Tektronix 2205 vs 2235 vs 2440 for beginner

[Bhudie]

Hi Guys,

I'm looking for a little direction on which way to go. 

I'm about to dive in and buy my first scope.  I've put together a couple of 1176s and plan on doing at least 4 or 5 more projects including EQs and Mics, and I think it's time I invested in a scope.  I'm looking at 3 scopes right now on ebay.  I don't want to break the bank, but because I'm new to this, I'm willing to spend a small bit more for reliability. 

I was looking at these 3 scopes on ebay (tektronix 2205, 2235, 2440), and I was wanting to get an opinion on them.  Seems like I can get a 2205 with probes for about $185 after shipping. So my first questions are:

1. Will the 2205 meet my needs for audio?
2. What features is it lacking that I might find useful as I grow into it?

For a little over a hundred more I can get either a 2235 or a 2440.  So my next questios are:

1. Is one or the other of these better than the other for Audio DIY?
2. Are either/both better for Audio than the 2205?
3. Is it a problem to get a scope that's too fast?  i.e. does going for the fastest 2440 actually impact work with lower frequencies?


To give some perspective.  I understand that the 2440 is a 4 channel scope (to be honest, I don't yet have an idea how I would use the extra two channels...), and that it's faster at 300MHz(is this overkill??).  I have, however, spoken a bit with the seller of the 2440 and he appears to be a reputable seller (retired electrical engineer that refurbs and calibrates scopes).  If possible I'd like to get the cheapest one I can that won't leave me wanting to buy another, and I don't want to spend more than $300, and ideal world it would be $200...

Any help would be appreciated.  Again, I'm a total newb when it comes to scopes.  In fact, I'm fairly newbish full stop in electronics

Thanks,
Aaron

 

[PRR]

> Will the 2205 meet my needs for audio?

"Will a 2002 Honda Civic fit my needs for transportation?"

Depends. At the time, I had a b-i-g dog, so I opted for the larger 4-door Accord. He's gone, I have Corgis, now the Civic would be ample. OTOH, sometimes I covet full sheets of plywood, and want my old Willys Wagon back. And wonderful as the Honda is, sometimes I get a hankering for a car with style, such as my 1967 Cougar (but NOT the Cougar's cheapo chassis).

I don't know how big or stylish your dog is.

However I learned a LOT from a 1-ch "450KHz" 'scope which hardly did 100KHz.

And at present my fastest 'scope is, again, a 450KHz (though an honest 450KC).

I've owned 20MHz and 60MHz 'scopes. I've rarely seen anything in them that wasn't hinted by slower 'scopes. One time I did have a MHz parasitic, but it just would not sync, and I don't think that getting a good look at it would have changed my solution.

I don't currently own any 2-ch scope. That frill is useful, but not essential.

Forget speed.

Don't drown in channels.

As a beginner, you don't want a lot of knobs to set-wrong. 5 is better than 10, 10 is better than 20, half of which you may never understand.

I have the early Velleman hand-scope. It's quite useful, despite being "short on specs"; and VERY much better fit on the bench.

Today, for low-volt (<50V) work, for get-it-done, I'd seriously consider the new breed of hand-scope such as ARM Pocket Size Digital Oscilloscope
http://www.suntekstore.com/goods-14001530-v15_arm_pocket_size_digital_oscilloscope.html
Yes, it has "too many knobs". (The GameBoy interface conceals a LOT of choices; I'd rather have a few knobs.) But it does the job, doesn't break the bank, leaves you some money for a later day when you decide you must have something bigger/faster/knobbier.

 

[Bhudie]

Thanks PRR, this is exactly the kind of advice I was looking for.

As for your suggestion...  It sounds like a perfect solution for me, however, I read this in another thread:

...Be careful with some of the more affordable digital scopes, in that the screen refresh rate can be quite slow... This can make it difficult to get a clear picture of some waveforms. Entry-level digi scopes can also be noisier than a good analogue scope for similar money - so signals below 5mV can morph into fuzz. ...

Justin

Is your opinion that this is untrue of the scope you suggested? Or more that my inexperience and intended use of the scope means that the issues that I would run into with a more affordable digital scope are irrelevant? 

My immediate concern is not being able to see distortion when doing calibrations on the projects I build like the 1176.  This could totally be unfounded, as I have stated earlier that I am a newb... 

Thanks again for your help, it's much appreciated.

Aaron

 

[radardoug]

If you are doing tape recorders, 2 channels is good for doing azimuth. 2 channels definitely very usefull. Anything where you need to do comparative measurements.
I have two scopes, one analog, one digital. They both have pluses and minuses.
The digital is great for doing measurements such as clock frequencies, grab a screen and then measure in your own time. Or use the auto measurements. The analog is sometimes better for quick and dirty.
If you are working on digital logic, the faster the better. Audio not so much, although if you are servicing fet amps, a fast scope is usefull. Fets can do lots of stuff at high frequencies.

 

[My3gger]

I have nice 4ch 100MHz Tektronix 2247A. I find it nice that it has 2mV sensitivity which is good for audio work, i never used more than 2 channel, and i love cursors (at first i didn't care for them) because i can measure voltage and frequency. Nice thing is that you are in the US/Canada where good analog Tek or HP scopes are very cheap compared to Europe. Try to buy from someone who repairs scopes and have good reputability. When i was buying a friend helped me check all functions because i could return it if anything was wrong.
Tek 2225 used to be very cheap and has 500uV sensitivity which is nice for audio.