Time to bite the bullet...

[Bruciep07]

... And buy an oscilloscope, wondering what everyone's thoughts are on what to buy. I'm kind of weary on buying a used tektronix just based on a warranty stand point. On the other hand, I'd really like to get by for under $400. So my question is, do I go the "turned it on and everything seems to be working properly" tektronix eBay route, or buy a brand new digital scope with a warranty from a brand that I've never heard of. I figure either way I swing it, I'm in it for $400.

[selloutrr]

you only need a 20Mhz scope.
2 ch X and Y

You can buy a new one from fry's electronics for a $200

or a used one on ebay for $20 shipping will cost you more then the scope.

I've also had luck on craigslist.

[Cliff Schecht]

Ebay if you are feeling lucky and know what you want. Ebay is infested with people who buy used lab equipment, calibrate it and sell it for way too much money though so I usually avoid that route. Try to go local if you can, sometimes the local guitar tech will have a few and won't mind selling one.

[paulster]

Definitely 2 channel.

Make sure you get switchable 10x probes as well so you get the benefit of a really high impedance when diagnosing problems such as parasitic oscillation.

[selloutrr]

http://cnj.craigslist.org/search/sss?qu ... k=&maxAsk=

[Bruciep07]

And that's sort of the issue, I'm not really sure what my best option is, I've never personally owned a scope before, don't remember what brand we had in school, I really would just be perfectly happy with something that gave me decent enough resolution to compare outputs from different gain stages along the way, etc... If I could get something new with a warranty for $200, I'd be more than happy. If I could score a decent working scope on eBay for cheap, if also be happy. Problem with eBay/craigslist (as everyone knows) is you either take a chance on a questionable scope or pay out the ass for a "recently serviced/calibrated" scope. Any off-brands anyone can recommend that would be a good choice? I don't have a fry's near me(that I know of)...

[selloutrr]

I recommend if you purchase a new or used piece of test equipement you get it calibrated and continue to have it calibrated on a regular basis. After all you do count it being right.

Some units have the calibration specs in the owners or service manuals it is possible to calibrate some pieces of equipment yourself.

[Cliff Schecht]

Maybe look into a USB oscope. There are a lot of options from the $35 kit range to the $10,000 professional stuff and they are pretty neat little gadgets for light oscope work. You can buy some models with built in function generators and network analyzers that let you do very nice FFT plots, network analysis (i.e. loop gain, open/closed loop response, etc) and of course the basic oscope functions. About $200 gets you a decent two-probe setup with a built in function generator and software, probably usable probes as well.

Most can't take over 20-30V in the front end with a standard 1x probe though so make sure whatever you're buying can handle the voltage range you are working with. This is a HARD limit too, you will quickly ruin your device going over this limit. I blew up a nice Fluke meter recently measuring a big HV transformer on a variac and not being careful. I wasn't thinking about the fact that 850V RMS is over 1000V P-P until after the fact .

[sliberty]

you only need a 20Mhz scope.
2 ch X and Y

You can buy a new one from fry's electronics for a $200

Please provide a link. I just searched Fry's website and found nothing under $389

[Bruciep07]

The least expensive new scope I've found so far is this

www.saelig.com/PSBEB100/PSSA002.htm

Mf'd by owon, model #PDS5022S. It's got a 25MHz bandwidth, 100MS/s sample rate, 300V p-p max input voltage, etc... $287...

[sliberty]

Here is the cheapest new o-scope I could find on eBay:

http://cgi.ebay.com/NEW-20MHZ-ANALOG-OS ... 563aae1504

$235 including shipping.

Anybody know this brand / model?

[sliberty]

There are also some single channel 10mHz scopes on eBay for cheaper.

[jelle]

This one looks nice:
http://cnj.craigslist.org/ele/1972808427.html

My advice is to look on craigslist for a scope for under 100$ from a person who can show that the unit works and displays a sine wave.

Hope this helps,

Jelle

[Structo]

Of course the newer digital scopes are more money.
That is probably why the older CRT scopes are going for less money these days.

I'd like to get one as well but after getting two tube testers from Ebay that didn't work properly (yes they were supposed to) I am leery of ebay for that type of electronics.

So local pickup is best so you can try before you buy.

Or buy new. I've seen the Tenma brand go for under $300.

Here is one for $200 but I think it has been discontinued.

http://www.mcmconnect.com/tenma/product ... illoscopes

[paulster]

Don't get a single channel or a 10MHz bandwidth one.

Whilst you can argue that we don't need anything like 10MHz, when you're trying to track down oscillations you can find that they're quite a way into radio territory and unless your scope has a good bandwidth you'll struggle to see the trace on the graticule.

20MHz will do, but 40MHz or more is better to be able to get a nice, bright trace.

As soon as you get a single channel you can't compare phase relationships. One of the useful things I use mine for is to check each OT I get in to ensure I know the relative wind direction between primary and secondary. Use the 1kHz square wave test signal into the primary and channel 1, and connect the secondary to channel 2. If they are in phase then you can mark both ground connections as the start of the wind. If they're out of phase then swap the primary and you're there.

This means you can guarantee that when you install your OT you won't get any positive-feedback squeals and also means you can cut the wires to length and solder just once rather than having to leave slack 'just in case'.