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Dagwood 24th August 2012 08:21 AM

hewlett packard 54601a
 
Hi

Just picked a hewlett packard 54601a on the NZ version of Ebay for $180 USD.

Just wondered what people who own one think of them?? there dont seem to be any reviews online (due to age I guess?).

Any trick or things to watch for?

Cheers
Dagwood

macboy 24th August 2012 03:08 PM

We used those when I was in university (aka college in USA). I recall that they were intuitive and easy to operate, but also rather basic, as far as digital scopes go. The "autoset" feature actually worked quite well as I recall, which can not be said of all digital scopes. It seems to have a rather low sample rate (20 MS/s?) but like all digital scopes it will repeatedly sample repetitive waveforms to gradually build up a representation of the waveform. It has only an 8-bit vertical resolution, which is only "OK". It has trigger holdoff, which I really wish my digital scope had.

I recall that there was a special key sequence that you could hit (on the 'soft keys' under the CRT) that would enable a Tetris game easter egg. I forget what it is.

Make sure to go to the Agilent website and download the user and service manuals and any other documents that you may need. The availability of these manuals is a tremendous bonus for anyone acquiring used HP/Agilent lab gear. I came to own an old HP power supply, built in the mid 60's (over 45 years ago!) and just went to the Agilent site and downloaded the manuals. Amazing. I spent many hours trying to find manuals for my various other non-HP/Agilent gear, and never did find many of them.

Here is a page for all 546xx series:
Discontinued 54600 Series Oscilloscopes | Agilent
Documents for 54600B (manual is common for 00/01/02)
54600B 2 Channel 100 MHz Oscilloscope [Obsolete] | Agilent
In addition to the user/service manual, there is a "component level information package" which is more information like schematics, parts lists, etc.

Dagwood 27th August 2012 07:22 AM

Hi Macboy

Thanks for the info, I have saved a copy of the user and service manuals and will digest them while I wait for the unit to arrive from Christchurch.

Quote:

easy to operate, but also rather basic
Will suit me at this stage :)

Cheers

VivaVee 29th August 2012 05:11 AM

They were a very early DSO and suffer from a low sampling rate. Any DSO that claims a 100MHz bandwidth these days would have a 1GS/s sampling rate. Regrettably your 'new' scope is equivalent to a 10MHz analog scope on anything except a steady sinewave. I recall my venerable 20MHz Hitachi analogue scope being significantly more useful. The digital Tek scopes from the same era were no better.

If this is your first and only scope then you would be advised to do a little reading so you understand its not inconsiderable limitations. On the other hand, this scope was quite useful at making a noisy switch mode power supply output look really nice because it ignored all the high frequency transient information!

macboy 29th August 2012 02:31 PM

Quote:

Originally Posted by VivaVee (Post 3143839)
They were a very early DSO and suffer from a low sampling rate. Any DSO that claims a 100MHz bandwidth these days would have a 1GS/s sampling rate. Regrettably your 'new' scope is equivalent to a 10MHz analog scope on anything except a steady sinewave. I recall my venerable 20MHz Hitachi analogue scope being significantly more useful. The digital Tek scopes from the same era were no better.

If this is your first and only scope then you would be advised to do a little reading so you understand its not inconsiderable limitations. On the other hand, this scope was quite useful at making a noisy switch mode power supply output look really nice because it ignored all the high frequency transient information!

That is not an early DSO. My Tek 468 is an early DSO! 25 MS/s with no super-sampling capability. Claimed to have 10 MHz usable bandwidth in digital mode, but that's only true if you are OK with 2.5 samples per period. 1 or 2 MHz usable bandwidth is more like it. Luckily, it is also a very good 100 MHz analog scope (identical to a venerable 465B).

The HP is not only useful for sinewaves. Any repetitive signal within the bandwidth of the scope is going to be able to be displayed. However, there are limitations. Any signal component present that is not correlated to the trigger source is likely to end up being at worst, completely averaged out, or at best, simply appear as some low-level noise on the waveform. All digital scopes, at their fastest horizontal rates, use super-sampling to build up the representation of the waveform over several (sometimes many) repetitions of the waveform since the real-time digital sampling rate can never be high enough. 1 GS/s would be considered quite fast for real-time, but such a scope would likely have a >1 GHz analog bandwidth and at least 10 GS/s (likely much higher) "equivalent time" sampling rate.

The advice to learn about the limitations of equivalent-time vs. real-time sampling is good advice for anyone with a DSO, even a shiny new modern one.

Terry Given 18th September 2012 01:08 PM

Years ago I tried to use one to do a "splat test" on an inductor (splat a charged cap across the inductor, measuring inductor voltage and current. if cap big, voltage ~ constant and current slope dI/dt = V_inductor/L so L can be calculated.

And I got precisely 3 dots in my measurement - whereupon I read the manual and found out just how low the single-shot sample rate was.

single-shot sample rate is perhaps a better term to use than real-time sampling rate - its self-explanatory.

the 546xx scopes also dont have much sample memory - so you need to be careful to avoid aliasing - if you cant trigger the scope but there's a nice looking waveform, its probably aliasing. I "discovered" this in my first real job, when my 12MHz 74HC14 xtal oscillator gave a ~20kHz output I couldnt trigger on - cue half an hour of frustration before a tech kindly turned the timebase knob for me.

Dagwood 9th November 2012 05:18 AM

1 Attachment(s)
Finally picked up the scope and when I got it home and fired it up this is what the screen looked like???

I have had a look through the manual but cannot find anything about screen settings

Any thoughts guru's??

Cheers

macboy 9th November 2012 01:17 PM

For one thing, it is inverted. And compressed vertically obviously.
This looks like an issue with the vertical part of the CRT driver circuits. The horizontal seems OK, it is full screen width and nice and linear. And the displayed waveform looks fine, so it looks functional. I am not a CRT guy so I can't really help.

Samuel Groner 9th November 2012 01:33 PM

Ouch... I can easily imagine how vertical compression could occur, but how do you get the image mirrored..? Perhaps someone tried to fix it and swapped a balanced line? As always, start by checking the supply voltages (with care, as dangerous voltages may be involved here).

Samuel

Dagwood 10th November 2012 01:34 AM

Hi Macboy and Samuel

Thanks for your thoughts

Damn...if it seems to good to be true it probably is!

I'm not keen on frying myself on this, may be better if I try to find a HP tech in New Zealand and get it looked at??


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