Protek Oscilloscopes

You did not mention what your specs for the scope are (banwith, storage yes/no, portability, etc.) - so this is what is necessary to know to give a more precise proposal.

So I say what I would do: Before buying a Protek, I'd rather pay for a used good condition Tektronix 465 or 2235/2235A. But that's my personal view :)

come back to the group with more infos about what you are using the scope for, so the answer might get more preciese.

hth, Andreas

Mostly for digital timing of pulse and clock frequencies up to 20Mhz and viewing synchronous and asynchronous serial data, byte sized packets. Also use for viewing output waveforms of boost and buck converters and small transducer frequencies of just a few mV p-p both from the device and at the output stage of an amplifier. Storage not necessary and would prefer a benchtop model. Multiplication of waveforms would be nice for VI product to get an average value but I know this would mean a high dollar DSO.

I have been strongly considering a used Tek analog such as the ones I've used at the local University, they have some old Tek 2225's that I'm hoping they might auction off. I do see them from time to time used online.

Other than those specifics I would just use it to view various waveform from things like timers, charge and discharge cycles of capacitors and general purpose stuff like that.

they'd

Thanks.

Congratulations on taking the big step. I'd get a used Tektronix 465, but either one is far better than none.

Just get what you're comfortable with. If you're a newbie, eventually you'll have enough confidence in your skill to open up a scope and fix it if something goes wrong. The old Tek 465s were great scopes, and are eminently repairable. Until then, a new one might make you more comfortable, in which case the Protek is OK. I haven't heard anything about reliability issues on these, although I don't have one. You do get a warrantee if something goes wrong.

Good luck Chris

For 20MHz digital work you'll need at least a 100MHz scope to be able to view rise and fall times and detail etc

The Protek ones are OK as far as new scopes go, but new scopes are very poor value compared with a good second hand scope like a Tek. It might be worthwhile paying a bit extra to get a properly reconditioned unit that has been calibrated and checked etc. If you buy a second hand one on eBay then you take your chances.

For viewing your actual data packets you'll need a digital scope. Extremely handy when you can look at the individual bits to see whats happening. In fact it may be wise to consider two scope, despending on your budget of course. A nice 100MHz analog for your serious analog and real-time work, and an old clunker DSO (plenty of old HP ones around on eBay for a few hundred bucks) for checking data packets with. A DSO is also very useful for discharge curve checking.

Dave :)

okay, wit htthese infos I'd say stay with a Tek465 or 475. Or a Tek

Philips made few analog scopes with integrated anlogue multiplier (especially for VI work applications). But that's in the 1975 to 1980, so these units are really old now. I would not recommend to check the used market for this, it's not worth the money.

The 2225 from university are nice 50 MHz scopes. Not built to the durability a 465 or 2235 has been, but at least the work satisfactorily. Tektronix had to serve the low-price end market with these 2225, so that's the reason for the quality (or lack there of). As the other postes say: for a 20 MHz digital signal, there is considerabel aberration on the signal edges with a 50 MHz scope -- so be aware of this. If you can get these scopes cheap (80 to 120 $), in working condition, then go for 'em. But keep in mind that a good 465 is also in the same price region.

hth, Andreas