Oscilloscope - Which of these two?

[MTron]

I have an opportunity to pick up an analog scope from a local supplier, i was wondering if anyone could give me some feedback as to what they think. As a quick FYI, i probably wont be doing many things involving HF signals, mostly just analyzing audio equipment or power supplies i have built (non SMPS)

The first is a Kikusui COS-5100 100MHz scope, for $80 (Canadian). Here is the description the guy gave

"I tested the oscilloscope with a signal generator and the unit is in working condition. The display is very bright, crisp and clear. The buttons are a bit jumpy. One of the feet at the back was damage and two of the feet under the oscilloscope are missing, but the rest of the scope is generally in good cosmetic condition"
Here is a pic


The Second is a TEKTRONIX 2235 100MHz scope, this one is for $150 (again Canadian)

Description: "I tested the oscilloscope with a signal generator. Both of the channels pick up the signal and display a correct signal wave. No further testing was done. The CRT is very bright, crisp and clear. All the knobs and buttons are in good condition. There is some writing on the front of the scope that says" SCRAP/PARTS", but this item is actually a good working scope. There is no major damage or wearing on the body of the scope"
Pic 

There is a third i was looking at, from a place in the states (off eBay) but its 30 bucks +50 shipping + whatever duty+handling i have to pay when it crosses the border. The scope is a Hitachi V-509 50MHz, so unless its drastically superior, which of the top two would be a better buy?

I'm kind of leaning on the Kikusui, if only because i think it goes down to 500uV per division, and its cheaper, but if the Tek is superior i don't mind the cost.

Thoughts?

[tecman]

I would go for the TEK


Paul

[MTron]

I would go for the TEK


Paul

Any particular reason?

To he honest I'm not all that familiar with scopes, i have heard of Tektronix, but not Kikusui...but since im such a newb that really means nothing in my case. Is the Tek a better bet in terms of performance and reliability?

[saturation]

Tek is a top tier brand, probably the top.

Kikusui is a brand I worked with, its in line with Hitachi.  They are well known in Asia and some were brought to the USA as re-badged B&K Precision models.

On brand name alone Tek is better and roughly both being the same age, the Tek cost 2-3x more.

However, both are good for what you need, I would think the important item to consider which really works, and which will continue to work, and if it doesn't which is easier to fix?

Jap scopes typically have generic parts, they were mid level scopes for their time.  The only item unfixable is the CRT, if it blows.  The knobs and buttons being 'jumpy' is typical of old pots, wear on the wiper makes the connections intermittent, whereas the Tek are better made, and so old as it is, doesn't manifest the same dirty pot effect.

I never used the popular 2235 scope because it was out of our league, price wise.  I would download the repair manual for both scopes check the parts list, looking for any custom ICs.  That's the killer for repair.

[MTron]

hrmm, sounds like the general consensus is that the TEK is the way to go...if its a better value for money, and going to give me less issues, don't mind the cost, 150 is still pretty cheap for an oscilloscope, at least from what i have found over the past few weeks.

Anyone else want to chime in?

[alm]

I would probably prefer the Tek. Tek was the top brand of analog scopes (now it's just one of the three big brands), although the 2200 series was their economy line. People tend to be quite positive about the 2235, I think the reliability is pretty good. I would be somewhat worried about the parts/repair writing, it may have been fixed or a bad diagnosis, but it might also be a defect that the seller doesn't disclose (eg. it only works for a few minutes, but the seller took a picture immediately after power on, or it fails on some settings). It looks fine in the picture. One advantage with Tek is that there's a large amount of documentation. You can find a operations manual here, and can probably get a service manual or better scan of the operations manual for a few bucks from places like Artek Media (no relation, just a satisfied customer). If you have a problems, you can find help at the TekScopes group, and spare parts are available from places like Sphere and Qservice.

From a quick look, the Kikusui looks pretty good, too. Same 100MHz, dual time base. But finding documentation or help will be harder.

[saturation]

You can find documentation on Kikusui scopes here:

http://www.kikusuiamerica.com/man/?GROUP=COS&skip=21

BTW, perusing the Japanese site, they no longer make scopes.  Also the manual has a block diagram but not a full schematic. 

[Zad]

Go with the Tek scope any day of the week.

[EEVblog]

I had the 4 channel (12 Trace) version of that COS-5100, and it's a very good scope.
I'd be wary of the "scrap/parts" thing, someone wrote that on their for a reason! Intermittent perhaps?
Pot luck either way though.
Get both and sell the worst one back on Ebay!

Dave.

[MTron]

Well, i bought the Tektronix 2235!

Its works flawlessly as far as i can tell, i tried multiple inputs (signal generator at the place, my PC using a signal generator program, and the built in square wave 1khz 500mV signal output on the scope)

All the knobs and buttons work just fine as far as i can tell.

I look forward to really learning all the ins and outs of my first oscilloscope!

[alm]

Congratulations! If it works fine, this should be a very capable scope.

[MTron]

maybe the "SCRAP/PARTS" thing is written by a saloon guy who only cares about cosmetic and money and knows sh*t about osciloscope. just maybe

Perhaps, i had the scope on for over an hour so it at least got nice a warmed up, and there was narry a hiccup. Granted their could be problems with the scope and i just percieve them at normal operation, as this is my first scope, but as far as i can tell it works perfectly. When i get a chance ill grab a bunch of different things to test and see what the results are. I have a few unregulated DC supplies i have built that i would love to see the ripple voltage on.

[orbiter]

I'm always made up for people when I see that someone has got a bargain. I hope all goes well with the scope mate.

orb

[NiHaoMike]

Check the calibration. Maybe it was labeled that way because it needs recalibration, but the previous owner decided to buy a new one instead.

[gib0r]

Check the calibration. Maybe it was labeled that way because it needs recalibration, but the previous owner decided to buy a new one instead.

This. Gear often gets replaced and/or stored to be surplussed simply because they're out of calibration, even if there is physically nothing wrong with the unit. Enjoy the scope.