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General opinion on 180 series scopes?

 

I have had two 180A scopes in regular use for many years including a
range of plug ins
and have not had a single breakdown in all that time.
One is populated with an 1803A (bought new in the 70's for BIG bucks) and
the other scope with the
GP vert amp 1801A
I also have the service extenders which Ive never used yet, but now that
Ive posted
this I will probably have to use them soon!
The only hassle Ive had is with the 4 channel plug in I used to use on a 184
The sync take off is after the vertical

Very reliable scopes
 

Mike was correct of being on guard with the
capacitors. Heat is the biggest killer of electronic
components.
While it's true that electrolytics and heat don't mix all too well, I'd stay
away from such broad "heat is the killer" statements. Reading some Bob Pease
and trying things out convinced me that in most cases making things run cool
often does zilch for performance. In the end you have to measure worse
performance to claim that heat is the enemy. There are some well known things
such as leakage currents that scale bad with temperature, but those are
either designed-in or other precautions are taken. While I admit that
excessive operating temperature in power supplies is typically a sign of a
novice or misunderstanding designer, this doesn't equally carry on to other
parts of the circuitry. Disclaimer: Modern high integration CPUs are a
different story and I won't go into that.

Cheers, Kuba
John Day
 

At 09:22 AM 1/22/2007, Kuba Ober wrote:

Mike was correct of being on guard with the
capacitors. Heat is the biggest killer of electronic
components.
While it's true that electrolytics and heat don't mix all too well,
It is even more fair to say that internally generated heat and electrolytics don't mix well. It has been my experience over 35 years designing equipment that temperature rise due to losses in electrolytics does far more damage than external heat. Although modern, high performance electrolytics are much better (low cost 85C "jelly bean" electro's seem to be no better!) the losses will increase with age, thus so will dissipation and the entire process accelerates.

However, the assertion that capacitors are likely to be your biggest problem is pretty valid in most cases.

As for 180 series CRO's in general. They were, and remain, good performers. Easy to maintain, easy to find 'donor' instruments for them and with manuals very readily available. I used them very happily until about 1998. The only Tek CRO's I ever liked enough to own were a 475 portable and a 7904 high speed mainframe. But somehow the CRO closest to me for 20 years was a 180 series. I now happily use HP 546xx series DSO's.

I never succumbed to the cult of Tek!

John
[email protected]
 

Besides using caps from a 1st or 2nd tier manufacturers, remember when replacing Ta caps to provide enough voltage "headroom". One of the reasons the Ta caps fail is that the the rated voltage was too close to the in-circuit voltage. That works for Al caps, but not Tas.

-------------- Original message --------------
From: Thomas Hejl <tmhejl@...>
Paul,

According to list and description of the 180 series
scope that you gave, the 180C would appear to be the
best buy. Most probes are of the passive type (they do
not need an external additional power source to
operate). The X10 or 10X probes that I mentioned
should be passive as well. Check with the seller on
the specifications of them (I could not find specs.
right away on the HP10008A).
If you are on a budget (as most of us are), then there
are still other scopes that may perform as well and
are less expensive. A few in mind are the Tektronix
2213 and the 2215 at 60MHz and the 465 at 50MHz. These
are rather inexpensive, non-modular and are newer
machines than the 180's (which were made around 1987).
If the only choices you have are the 180's then stay
with the 180C (The 184 might be overkill).
Mike was correct of being on guard with the
capacitors. Heat is the biggest killer of electronic
components. More heat is generated from the units
power supply then probably anywhere else. It is these
capacitors that need the most attention.
Tantalum caps are both inexpensive and stable. That is
why manufacturers use them so often. When a circuit
requires stabilization in performance, tants are caps
of choice. Their biggest draw back is when they fail.
(In particular the dipped ones.) There will be no
warning. Some will simply short out internally and
work one day but not the next. Others will go like a
fire cracker sending carbon smoke throughout the unit
with the sound of a pop.
Electrolytic caps will give some warning sometimes.
They may start to bulge out. Performance gets weaker
due to poor ESR. See samples here at:


(If you ever do decide to replace any cap., make sure
it is made from a reliable manufacturer. Dell Computer
had a problem with caps a few years back due to the
purchase of bad caps from a poor source.)
So changing capacitors (in the power supply at least)
is a wise thing to do. Whether they are tantalum's or
electrolytic's it might save aggravation in the
future. As for changing ALL the tants I counted about
20 per plug-in on the ones I have in my shop. It is
going to be a task, so weigh your time, effort and
cost vs. probability of their failure. As far as
plug-ins go, I have not had one fail yet. The power
supply I would not take any chances on, replace them
at least.

Keep in Touch,
Tom

--- Paul Jacobson <pj@...> wrote:

Tom,

thanks so much for such an informative response.
in regards to the digital what i *think* i need is
to be able to view
two clock pulses simultaneously to ensure their
timing alignment with
each other is correct. so if I understand right the
180's with 50mhz
vert/horizontal plugins would be sufficient.

what is available is:
180A with 1801A, 1821A (approx $280AU)
180C with 1801A, 1821A (approx $320AU)
184C with 1805A, 1825A (approx $480AU)
all of these units come with 10008A passive voltage
probes, so I
think i'd need to factor in buying x10 probes?

The 184C is pushing the boundaries $ wise. The 180C
looks be in the
better condition cosmetically of the 180's as the
plugins on the 180A
don't appear to align quite right in the mainframe.

Checking the 180C service manual d/l'd from BAMA, it
appears to be
all discrete componentry, which is a bit reassuring
if something does
break.

I've been advised to replace all the tantalum caps
on units of this
age. Is that reasonable advice?


cheers
Paul
__________________________________________________________
8:00? 8:25? 8:40? Find a flick in no time
with the Yahoo! Search movie showtime shortcut.
John Day
 

At 02:51 PM 1/22/2007, you wrote:
Tantalum caps are both inexpensive and stable. That is
why manufacturers use them so often. When a circuit
requires stabilization in performance, tants are caps
of choice.
Not sure I would agree with that. In the era of equipment we are talking about tantalum caps were VERY expensive. They were used principally for their small size, better losses and lower ESR at higher frequencies. In terms of temperature co-efficient, many tantalums were better than aluminium caps, but this was generally not the reason they were chosen.

For the same reason, nowadays we often use special high value ceramic capacitors (2.2uf, 3.3uf, 4.7uf) not because of stability, but because they offer better ESR figures than even the best tantalums and thus offer better regulator stability in many power supplies. But you have to choose the right parts, otherwise a single top quality ceramic needs to be replaced with a tantalum and two ceramics in some cases.

In older equipment using tantalums (usually the early teardrop ones) you should make sure you have a good ceramic bypass across the tantalum. Back in the mid-80's we tested that tantalums for breakdown at high voltage and reverse voltage - very difficult to get them to fail. But let too much RF appear across the tantalum and you could almost always guarantee holes in the ceiling! But you need to be careful even today. I have seen modern surface mount tantalums for Kemet explode with RF. However, I have never lost one that I could attribute to overvoltage or reverse voltage.

John
 

Currently eBay is showing 1804a 4 channel plugins for around $20-50. The 1804 does 4 channels but no math. The 2 channel units have addition and the specs say when one Chanel is inverted it acts like a differential input instrument! The 1821 dual time base is spectacular. It can be set up to have a variable width time delayed window within the display which is higher intensity on the screen and thus can magnify a signal within the signal. Also, a trigger can be set within that segment and a separate external trigger can be use for the main and the delayed segment. This gets you behavior like on a digital storage scope. Imaging the ability to trigger on certain glitches during the delay time. I used to use it to pluck out separate scan lines in an NTSC composite signal. Set up a separate circuit to count pulses in the signal and feed the counter output into the secondary trigger and you could pick the scan line. This is very flexible triggering. ?Fun to use scope. I just picked up a 4 channel plug in and now have a 4 channel analog scope. ?Screen display is rock solid when you get the trigger set up. The scope is intuitive to use. Schematics available. I think it is a great beginner scope if working. It is easy to repair with all discreet components. It has a cool feature of a signal delay line so you can see a bit of the signal before the trigger fires.
 

HP-180-series ¡®scopes have passed through my hands but I¡¯ve never collected one. They were HP¡¯s first all-solid-state high-end oscilloscope. Components are densely packed into the chassis and tend to run warm; cooling is important for lifetime. Make sure the fan is running well, filter is clean, all dust blown out.?

Jeremy?

On Mon, May 31, 2021 at 7:53 AM sholland via <sholland=[email protected]> wrote:
Currently eBay is showing 1804a 4 channel plugins for around $20-50. The 1804 does 4 channels but no math. The 2 channel units have addition and the specs say when one Chanel is inverted it acts like a differential input instrument! The 1821 dual time base is spectacular. It can be set up to have a variable width time delayed window within the display which is higher intensity on the screen and thus can magnify a signal within the signal. Also, a trigger can be set within that segment and a separate external trigger can be use for the main and the delayed segment. This gets you behavior like on a digital storage scope. Imaging the ability to trigger on certain glitches during the delay time. I used to use it to pluck out separate scan lines in an NTSC composite signal. Set up a separate circuit to count pulses in the signal and feed the counter output into the secondary trigger and you could pick the scan line. This is very flexible triggering.? Fun to use scope. I just picked up a 4 channel plug in and now have a 4 channel analog scope.? Screen display is rock solid when you get the trigger set up. The scope is intuitive to use. Schematics available. I think it is a great beginner scope if working. It is easy to repair with all discreet components. It has a cool feature of a signal delay line so you can see a bit of the signal before the trigger fires.

--
Jeremy Nichols
6.
 

As far as I remember ... there were no fans in the 180 series 'scopes or their plug-ins. Could anyone confirm this ?

Joel Setton
 

¿ªÔÆÌåÓý

Greetings,

I owned a 180A with 1801A and 1821A plug-ins and I do not recall any fan.

Additionally, there is a photo showing the 180A without covers or plug-ins in the 1967 HP catalog and no fans are visible.

Hope this helps.

Regards,

Ken


On 31May, 2021, at 12:59 PM, Joel Setton <setton@...> wrote:

As far as I remember ... there were no fans in the 180 series 'scopes or their plug-ins. Could anyone confirm this ?

Joel Setton

 

Hi,
my 180AR doesn't have any fan for sure.
Also no fan in any of the 182B/C/T displays that I happened to have
seen in the past.
HTH
Frank IZ8DWF

On Mon, May 31, 2021 at 9:23 PM ken chalfant <kpchalfant@...> wrote:

Greetings,

I owned a 180A with 1801A and 1821A plug-ins and I do not recall any fan.

Additionally, there is a photo showing the 180A without covers or plug-ins in the 1967 HP catalog and no fans are visible.

Hope this helps.

Regards,

Ken


On 31May, 2021, at 12:59 PM, Joel Setton <setton@...> wrote:

As far as I remember ... there were no fans in the 180 series 'scopes or their plug-ins. Could anyone confirm this ?

Joel Setton
 

¿ªÔÆÌåÓý

No fans in mine, and I have several in both scope & spectrum analyzer configurations. Common failures are the HV resistors around the CRT, and the output stage resistors in the deflection amplifiers. All easy to fix. Oddly I have never had a semiconductor failure in any of mine ¨C it¡¯s always the passives that die.

?

Ancient, but nice, gear. Relatively easy to work on and full service docs readily available.

?

Ken

?

?

?

From: [email protected] <[email protected]> On Behalf Of ken chalfant
Sent: May 31, 2021 3:23 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] General opinion on 180 series scopes?

?

Greetings,

?

I owned a 180A with 1801A and 1821A plug-ins and I do not recall any fan.

?

Additionally, there is a photo showing the 180A without covers or plug-ins in the 1967 HP catalog and no fans are visible.

?

Hope this helps.

?

Regards,

?

Ken

?

?

On 31May, 2021, at 12:59 PM, Joel Setton <setton@...> wrote:

?

As far as I remember ... there were no fans in the 180 series 'scopes or their plug-ins. Could anyone confirm this ?

Joel Setton

?
 

I had a 180 when I worked for -hp-, I don't remember it having a fan. I thought it was a pretty good scope.

On 5/31/2021 11:59 AM, Joel Setton wrote:
As far as I remember ... there were no fans in the 180 series 'scopes or their plug-ins. Could anyone confirm this ?

Joel Setton
--
Richard Knoppow
dickburk@...
WB6KBL
 

OK, good?to know, so I was wrong, no fan.?


On Mon, May 31, 2021 at 1:15 PM Richard Knoppow <dickburk@...> wrote:
??? I had a 180 when I worked for -hp-, I don't remember it
having a fan. I thought it was a pretty good scope.

On 5/31/2021 11:59 AM, Joel Setton wrote:
> As far as I remember ... there were no fans in the 180 series
> 'scopes or their plug-ins. Could anyone confirm this ?
>
> Joel Setton
>

--
Richard Knoppow
dickburk@...
WB6KBL






--
Jeremy Nichols
6.
 

¿ªÔÆÌåÓý

Hi all

Regarding HP 180 scopes ?if you ever get mains ripple on the display most probably it is a 10 uf at 100 v axial that requires changing? suggest you go for 150 volt at 15? uf

Regards Paul

?

From: [email protected] [mailto:[email protected]] On Behalf Of Jeremy Nichols
Sent: 31 May 2021 21:37
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] General opinion on 180 series scopes?

?

OK, good?to know, so I was wrong, no fan.?

?

?

On Mon, May 31, 2021 at 1:15 PM Richard Knoppow <dickburk@...> wrote:

??? I had a 180 when I worked for -hp-, I don't remember it
having a fan. I thought it was a pretty good scope.

On 5/31/2021 11:59 AM, Joel Setton wrote:
> As far as I remember ... there were no fans in the 180 series
> 'scopes or their plug-ins. Could anyone confirm this ?
>
> Joel Setton
>

--
Richard Knoppow
dickburk@...
WB6KBL





--

Jeremy Nichols
6.
 

I picked up one of the 180 series and a small pile of plugins many years ago, and while I was very excited at the time, I soon lost interest because everything was flaky, and was poorly engineered (in my opinion). I guess I was expecting 7603 quality, but I've never seen a working Tek scope with that many issues.? The only other HP scope I have is a 175A, which needs power supply work, I've kept it because it's anchoring (literally) the bottom of a relay rack stacked with much lighter gear.? Maybe someday....

-Dave

On Monday, May 31, 2021, 08:04:26 AM PDT, Jeremy Nichols <jn6wfo@...> wrote:


HP-180-series ¡®scopes have passed through my hands but I¡¯ve never collected one. They were HP¡¯s first all-solid-state high-end oscilloscope. Components are densely packed into the chassis and tend to run warm; cooling is important for lifetime. Make sure the fan is running well, filter is clean, all dust blown out.?

Jeremy?

On Mon, May 31, 2021 at 7:53 AM sholland via <sholland=[email protected]> wrote:
Currently eBay is showing 1804a 4 channel plugins for around $20-50. The 1804 does 4 channels but no math. The 2 channel units have addition and the specs say when one Chanel is inverted it acts like a differential input instrument! The 1821 dual time base is spectacular. It can be set up to have a variable width time delayed window within the display which is higher intensity on the screen and thus can magnify a signal within the signal. Also, a trigger can be set within that segment and a separate external trigger can be use for the main and the delayed segment. This gets you behavior like on a digital storage scope. Imaging the ability to trigger on certain glitches during the delay time. I used to use it to pluck out separate scan lines in an NTSC composite signal. Set up a separate circuit to count pulses in the signal and feed the counter output into the secondary trigger and you could pick the scan line. This is very flexible triggering.? Fun to use scope. I just picked up a 4 channel plug in and now have a 4 channel analog scope.? Screen display is rock solid when you get the trigger set up. The scope is intuitive to use. Schematics available. I think it is a great beginner scope if working. It is easy to repair with all discreet components. It has a cool feature of a signal delay line so you can see a bit of the signal before the trigger fires.

--
Jeremy Nichols
6.
 

Dave, let me know if I can help with the 175A power supply; the low-voltage supplies are all solid state (except for one VR tube) and fairly simple. I have a working 175A and a parts unit. I¡¯m looking for a 1754A 4-channel vertical plugin for this ¡®scope.?

Jeremy?



On Mon, May 31, 2021 at 7:05 PM Dave Seiter <d.seiter@...> wrote:
I picked up one of the 180 series and a small pile of plugins many years ago, and while I was very excited at the time, I soon lost interest because everything was flaky, and was poorly engineered (in my opinion). I guess I was expecting 7603 quality, but I've never seen a working Tek scope with that many issues.? The only other HP scope I have is a 175A, which needs power supply work, I've kept it because it's anchoring (literally) the bottom of a relay rack stacked with much lighter gear.? Maybe someday....

-Dave

On Monday, May 31, 2021, 08:04:26 AM PDT, Jeremy Nichols <jn6wfo@...> wrote:


HP-180-series ¡®scopes have passed through my hands but I¡¯ve never collected one. They were HP¡¯s first all-solid-state high-end oscilloscope. Components are densely packed into the chassis and tend to run warm; cooling is important for lifetime. Make sure the fan is running well, filter is clean, all dust blown out.?

Jeremy?

On Mon, May 31, 2021 at 7:53 AM sholland via <sholland=[email protected]> wrote:
Currently eBay is showing 1804a 4 channel plugins for around $20-50. The 1804 does 4 channels but no math. The 2 channel units have addition and the specs say when one Chanel is inverted it acts like a differential input instrument! The 1821 dual time base is spectacular. It can be set up to have a variable width time delayed window within the display which is higher intensity on the screen and thus can magnify a signal within the signal. Also, a trigger can be set within that segment and a separate external trigger can be use for the main and the delayed segment. This gets you behavior like on a digital storage scope. Imaging the ability to trigger on certain glitches during the delay time. I used to use it to pluck out separate scan lines in an NTSC composite signal. Set up a separate circuit to count pulses in the signal and feed the counter output into the secondary trigger and you could pick the scan line. This is very flexible triggering.? Fun to use scope. I just picked up a 4 channel plug in and now have a 4 channel analog scope.? Screen display is rock solid when you get the trigger set up. The scope is intuitive to use. Schematics available. I think it is a great beginner scope if working. It is easy to repair with all discreet components. It has a cool feature of a signal delay line so you can see a bit of the signal before the trigger fires.

--
Jeremy Nichols
6.

--
Jeremy Nichols
6.
 

I haven't looked at the 175A in about 15 years (besides as its' function as large paper weight).? Is there a better scan of the manual then the one on BAMA?? As I recall, it was very hard to read at the time.? The main reason I shelved both it and the 18x was the two pallets of mostly Tek gear I got shortly thereafter.? ?The 7104s and 7844s in particular where much more fun to deal with, especially since they are considerably lighter!? I only got two plugins with the 175A, and I'd remember if it had four channels.? I'll eventually get back to them, but I need to make room first and dispose of many other things.

-Dave

On Monday, May 31, 2021, 08:58:30 PM PDT, Jeremy Nichols <jn6wfo@...> wrote:


Dave, let me know if I can help with the 175A power supply; the low-voltage supplies are all solid state (except for one VR tube) and fairly simple. I have a working 175A and a parts unit. I¡¯m looking for a 1754A 4-channel vertical plugin for this ¡®scope.?

Jeremy?



On Mon, May 31, 2021 at 7:05 PM Dave Seiter <d.seiter@...> wrote:
I picked up one of the 180 series and a small pile of plugins many years ago, and while I was very excited at the time, I soon lost interest because everything was flaky, and was poorly engineered (in my opinion). I guess I was expecting 7603 quality, but I've never seen a working Tek scope with that many issues.? The only other HP scope I have is a 175A, which needs power supply work, I've kept it because it's anchoring (literally) the bottom of a relay rack stacked with much lighter gear.? Maybe someday....

-Dave

On Monday, May 31, 2021, 08:04:26 AM PDT, Jeremy Nichols <jn6wfo@...> wrote:


HP-180-series ¡®scopes have passed through my hands but I¡¯ve never collected one. They were HP¡¯s first all-solid-state high-end oscilloscope. Components are densely packed into the chassis and tend to run warm; cooling is important for lifetime. Make sure the fan is running well, filter is clean, all dust blown out.?

Jeremy?

On Mon, May 31, 2021 at 7:53 AM sholland via <sholland=[email protected]> wrote:
Currently eBay is showing 1804a 4 channel plugins for around $20-50. The 1804 does 4 channels but no math. The 2 channel units have addition and the specs say when one Chanel is inverted it acts like a differential input instrument! The 1821 dual time base is spectacular. It can be set up to have a variable width time delayed window within the display which is higher intensity on the screen and thus can magnify a signal within the signal. Also, a trigger can be set within that segment and a separate external trigger can be use for the main and the delayed segment. This gets you behavior like on a digital storage scope. Imaging the ability to trigger on certain glitches during the delay time. I used to use it to pluck out separate scan lines in an NTSC composite signal. Set up a separate circuit to count pulses in the signal and feed the counter output into the secondary trigger and you could pick the scan line. This is very flexible triggering.? Fun to use scope. I just picked up a 4 channel plug in and now have a 4 channel analog scope.? Screen display is rock solid when you get the trigger set up. The scope is intuitive to use. Schematics available. I think it is a great beginner scope if working. It is easy to repair with all discreet components. It has a cool feature of a signal delay line so you can see a bit of the signal before the trigger fires.

--
Jeremy Nichols
6.

--
Jeremy Nichols
6.
 

Always too many projects!?



On Mon, May 31, 2021 at 9:29 PM Dave Seiter <d.seiter@...> wrote:
I haven't looked at the 175A in about 15 years (besides as its' function as large paper weight).? Is there a better scan of the manual then the one on BAMA?? As I recall, it was very hard to read at the time.? The main reason I shelved both it and the 18x was the two pallets of mostly Tek gear I got shortly thereafter.? ?The 7104s and 7844s in particular where much more fun to deal with, especially since they are considerably lighter!? I only got two plugins with the 175A, and I'd remember if it had four channels.? I'll eventually get back to them, but I need to make room first and dispose of many other things.

-Dave

On Monday, May 31, 2021, 08:58:30 PM PDT, Jeremy Nichols <jn6wfo@...> wrote:


Dave, let me know if I can help with the 175A power supply; the low-voltage supplies are all solid state (except for one VR tube) and fairly simple. I have a working 175A and a parts unit. I¡¯m looking for a 1754A 4-channel vertical plugin for this ¡®scope.?

Jeremy?



On Mon, May 31, 2021 at 7:05 PM Dave Seiter <d.seiter@...> wrote:
I picked up one of the 180 series and a small pile of plugins many years ago, and while I was very excited at the time, I soon lost interest because everything was flaky, and was poorly engineered (in my opinion). I guess I was expecting 7603 quality, but I've never seen a working Tek scope with that many issues.? The only other HP scope I have is a 175A, which needs power supply work, I've kept it because it's anchoring (literally) the bottom of a relay rack stacked with much lighter gear.? Maybe someday....

-Dave

On Monday, May 31, 2021, 08:04:26 AM PDT, Jeremy Nichols <jn6wfo@...> wrote:


HP-180-series ¡®scopes have passed through my hands but I¡¯ve never collected one. They were HP¡¯s first all-solid-state high-end oscilloscope. Components are densely packed into the chassis and tend to run warm; cooling is important for lifetime. Make sure the fan is running well, filter is clean, all dust blown out.?

Jeremy?

On Mon, May 31, 2021 at 7:53 AM sholland via <sholland=[email protected]> wrote:
Currently eBay is showing 1804a 4 channel plugins for around $20-50. The 1804 does 4 channels but no math. The 2 channel units have addition and the specs say when one Chanel is inverted it acts like a differential input instrument! The 1821 dual time base is spectacular. It can be set up to have a variable width time delayed window within the display which is higher intensity on the screen and thus can magnify a signal within the signal. Also, a trigger can be set within that segment and a separate external trigger can be use for the main and the delayed segment. This gets you behavior like on a digital storage scope. Imaging the ability to trigger on certain glitches during the delay time. I used to use it to pluck out separate scan lines in an NTSC composite signal. Set up a separate circuit to count pulses in the signal and feed the counter output into the secondary trigger and you could pick the scan line. This is very flexible triggering.? Fun to use scope. I just picked up a 4 channel plug in and now have a 4 channel analog scope.? Screen display is rock solid when you get the trigger set up. The scope is intuitive to use. Schematics available. I think it is a great beginner scope if working. It is easy to repair with all discreet components. It has a cool feature of a signal delay line so you can see a bit of the signal before the trigger fires.

--
Jeremy Nichols
6.

--
Jeremy Nichols
6.

--
Jeremy Nichols
6.
 

Currently eBay is showing 1804a 4 channel plugins for around $20-50. The 1804 does 4 channels but no math. The 2 channel units have addition and the specs say when one Chanel is inverted it acts like a differential input instrument! The 1821 dual time base is spectacular. It can be set up to have a variable width time delayed window within the display which is higher intensity on the screen and thus can magnify a signal within the signal. Also, a trigger can be set within that segment and a separate external trigger can be use for the main and the delayed segment. This gets you behavior like on a digital storage scope. Imaging the ability to trigger on certain glitches during the delay time. I used to use it to pluck out separate scan lines in an NTSC composite signal. Set up a separate circuit to count pulses in the signal and feed the counter output into the secondary trigger and you could pick the scan line. This is very flexible triggering. ?Fun to use scope. I just picked up a 4 channel plug in and now have a 4 channel analog scope. ?Screen display is rock solid when you get the trigger set up. The scope is intuitive to use. Schematics available. I think it is a great beginner scope if working. It is easy to repair with all discreet components. It has a cool feature of a signal delay line so you can see a bit of the signal before the trigger fires.

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