4 channel oscilloscopes - what are they good for?

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?
Reply to
Cursitor Doom
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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 anyth ing with more than two traces. The 7834, it is even harder. But you don't u se four traces to measure amplitude, it is for other things. Right now I go t 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 ana lyser. 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 o f the HP just for kicks. So I had to break out another scope for that. Thre e 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. Man y scopes only have two full blown channels but add another couple that do n ot have the gain or the full blown attenuator and all that. They are more f or 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 high er 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 s ee 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 anytih ng, especially the incooing signal. But it does happen because it feeds thr ough 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 fu cking 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 E VERY model they ever made, and the only guy who ever came close was Jim Yan ik (NRA member). He used to post here and worked for Tektronix for about 35

0 years. This guy, you post like "I have a 7613 and it is... ... ..." descr ibe the problem and he would come back with something like "Likely R456, bu t 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 hel l 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.

Reply to
jurb6006

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
Reply to
Phil Hobbs

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

Yeah, I know the feeling. This is from 2011. Only one scope has moved since the photo was taken:

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.

What model? What condition? Duz it all work?

(Scraped from eBay listings): 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     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558
Reply to
Jeff Liebermann

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.

Reply to
Cursitor Doom
[...]

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.

Reply to
Cursitor Doom

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

Mike.

Reply to
MJC

Nope. It's off-topic!

Reply to
Cursitor Doom

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

Reply to
gregz

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. ;)

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
Reply to
Phil Hobbs

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