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Jon Kåre Hellan

Oscilloscopes

Hi

I'm thinking about buying a scope. I've seen many people recommend
getting an old analog scope, but they're big! I borrowed a compact 100
MHz digital scope from work, and it was nice. 50 MHz scopes are a lot
cheaper, though.

Will I regret getting a 50 MHz scope instead of a 100 MHz one?

73
Jon LA4RT
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Don Wilhelm-4

Re: Oscilloscopes

Jon,

For use on the HF bands, go for a 'scope rated at 100 MHz or higher, and
be certain to use probes that are also rated for 100 MHz or more.
The frequency rating of a 'scope is the point where the vertical
response is down 3 dB, so you will not be able to do valid voltage
measurements at frequencies beyond about 1/3 of the frequency rating of
the 'scope. The 50 mHz 'scope will give valid voltage measurements up
to about 16 MHz while the 100 MHz 'scope will be good up through 30 MHz.

If good measurement of voltages is not important to you, then the 50 MHz
'scope may be OK, even though the voltage (signal amplitude) may be
attenuated, it will still show a proper waveform up to its rated
frequency and often beyond - unless the input waveform is a pulse or a
square wave where the rise time is one of the important parameters - for
most amateur radio purposes, that is not important.

Analog vs. Digital - no comment, but I prefer the real time analog
'scope, no potential digital artifacts to deal with.

73,
Don W3FPR

Jon Kåre Hellan wrote:

> Hi
>
> I'm thinking about buying a scope. I've seen many people recommend
> getting an old analog scope, but they're big! I borrowed a compact 100
> MHz digital scope from work, and it was nice. 50 MHz scopes are a lot
> cheaper, though.
>
> Will I regret getting a 50 MHz scope instead of a 100 MHz one?
>
> 73
> Jon LA4RT
>
>

hf4me

Re: Oscilloscopes

How do you know what the frequency rating of a scope is?
What is the rating of my Techtronics 475?
We used them at work for required adjustments to tolerances of 2/10
nanoseconds.

Thanks es 73, de Jim KG0KP

----- Original Message -----
From: "Don Wilhelm" <[hidden email]>
To: "Jon Kåre Hellan" <[hidden email]>
Cc: "'Elecraft List'" <[hidden email]>
Sent: Thursday, May 21, 2009 8:02 AM
Subject: Re: [Elecraft] Oscilloscopes

Jon,

For use on the HF bands, go for a 'scope rated at 100 MHz or higher, and
be certain to use probes that are also rated for 100 MHz or more.
The frequency rating of a 'scope is the point where the vertical
response is down 3 dB, so you will not be able to do valid voltage
measurements at frequencies beyond about 1/3 of the frequency rating of
the 'scope. The 50 mHz 'scope will give valid voltage measurements up
to about 16 MHz while the 100 MHz 'scope will be good up through 30 MHz.

If good measurement of voltages is not important to you, then the 50 MHz
'scope may be OK, even though the voltage (signal amplitude) may be
attenuated, it will still show a proper waveform up to its rated
frequency and often beyond - unless the input waveform is a pulse or a
square wave where the rise time is one of the important parameters - for
most amateur radio purposes, that is not important.

Analog vs. Digital - no comment, but I prefer the real time analog
'scope, no potential digital artifacts to deal with.

73,
Don W3FPR

Jon Kåre Hellan wrote:

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AC7AC

Re: Oscilloscopes

In reply to this post by Jon Kåre Hellan

CONTENTS DELETED

The author has deleted this message.

Don Wilhelm-4

Re: Oscilloscopes

In reply to this post by hf4me

Jim,

You have to know the 'scope specs. The Tek 475 scope is a 200 MHz
'scope, the 465 is 150 MHz.
The frequency rating of the probes will also provide an upper limit.

The resolution on the time axis is quite a different consideration than
the frequency rating for the amplitude (and rise time) response of the
vertical amplifier. Normally, the 'scope's frequency is stated as the
response for the vertical amplifier.

73,
Don W3FPR

Jim Miller KG0KP wrote:
> How do you know what the frequency rating of a scope is?
> What is the rating of my Techtronics 475?
> We used them at work for required adjustments to tolerances of 2/10
> nanoseconds.
>
> Thanks es 73, de Jim KG0KP
>
>
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Alan Bloom

Re: Oscilloscopes

In reply to this post by Jon Kåre Hellan

On Thu, 2009-05-21 at 10:20 +0200, Jon Kåre Hellan wrote:

Of course, it depends on what you plan to use the scope for. For
troubleshooting high-speed digital circuits you want the widest
bandwidth possible. Overshoot and ringing on a bus line might be hard
to see with a 100 MHz scope and impossible with a 50 MHz scope.

On the other hand, the frequency response doesn't drop off a cliff right
at the specified bandwidth. For example, my 100 MHz scope works just
fine for looking at narrow-band signals in the two meter band. The
response is down a couple dB but for narrow-band signals that's not a
problem.

It's an HP54600A digital scope, but I doubt an analog scope would be
much different in this respect. A graph of the frequency response
(measured with an HP8656B signal generator) is posted here:
http://www.cds1.net/~n1al/ham/54600.GIF

As you can see, this "100 MHz" scope is usable up through at least the
220 MHz band (at -7 dB).

Al N1AL

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Alan Bloom

Re: Oscilloscopes

In reply to this post by AC7AC

On Thu, 2009-05-21 at 08:13 -0700, Ron D'Eau Claire wrote:

> I agree with Don, I like analog scopes. Any time a signal is taken to bits
> (literally!) and then reassembled there are display artifacts and some
> accuracy of the waveform is lost but, you're quite right, analog scopes are
> *big* and heavy.

I also dislike most digital oscilloscopes. On most of them, it is
obvious that the user interface was designed by a software person, hot a
hardware engineer. I hate having to search through multiple layers of
menus to access some simple function.

However, the HP54600-series oscilloscopes are different. They combine
the advantages of digital with the look and feel of an analog scope.
There are separate knobs for all the most-used functions. The design
team was lead by Bob Witte K0NR who knows a thing or two about what a
hardware engineer wants in an oscilloscope.

HP/Agilent no longer sells the 546XX, but you can occasionally find one
on the used market. Scanning down the list on Ebay I see an HP54620A
(version with built-in logic analyzer) with a starting bid of $200, two
54610B's (500 MHz, dual channel) starting at $700 and $725, HP54600A
with optional GPIB module $500, etc.

> Again, good digital scopes are the more expensive scopes.

Generally true. I bought mine brand new (with employee discount) some
years ago and have never regretted it. For once in my life, it's nice
to have a no-compromise, reliable piece of test equipment.

By the way, if you do decide on analog, the HP1740 100 MHz scope is a
very good choice. (Much better than most of the analog scopes HP came
out with over the years.) They often show up on Ebay.

Al N1AL

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Matt Palmer-4

Re: Oscilloscopes

I would stay away from early hp digitals, they are nothing but
trouble, just take my word on this one, you are better off with a 2430
(might have dyslexic on the number)

The new digital lunchboxes are nice too, and if you know what you are
doing you have no problems, I attribute the 'old timers' being wary of
them to not knowing how to properly use them. Since I grew up with a
infiinium, i've never had a problem seeing and removing aliasing
errors and others, but you have to have a decent sense for what to
expect to see, and know which way to turn what knobs to make it look
right. (like adjusting sample rate etc.)

Matt
W8ESE
Former KD8DAO
http://blog.MattIsKichigai.com

On Thu, May 21, 2009 at 11:23 AM, Alan Bloom<[hidden email]> wrote:

> On Thu, 2009-05-21 at 08:13 -0700, Ron D'Eau Claire wrote:
>
>> I agree with Don, I like analog scopes. Any time a signal is taken to bits
>> (literally!) and then reassembled there are display artifacts and some
>> accuracy of the waveform is lost but, you're quite right, analog scopes are
>> *big* and heavy.
>
> I also dislike most digital oscilloscopes. On most of them, it is
> obvious that the user interface was designed by a software person, hot a
> hardware engineer. I hate having to search through multiple layers of
> menus to access some simple function.
>
> However, the HP54600-series oscilloscopes are different. They combine
> the advantages of digital with the look and feel of an analog scope.
> There are separate knobs for all the most-used functions. The design
> team was lead by Bob Witte K0NR who knows a thing or two about what a
> hardware engineer wants in an oscilloscope.
>
> HP/Agilent no longer sells the 546XX, but you can occasionally find one
> on the used market. Scanning down the list on Ebay I see an HP54620A
> (version with built-in logic analyzer) with a starting bid of $200, two
> 54610B's (500 MHz, dual channel) starting at $700 and $725, HP54600A
> with optional GPIB module $500, etc.
>
>> Again, good digital scopes are the more expensive scopes.
>
> Generally true. I bought mine brand new (with employee discount) some
> years ago and have never regretted it. For once in my life, it's nice
> to have a no-compromise, reliable piece of test equipment.
>
> By the way, if you do decide on analog, the HP1740 100 MHz scope is a
> very good choice. (Much better than most of the analog scopes HP came
> out with over the years.) They often show up on Ebay.
>
> Al N1AL
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

Alan Bloom

Re: Oscilloscopes

On Thu, 2009-05-21 at 11:31 -0500, Matt Palmer wrote:
> ... Since I grew up with a
> infiinium, i've never had a problem seeing and removing aliasing
> errors and others, but you have to have a decent sense for what to
> expect to see, and know which way to turn what knobs to make it look
> right. (like adjusting sample rate etc.)

One nice thing about the HP54600A is that, although the sample rate is
only 20 MHz, they dither the sample phase on successive sweeps, which
achieves a much higher effective sample rate. You can view signals well
over 100 MHz without distortion.

That only works on repetitive signals. For single-shot events you are
limited to the 20 MHz sample rate, which means signals over the 10 MHz
Nyquist frequency are aliased.

Al N1AL

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Carl Clawson

Re: Oscilloscopes

In reply to this post by hf4me

>
> What is the rating of my Techtronics 475?
> We used them at work for required adjustments to tolerances
> of 2/10 nanoseconds.
>
> Thanks es 73, de Jim KG0KP

For any common model you can easily find info on the web if you aren't sure.
Bandwidth for scopes is like horsepower for a performance car. It'll be the
first spec that's mentioned.

A handy rule of thumb for the 10% to 90% rise time is ln(9)/(2*pi*bandwidth)
= 0.35/bandwidth. So a 200 MHz scope has an inherent rise time of a bit less
than 2 ns. The 485 comes in at an even 1.0 ns and I always suspected that's
why they targeted 350 MHz for its bandwidth spec.

Exercise for the reader: derive this formula assuming a single pole filter
response.

73 and thanks for listening
Carl WS7L
K3 #486

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Tom Hammond-2

Re: Oscilloscopes

In reply to this post by hf4me

Jim:

Just GOOGLE for 'tektronix 475' and then select one or more of the
links.

I quick search shows that the Tek 475 is a 200 MHz o'scope.

73,

Tom N0SS

At 10:06 05/21/2009, you wrote:

>How do you know what the frequency rating of a scope is?
>What is the rating of my Techtronics 475?
>We used them at work for required adjustments to tolerances of 2/10
>nanoseconds.
>
>Thanks es 73, de Jim KG0KP
>
>----- Original Message -----
>From: "Don Wilhelm" <[hidden email]>
>To: "Jon Kåre Hellan" <[hidden email]>
>Cc: "'Elecraft List'" <[hidden email]>
>Sent: Thursday, May 21, 2009 8:02 AM
>Subject: Re: [Elecraft] Oscilloscopes
>
>
>Jon,
>
>For use on the HF bands, go for a 'scope rated at 100 MHz or higher, and
>be certain to use probes that are also rated for 100 MHz or more.
>The frequency rating of a 'scope is the point where the vertical
>response is down 3 dB, so you will not be able to do valid voltage
>measurements at frequencies beyond about 1/3 of the frequency rating of
>the 'scope. The 50 mHz 'scope will give valid voltage measurements up
>to about 16 MHz while the 100 MHz 'scope will be good up through 30 MHz.
>
>If good measurement of voltages is not important to you, then the 50 MHz
>'scope may be OK, even though the voltage (signal amplitude) may be
>attenuated, it will still show a proper waveform up to its rated
>frequency and often beyond - unless the input waveform is a pulse or a
>square wave where the rise time is one of the important parameters - for
>most amateur radio purposes, that is not important.
>
>Analog vs. Digital - no comment, but I prefer the real time analog
>'scope, no potential digital artifacts to deal with.
>
>73,
>Don W3FPR
>
>Jon Kåre Hellan wrote:
> > Hi
> >
> > I'm thinking about buying a scope. I've seen many people recommend
> > getting an old analog scope, but they're big! I borrowed a compact 100
> > MHz digital scope from work, and it was nice. 50 MHz scopes are a lot
> > cheaper, though.
> >
> > Will I regret getting a 50 MHz scope instead of a 100 MHz one?
> >
> > 73
> > Jon LA4RT
> >
> >
>______________________________________________________________
>Elecraft mailing list
>Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>Post: mailto:[hidden email]
>
>This list hosted by: http://www.qsl.net
>Please help support this email list: http://www.qsl.net/donate.html
>
>
>______________________________________________________________
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>
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hf4me

Re: Oscilloscopes

Thanks everybody on the Tek 475 info. I use Google for a lot of things -
why don't I think of it in a case such as this ??? Old age gets the blame
again.

Thanks es 73, de Jim KG0KP

----- Original Message -----
From: "Tom Hammond" <[hidden email]>
To: "Jim Miller KG0KP" <[hidden email]>;
<[hidden email]>
Sent: Thursday, May 21, 2009 1:21 PM
Subject: Re: [Elecraft] Oscilloscopes

Jim:

Just GOOGLE for 'tektronix 475' and then select one or more of the
links.

I quick search shows that the Tek 475 is a 200 MHz o'scope.

73,

Tom N0SS

At 10:06 05/21/2009, you wrote:

Eric Swartz - WA6HHQ

Re: Oscilloscopes [END of Thread]

Administrator

Looks like Jim got the info he needed. Lets end this thread for now.

73, Eric WA6HHQ
Elecraft Moderator, and Dayton surviver.

Jim Miller KG0KP wrote:
> Thanks everybody on the Tek 475 info. I use Google for a lot of things -
> why don't I think of it in a case such as this ??? Old age gets the blame
> again.
>
> Thanks es 73, de Jim KG0KP
>
>
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