Looking at a HP54501A... - Page 1
Forum section: electronics / testgear

author: ruku
author_rank: Contributor
timestamp: July 07, 2011, 08:06:51 pm
content: Hey all, I'm looking at scopes again. Drooling, dreaming, and hoping.Right now I've found a decent deal on an in-shape HP54501A. I'm interested to see if anyone has any experience with these, and what they think about it. I know I found someone with an 02A, which is the 400 MHz model. I'm not entirely sure I want to buy just a 100 MHz scope, since I'd like to try doing some 2 meter amateur radio circuits.For $225 as a first scope, what do you all think? Would you be content with an 8-bit A/D or would you want something else? Anyone have nightmare stories about the scope falling to pieces?

author: Unknown
author_rank: Unknown
timestamp: July 08, 2011, 10:59:15 am
content: Quote from: ruku on July 07, 2011, 08:06:51 pmWhy would you want to use a scope to look at a modulated signal? This is usually fairly useless, other test equipment like spectrum analyzers and power meters are used for this.Quote from: ruku on July 07, 2011, 08:06:51 pmI'm not familiar with the scope and its vintage. How's the real time sampling rate? Memory depth? If it's an early DSO, the controls and responsiveness may not be great. 8-bit is standard, nothing wrong with that for a scope. Most don't get anywhere close to 8 effective bits anyway at higher frequencies. A scope is not a precision instrument with a large dynamic range.

author: vtl
author_rank: Regular Contributor
timestamp: July 08, 2011, 11:23:12 am
content: $225 is quite steep I think. This is an early digitizing scope with only 10M/S which is kind of limiting. You'd be probably limited to about 1MHz signals in single shot mode. Maybe you could consider the Rigol ds1052e which is quite popular here.

author: saturation
author_rank: Super Contributor
timestamp: July 08, 2011, 12:59:45 pm
content: For 2 meter band hams, I presume you need ~ 150 MHz accurately, alas that HP is outdated, as others have described, mostly particularly its low sampling rate.http://www.home.agilent.com/upload/cmc_upload/All/hp54501a.ih?&cc=US&lc=engIf you really need 150 MHz, you're only bet at that price range is a good used analog scope, or you'll have to move up to at minimum, at 3x your price range, a Rigol style DSO in the 100 MHz range, or in the $400 range, risk hacking a 1052e to 150 MHz.

author: EEVblog
author_rank: Unknown
timestamp: July 08, 2011, 01:07:25 pm
content: Quote from: vtl on July 08, 2011, 11:23:12 amI'd go one step further and say it's pretty much useless as a single shot scope. In which case an equivalent bandwidth analog would be a better option.But getting one for that price might be rather hard.Dave.

author: EEVblog
author_rank: Unknown
timestamp: July 08, 2011, 01:12:53 pm
content: Here is a nice Tek 2465A, a superb analog scope, $350MHz for $400eBay auction: #150626077856or a 250Mhz Tek 475A for $270:eBay auction: #260813412483A nice 200MHz Philips Combiscope for $400:eBay auction: #330581792710Dave.

author: ruku
author_rank: Contributor
timestamp: July 08, 2011, 05:04:14 pm
content: Quote from: EEVblog on July 08, 2011, 01:07:25 pmVtl and dave, That's exactly what I was worried about... 8 bit @ 10 Msps seemed a little limiting, I just had no idea what to expect.Vtl you were right about it being 1 MHz in single shot. What exactly does that mean?I've (ironically) seen a 2465B for a good price... I think I'm gonna track that guy down and see if its still for sale.

author: ruku
author_rank: Contributor
timestamp: July 08, 2011, 05:05:35 pm
content: Quote from: alm on July 08, 2011, 10:59:15 amThe memory depth has 501 samples. I'm guessing that's bad.And while spectrum analyzers and power meters would be nice... but I need a decent scope tooYou have a point.

author: gregariz
author_rank: Frequent Contributor
timestamp: July 08, 2011, 08:56:28 pm
content: Quote from: ruku on July 08, 2011, 05:05:35 pmA scope will be just fine to adjust AM/SSB modulation. A deviation meter for FM. Other digital/analog modes will generally need a purpose built test set.

author: vtl
author_rank: Regular Contributor
timestamp: July 09, 2011, 02:55:23 am
content: Quote from: ruku on July 08, 2011, 05:04:14 pmDave's gone over it in the beginner's oscilloscope video, highly recommened. When you use an oscilloscope you often want to look at signals that are not periodic, I mean, if all your signals are perfect and periodic you probably didn't need to look at it with an oscilloscope.So you want to capture a single burst and look at the data and in this mode the scope will take a number of samples which for this scope is 10M/S. Now to look at the signal properly you'll ideally want minimum of 10 or more samples per period of the signal youre trying to capture. So for this scope 10M/10 = 1MHz. Lets not forget the sample memory because these samples are stored. This scope was manufactured in an era where memory was expensive so your capture won't cover much either.

author: Frangible
author_rank: Regular Contributor
timestamp: July 11, 2011, 09:59:50 pm
content: That's not a bad scope for digital debugging work. I used one for a while in the early 90s - long before today's crop of wonder-scopes were available. One thing about these scopes is that they do not have a high sample rate, so they will very often display a bogus signal if what they are measuring is above Nyquist. For $225 I would expect to also receive a student-grade analog scope of the same vintage in the package, as you will certainly need it to back up that one.