> I personally would dump the HP thing.. or maybe donate it to some
>> museum..
>
>Haha! No, neither of those things are going to happen, Jan. I'm still 
>suffering from PTSD at having to toss a Tek 555 into a dumpster 20 years 
>ago.
>Plus...... I've ordered *another* HP boat anchor to assist me to fix this 
>one! You can never have too many boat anchors (although of course, I 
>have). :)
========== REMAINDER OF ARTICLE TRUNCATED ==========