4 channel oscilloscopes - what are they good for?

[Cursitor Doom]

Hi all,

I've currently got 13 scopes of various types; most of 'em vintage. I
like it that way, old stuff. But it's far too many scopes in all honesty,
all taking up valuable space. One of the candidates for selling-off is a
4 channel Philips job (plain analogue). I can't remember ever having had
a need for examining 4 signals at once, but thought I'd better check with
the Panel first, just in case its a rare and valuable beast and nothing
else will do for some obscure application that may well crop up as soon
as I no longer have it around.
So... get rid or hang on?

[jurb...@gmail.com]

Only 13 ? Hell that ain't enough to scare a half a coulomb.

Only thing more than dual trace we got around here is the Tek 7000 series. Even on the 7603, the screen is barely big enough to actually measure anything with more than two traces. The 7834, it is even harder. But you don't use four traces to measure amplitude, it is for other things. Right now I got one of those other things but all that is on premises is dual trace.


We are in the prcess of scrutinizng a newly acquired HP 339A distortion analyser. At the moment there is a dual trace on the generator output and the secndary generator output. And then we wanted to see the "monitor" output of the HP just for kicks. So I had to break out another scope for that. Three traces required.

But this is THE FIRST TIME in my life I have ever had to do it.

When you go beyond two traces, you usually are looking at logic levels. Many scopes only have two full blown channels but add another couple that do not have the gain or the full blown attenuator and all that. They are more for looking at logic levels and so forth, not complex signal analysis. Well it is, but not analog signal analysis.

In such scopes it is important to be able to force the chopped mode at higher sweep speeds. Soetimes timing is everything and why else would you wwant to quad trace anything but to see the timing between pulses or whatever ? These scopes that autoatically make the choice for you, like it is chopped up to a certain sec/div and then switches to alternate piss me off. I would rather have a little bit of anomoly on the screen than to not be able to see the absolute timing between two pulses or signals or whatever.

But they do that because of a not so swell design. The chopper oscillator, though the speed neeeds to be controlled, but NOT be phase locked to anytihng, especially the incooing signal. But it does happen because it feeds through the power supply, ground or even the air. Bett design can prevent this, but that takes effort, and MONEY. More capcitors and decoupling resistors. More careful attention to the ground paths. It gets difficult and that is why cheaper scopes just don't let you chop at the higher sweep rates.

In other words, Elenco, Hotachi, whoever, they are saying "If you want a fucking Tektronix, buy a Tektronix". However, some Tektronix models might do it as well, I can't say because to do so I would have to be familiar with EVERY model they ever made, and the only guy who ever came close was Jim Yanik (NRA member). He used to post here and worked for Tektronix for about 350 years. This guy, you post like "I have a 7613 and it is... ... ..." describe the problem and he would come back with something like "Likely R456, but it could be a shorted C421 and that is a bitch to get to".

So, what is the model number, how much do you want for it and where the hell are you geographically ? I know someone who might be interested if it is a good deal.

That is if you can get by with only 12 scopes.

[Phil Hobbs]

Channels 3 and 4 are good for when you've blown up 1 and 2. ;)

(I have a 3-channel HP scope that I bought off eBay.)

Lots of times multiple channels are useful in looking at logic or serial
buses such as SPI (clock, data, chip select, DAC output).

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

[Jeff Liebermann]

On Sat, 15 Aug 2015 13:25:15 +0000 (UTC), Cursitor Doom
<cu...@notformail.com> wrote:

>I've currently got 13 scopes of various types; most of 'em vintage.

I just counted my collection at 15 (including those that are not
currently functional). I win.

>I like it that way, old stuff. But it's far too many scopes in all honesty,
>all taking up valuable space.

Yeah, I know the feeling. This is from 2011. Only one scope has
moved since the photo was taken:
<http://802.11junk.com/jeffl/crud/scopes-to-be-fixed.jpg>

>One of the candidates for selling-off is a
>4 channel Philips job (plain analogue). I can't remember ever having had
>a need for examining 4 signals at once, but thought I'd better check with
>the Panel first, just in case its a rare and valuable beast and nothing
>else will do for some obscure application that may well crop up as soon
>as I no longer have it around.

I've used a 4 channel scope as a makeshift digital logic analyzer.
Somewhat useful for catching glitches. The only time I really needed
4 channels was when I was working on a 3 channel TDOA (time difference
of arrival) radio direction finder. I displayed the various delays on
each channel, with the 4th used for probing the circuitry.

>So... get rid or hang on?

What model? What condition? Duz it all work?

(Scraped from eBay listings):
<http://www.theoscilloscopeshop.com/philips-oscilloscopes.html>
Also check the ebay sold items for your unspecified model scope.

Unless it's something valuable or useful, I suggest that you sell it.
I can't even give away my old analog scopes. The few I've given away
to starving students are usually returned after a few weeks with
comments like "too big" or "not enough features". Everyone seems to
want a (Rigol) DSO after they've played with one. For myself, I use
an oscilloscope program on my PC and an app on my tablet more often
than my various bench oscilloscopes.


--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

[Cursitor Doom]

On Sat, 15 Aug 2015 07:53:50 -0700, jurb6006 wrote:

> When you go beyond two traces, you usually are looking at logic levels.
> Many scopes only have two full blown channels but add another couple
> that do not have the gain or the full blown attenuator and all that.
> They are more for looking at logic levels and so forth, not complex
> signal analysis. Well it is, but not analog signal analysis.

Well, I had the case off this one a while back and all four channels
appear 'fully-featured' in that respect so far as I can see.

>
> In other words, Elenco, Hotachi, whoever, they are saying "If you want a
> fucking Tektronix, buy a Tektronix". However, some Tektronix models
> might do it as well, I can't say because to do so I would have to be
> familiar with EVERY model they ever made, and the only guy who ever came
> close was Jim Yanik (NRA member). He used to post here and worked for
> Tektronix for about 350 years. This guy, you post like "I have a 7613
> and it is... ... ..." describe the problem and he would come back with
> something like "Likely R456, but it could be a shorted C421 and that is
> a bitch to get to".

I remember Jim from s.e.d I think it was. I hope he's still alive and
kicking. A very useful fellow to have access to indeed.

> So, what is the model number, how much do you want for it and where the
> hell are you geographically ? I know someone who might be interested if
> it is a good deal.

It's the PM3264 and I'm in the UK. I'd like to avoid packaging and
international shipping if poss, so will try to off-load it locally before
seeking an overseas buyer. I don't think these old analogues fetch much
these days; 150 quid tops I would guess. Dunno what that is in your $$$$.

> That is if you can get by with only 12 scopes.

I want to get down to 3 *max* eventually, not counting the 2 rather
exotic analogue storage scopes I have which I want to be buried with. No
way am I selling those!

[Mark Zacharias]

"Cursitor Doom" <cu...@notformail.com> wrote in message
news:mqnpcq$9cq$2...@dont-email.me...

My most-used 'scope is a Tektronix 2246 4-channel.

Channels 1 and 2 are semi-permanently devoted to power amp measurements and
the 8-ohm loads stay there.
I will often use channels 3 and 4, since the vertical sensitivity is limited
to .1v or .5v switchable, to monitor the amp input.

For troubleshooting at the circuit level I generally use a Tek 465 on the
same bench.


Mark Z.

[Cursitor Doom]

On Sun, 16 Aug 2015 07:56:53 -0500, Mark Zacharias wrote:

> For troubleshooting at the circuit level I generally use a Tek 465 on
> the same bench.

I like the old Tek scopes, too. I have the 465 and a 475, one of which
will have to go. Logic says keep the 475, but one channel has gone low-
gain for some reason. If I can fix it I'll sell the 465 as it has a lower
bandwidth.
My favourite vintage Tek scope of all is my 466 analogue storage which is
in need of some serious troubleshooting. I'm going to be dealing with
getting that up and running early next year if all goes well.

[jurb...@gmail.com]

>"I remember Jim from s.e.d I think it was. I hope he's still alive and
>kicking. A very useful fellow to have access to indeed. "

A selfish attitude but I concur. As a person I think I would have gotten along with him. Signing posts "NRA member" is a good one. I know he is/was not a bleeding heart hoplophobic mamby pamby who thought the world is just alright and there are no crininals n shit. These motherfuckers who use every instance of an asshole going off and shooting people to further an agenda of disarming the public turn my fucking stomach.

The NRA is not exactly perfect, they have not been quite right lately. The NRA I remember touted safety courses, shooting training and stuff like that. They also sold insurance, which some hoplophobes want to require for gun owners. I mean for possible subrogation in case your guns are even stolen. My Uncle as a lifetime member and I can tell you that they are, or at least were, not what they're made out to be today. But the fact that he signed EVERY post like that makes it significant. Bottom line is if you are in a place where you are not allowed to have a gun you are in prison. And thart is possibly why there is less crime, people are born knowing they are subjects. We are entirely too arrogant for that here.

[Cursitor Doom]

On Sun, 16 Aug 2015 08:23:51 -0700, jurb6006 wrote:

[...]

Maybe that's why people are turning to Gun Owners of America?
Certainly when handguns were outlawed in the UK in 1996 or thereabouts,
gun crime went THROUGH THE ROOF.

[MJC]

In article <mqqm7r$d77$1...@dont-email.me>, cu...@notformail.com says...

>
> Maybe that's why people are turning to Gun Owners of America?
> Certainly when handguns were outlawed in the UK in 1996 or thereabouts,
> gun crime went THROUGH THE ROOF.

I'm a UK resident and unaware of either of the facts. Any references?

Mike.

[Cursitor Doom]

Nope. It's off-topic!

[jurb...@gmail.com]

No. Nobody is, well wait, there are people saying that. But I prefer facts. No I am a different wolf here. I belive that in this country, OK e are going to have gins.. I want so many guns that vriminals with guins don't have a real edge on anyone. Couple years ago this waffle house got robbed, err well attampted. a patron had a CCW and happened to be CCWing at the tie and blew the fucking N____S head the fuck off. His cousin gets on the TV and calls for better gun conttrol so her cous could still be alive. WhaT ? He was in there with a gun poionting it at people and cllecting up their money until someone with the balls and the means stopped him.

H?is cohort got away, so really I agrree with the bitch, the guy ho put her cousin where the fuck he belongs should have been able to kill the other guy right then, rather than have us support him or a decade or two.

Caught in the act. No jury is neded. I just watched you steal my whatever, rape or beat or rob or whatevr, there is no doubt. We do not need a team of detectives to place you a the scvene, this is where the coroners pick you up.

Ironically, I normally do not carry a gun and I really do not want to. But I think people should, so many that nobody will try anything. And people are brainwashedd, a gun is an equaliser. These son a bitches got nothing better to do in jail than work out. They spar and all that shit and become a weapon themselves.

They already HAVE a weapon. Long time ago I as like that. And being young and dumb I did some things I regret and really, I would kill me today. And maybe the world would be better off.

But if everyone has a gun, go ahead and try an armed robbery. You pull a gun and say "Gimme all your money" and 12 other people pull out guns and one of them shoots you. In my wworld then the barkeep says "Whoever shot that asshole has a free drink coming on the house, and could someone drag the carcass out of here ?".

Do this right and crime would be fucking zero in notime.

But the fact is there is money in cops and robbers. Same wirh the drug war. They don't fucking care if people get high, oothey just want to make money off of it. It is loke a tax. Dunno who knows this, but John Belushi's brother Jim Belushi was in some slightly more serious movies, among them pone called "The Palermo Connection".

In it he is a candidate fro mayor, presumptively of NYC. H?e was for the total legalisation of drugs. Thaat work explores for example polls. The questions asked and how the manipulation works. For example you can ask "Do you want your children to die of a drug overdose ?" or you can ask "Do you want your children to be killed in a drug raid ?". The piece really did explore some issues.

I have explored these societal issues to the point where it is difficult to have a discussion about it with normal people. So many are trained to believe that the government makes right. And wrong. What people do not seem to see is that the government exists to ake money for the rich. Even historical scholars sometimes have trouble seeing this, even knowing. Every military action is1 for money. You think this government cares about human rights ? [Nuclear biombs (like Iran right now) ? pFuck no. Iran has done NOTHING, while North Korea HAS nukes, HAS tested them and HAS thresatened to use nukes on the US as soon as they're able.

Why aren't we marching in there and pantsing them gooks ? I'll tell you why, because they have nothing we can sell. Iran is the focus because they have oil and aa fairly independent banking syste, the Rothschilds do not like that. Textile merchants my ass. Look it up.

And now look at the economies. Greece fell for the bullshit, but then they were bullshit in the first place. Now look at Iceland, they put people in jail for what bankers do here every fucking day. Look at Hungary, and this is played down but Hungary told the IMF to get the fuck out. I mean get your fucking offices out of the country.

More and more nations are bucking the petrobuck. The US put sanctions on Iran and guess what happened. They started selling oil directly to China, FOR GOLD. That is better money my friends, much better money than that which has to be propped up by quantitative easing.

Anyuway, by now you cvan see why I have a hgard time dicussing shit. You know, I want to talk current things and how and the why and all that, I simply do not have the time to start at the beginning and explain all about fracrtional reserve banking and how that made a few motherfuckers rich.

And last but not least, those motherfuckers who want you to give up your guns have no intention of givind up theirs. And that is a universal fact. Show me a fucking government without guns. Just one. You cannot, and that is the basis of the second amendment.

People seem to have troube here ::

"A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."

Now notice that it oes not say the right of the militia, the right of the government, the right of who the fuck knows, ;it says the right of the PEOPLE to keep and bear arms shall; not be infringed. And I got the arms definition down as well. Whatever this governemt can use on us we got the right to have rto use against them. Tjhat does not mean chemical and biological, and even this fucked up government wiol not nuke us, so that is not coverede. But Uzis n shit, yup. The same type of weapons they would use on us. That is arms.

I thought this through. Others watched TV, oveis, listened to music. Nope, I have little use for entertainment.

Now, I find people talk about Arabs/Muslims. That they want to kill everyone who is not Muslim. That is only partly true, it SAYS in Muslim/Islamic lands, not the whole fucking world. And let them have it. If all their Women escape fine, then they have no more children. Fuck, there's already a couple billion of them. That's pleenty. Meanwhile White Man is declining. And Jews. Know what ? You keep this shit up and then the next time you need some shit invented, call Achmed or whoever. Hey, I ak not saying they can't do it, but you know what ? You are going to find out because "we" are dieing off. Liberals have scathed at my take on humanity and even said they would not be happy untill all like me arte dead.

That is because I cal a spade a spade and I see the differences in the races. And other things as well. I see people vote their wallet all day long. The rich vote for less taxes nd the poor vote for more welfare.

Tell me I am wrong, and prove it. Restore my faith in the biomass. You cannot.

Anyway, my solution is to enjoy. Fuck it, I cannot help these assholes. So I will go out to the garage and roll one up.

[gregz]

I know I have looked at more than two channels. I had one scope with a
total of six channels. 2 plus 4 ch plugins. These were low bandwidth, so I
think it was more like looking at data logging events,

Greg

[Phil Hobbs]

The Tek 11801 series has four slots, each of which can take a
dual-channel plug-in. Plus there's an expansion unit (SM-11) that will
take 16 more plug-ins (multiple units can get you up to 136 channels).
So there's life after two-channel scopes. ;)