Tektronix 485 vs 2465B

[rhb]

Does anyone with experience with both of these have any comments about them?

After some "interesting" experiences with a DSO, I've decided I want a fairly high BW analog scope as a backup.  I don't care about cursors, automatic measurements, etc.  I just want a faithful analog scope.  Something I don't have to wonder if someone wrote the software correctly.  My daily drive will be a mid-range MSO for a variety of reasons.  But I'd like something which is purely analog to consult if I encounter doubts.
I'd get a 7000 series, but I just don't have the room.

The 485 meets that nicely except it has socketed transistors and those are quite problematic in humid environments.  I've been there, done that with a 465.  And there are a *lot* of transistors in a 485.

The 2465 is soldered, but it includes lots of digital foo-foo and exotic hybrids.

I'm not averse to another brand such as HP or similar.  I'm just more familiar with Tek scopes from that era.

[tggzzz]

I've got a 485, a 2465 and a 2445b (as well as a 465 and 475). The 485 is on my bench.

Why? It just feels right in ways I cannot rationally define.

I've had to recap them all, of course.

[KE5FX]

485 any day of the week, and twice on Sunday.

Microprocessors were the best thing that ever happened to analog spectrum analyzers, but the worst thing that ever happened to analog scopes.

[David Hess]

Of those series I have a 465 and 2445B.

The 485 is easier to maintain than the 2465/A/B but is of course older so more likely to have problems.  The 2465/A/B calibration procedure is not to be underestimated but for signal integrity analysis calibration is not strictly required.

I use a 7904 for my high bandwidth needs but as you point out, the 7000 mainframes take considerable space.

[rhb]

Thanks to all.  I think that settles it.  A 485 it is despite my nervousness about the sockets unless someone can make a very strong case for something from HP.  I'm expecting to pay close to  2x  of a 2465 for a refurbished 485. 

[tggzzz]

Microprocessors were the best thing that ever happened to analog spectrum analyzers, but the worst thing that ever happened to analog scopes.

That's an interesting observation!

[bd139]

Indeed. That might explain my love for the 4xx and 7xxx series but irrational fear of the 24xx.

If you can get away with 200Mhz, the 475 is a good compromise. Very few surprises and you can slide a spare one in somewhere easily.

[G0HZU]

I would recommend you play with both types to see if you like what you see...  you might not like either of them?

In my first job in the late 80s the classic Tek 465 was still a popular scope and there were dozens of them in the labs. One of the senior staff had a 2465 and he said I could use it whilst he was away on leave for two weeks (I'd have taken it anyway if I'd got there first...).

But once I actually started using it I realised how much I didn't like this scope and within hours it was back on the other bench and I was back to the 465. For me the 2465 has too many annoying lamp indicators, the trace is very fuzzy/noisy because of the bandwidth and it is much too big to fit neatly on a smallish shelf. It also feels cheap to operate with small and fussy controls. All this is fine if you 'need' the bandwidth because there aren't many alternatives but I think I'd rather have an old 350-500MHz DSO than try and live with the 2465. The 485 looks like a nice analogue scope even if it is a bit big and I'd rather take a chance on the 485 than have to sit in front of a 2465 again.

The 475 was generally disliked where I worked and the ones we had sat unloved on the shelves. The extra trace noise was just too much for most users and the 100MHz 465 was a better compromise I think. You could select reduced bandwidth for some measurements but the 465 was much more popular than the 475 back in those days.

[bd139]

I’ve had a 465, 465B and 475 next to each other and the noise was indistiguishable with 100Mhz BWL on. Above that you expect a bit more noise really.

The vertical amp in the 475 benefits from a good cleaning session on the leaf switches generally though. Crisps right up

All of them are as reliable as each other. Buy two of whatever you get.

[G0HZU]

For me the biggest disappointment was the 2465. I guess we all see different things but I couldn't live with that scope for more than a couple of hours despite the initial excitement of being the one allowed to use it for 2 weeks. I'd be willing to try a 485 if my 465 ever went BER but it looks a bit big and bulky.

[bd139]

2465 was kind of shot by HP’s digital scopes a bit IMHO. I’d rather have a 54xxx than a 2465 as an example.

I’m getting rid of my 465 at the moment. Honestly and I say this through gritted teeth; the ds1054z I bought is more useful if I want to get from A to B.

[nctnico]

What happened with my recommendation for the Lecroy LA314H  Iwatsu SS-7847A? AFAIK this one is more modern and less likely to have problems due to age.

[G0HZU]

I've not used a fast Iwatsu scope but I did like their 60/100MHz SS-571xx offerings from the 1980s. Lovely solid scopes with nice controls and very reliable.

2465 was kind of shot by HP’s digital scopes a bit IMHO. I’d rather have a 54xxx than a 2465 as an example.

A few years ago I rescued a HP54540C 500MHz DSO from the skip at work. If it was a 2465 I'd have left it there for someone else to find 
The old HP54540C isn't a very nice scope because the user interface is poor and the fan sounds like an industrial air vent. But it can behave quite well in peak detect mode when looking at modulated RF waveforms. It's generally a noisy, slow old dog but much more use than a Tek 2465 to me.

[David Hess]

For me the 2465 has too many annoying lamp indicators, the trace is very fuzzy/noisy because of the bandwidth and it is much too big to fit neatly on a smallish shelf.

The 475 was generally disliked where I worked and the ones we had sat unloved on the shelves. The extra trace noise was just too much for most users and the 100MHz 465 was a better compromise I think. You could select reduced bandwidth for some measurements but the 465 was much more popular than the 475 back in those days.

I have somewhat of the same complaint about my 100MHz 465 and 150MHz 2445B in comparison with my 100MHz 22xx series and much faster 7000 mainframes.  There is an obvious tradeoff between bandwidth and trace noise however CRT design features heavily into this.

My 465 and 2445B are neither as bright or sharp as my several 22xx oscilloscopes which I prefer to use while my must faster 7904 is both sharper and much brighter than any of them.  Part of this is due to form factor with the 7904 having an advantage because it supports a longer CRT and this is a weakness with portable high bandwidth analog oscilloscopes.

I’ve had a 465, 465B and 475 next to each other and the noise was indistiguishable with 100Mhz BWL on. Above that you expect a bit more noise really.

I was rather disappointed in the sharpness and brightness of my 465 compared to my 22xx models but after doing some work on it, it has improved so it may just be suffering from disuse.  It does show the expansion mesh pattern on the CRT unlike my 22xx models so Tektronix must have made some improvements in their CRTs between when they were made.

[G0HZU]

The sharpest CRT base scope I've owned was my very first scope. A big old Tek 585. I'm not sure if it is a genuine 100MHz scope but it is something like 85-100MHz according to various literature from Tek. It has a wonderfully crisp trace although I think there are other vintage scopes that are even better. A two tone (SSB) RF waveform looks wonderful on it once focussed sharply and it puts the 465 to shame here. The 2465 would look even worse I think. 

You can see a Tek 485 close up in action in W2AEWs old lab tour on youtube below. He seems quite pleased with the trace quality and sharpness and this is alongside what look like a couple of 2465 scopes.:

[rhb]

What happened with my recommendation for the Lecroy LA314H  Iwatsu SS-7847A? AFAIK this one is more modern and less likely to have problems due to age.

Yes, but it is a hybrid and more expensive.  I've got a line on a 485 a guy is refurbishing which he says is the cleanest one he's seen.  It is entirely analog.  I don't like the sockets, but you can't have everything.  It's important to remember that this is intended to double check when I think a DSO  might be lying to me.  It's likely to live in a Pelican case with bags of silica gel a lot of the time.

I really like my 465, though I prefer the Dumont 1060 as it has no fan.  But otherwise they are very similar.

My experience with CRTs on both  was that careful adjustment during the calibration process was quite important.  As I had to repair both, calibration was an essential step.

[Specmaster]

I've not used a fast Iwatsu scope but I did like their 60/100MHz SS-571xx offerings from the 1980s. Lovely solid scopes with nice controls and very reliable.

2465 was kind of shot by HP’s digital scopes a bit IMHO. I’d rather have a 54xxx than a 2465 as an example.

A few years ago I rescued a HP54540C 500MHz DSO from the skip at work. If it was a 2465 I'd have left it there for someone else to find 
The old HP54540C isn't a very nice scope because the user interface is poor and the fan sounds like an industrial air vent. But it can behave quite well in peak detect mode when looking at modulated RF waveforms. It's generally a noisy, slow old dog but much more use than a Tek 2465 to me.

I agree, the Iwatsu scopes are really great, I have a SS5710 (50MHz 2+2 channel) and that is just a joy to use, good feel to the controls, rock steady performance and a sharp trace and is my goto scope on my bench. I have zero knowledge of Tek scopes, never had one, always seem to steer clear of them because I keep reading about them failing and always needing attention and they roll their own bits and many of which are no longer obtainable should you want one. 

HP, I have a 1740A which I'm selling on, although it has a good crisp display, I'm always under the hood of it tinkering with all the interconnections between the boards to make it work properly when it decides to play up. I have a nice little Hitachi V525 (50Mhz) which has cursors and a mega zoom, again a brand not to be overlooked, good solid performer and a newly acquired Fluke 3390B combiscope (200MHz), all three scopes, Iwatsu, Hitachi and the Fluke are extremely good scopes and ones that I would not like to loose.

[KE5FX]

Most of the problems you'll have with the 485 will involve tantalum caps.  Not a major showstopper, but some of them are harder to reach than others.  The attenuators and 50-ohm input switches can be a bit temperamental as well, which is one area where the 2465s have always been strong,

I haven't heard a lot of complaints about transistor sockets.  There is a school of thought that advocates treating them with an expensive substance called Stabilant 22 to cure and/or prevent intermittent symptoms, but others argue that this is just so much snake oil.  Plain old DeOxit D5 is probably a safe bet, used sparingly (i.e., not directly out of a spray can.)  Leaving them alone and not looking for trouble unless/until necessary is the safest bet of all.

[rhb]

I had to go through both the Tek and the Dumont and wiggle all the transistors.  It's not an issue in a dry climate, but in high humidity it is a nightmare unless it sits powered on 24/7 or is in an environmentally controlled environment with low humidity.  God help you if it sat in a truck day and night in a humid climate.

The scope I'm  considering will have had the tantalum caps replaced and and a very thorough refurbishment and calibration. I do not expect it will be cheap, probably 2x a 2465B.  But after a few years using DSOs I don't entirely trust them.

[David Hess]

The sharpest CRT base scope I've owned was my very first scope. A big old Tek 585. I'm not sure if it is a genuine 100MHz scope but it is something like 85-100MHz according to various literature from Tek. It has a wonderfully crisp trace although I think there are other vintage scopes that are even better. A two tone (SSB) RF waveform looks wonderful on it once focussed sharply and it puts the 465 to shame here. The 2465 would look even worse I think.

The 585 like the 547 is about the last Tektronix oscilloscope to lack scan expansion.  With the exception of the 2465 series, these can be identified by looking for the absence of ghosting following and then preceding the CRT spot at low sweep speeds.  The 2465 series uses box lenses for scan expansion because otherwise the microchannel plate image intensifier in the 2467 would amplify the ghosting produced by a scan expansion mesh and wash out the display.

You can see a Tek 485 close up in action in W2AEWs old lab tour on youtube below. He seems quite pleased with the trace quality and sharpness and this is alongside what look like a couple of 2465 scopes.

The 485 like the 7904 benefits from having a higher acceleration voltage which makes for a brighter and sharper display.  Actually all of the 150MHz and faster 7000 mainframes have sharp and bright CRTs due to their 24 kilovolt CRT acceleration.

I have a nice little Hitachi V525 (50Mhz) which has cursors and a mega zoom, again a brand not to be overlooked, good solid performer and a newly acquired Fluke 3390B combiscope (200MHz), all three scopes, Iwatsu, Hitachi and the Fluke are extremely good scopes and ones that I would not like to loose.

I think Hitachi did not use scan expansion resulting in sharper and brighter CRTs than Tektronix.  Fluke and Iwatsu may have done this also.  The test described above can be used to determine this.  I have no idea about HP.

[nctnico]

What happened with my recommendation for the Lecroy LA314H  Iwatsu SS-7847A? AFAIK this one is more modern and less likely to have problems due to age.

Yes, but it is a hybrid and more expensive.  I've got a line on a 485 a guy is refurbishing which he says is the cleanest one he's seen.  It is entirely analog.  I don't like the sockets, but you can't have everything.  It's important to remember that this is intended to double check when I think a DSO  might be lying to me.  It's likely to live in a Pelican case with bags of silica gel a lot of the time.

What would worry me about buying the 485 or the 2465B is that I'll become a curator of a museum instead of a tool. I'm also very wary of people who refurbish equipment. That usually involves contact spray and due to some very bad experiences (equipment totally f**ked up) with that stuff I avoid it like the plague. Besides that some people have less skills than they are aware of and break more than fix.

[BravoV]

What happened with my recommendation for the Lecroy LA314H  Iwatsu SS-7847A? AFAIK this one is more modern and less likely to have problems due to age.

Yes, but it is a hybrid and more expensive.  I've got a line on a 485 a guy is refurbishing which he says is the cleanest one he's seen.  It is entirely analog.  I don't like the sockets, but you can't have everything.  It's important to remember that this is intended to double check when I think a DSO  might be lying to me.  It's likely to live in a Pelican case with bags of silica gel a lot of the time.

What would worry me about buying the 485 or the 2465B is that I'll become a curator of a museum instead of a tool. I'm also very wary of people who refurbish equipment. That usually involves contact spray and due to some very bad experiences (equipment totally f**ked up) with that stuff I avoid it like the plague. Besides that some people have less skills than they are aware of and break more than fix.

What made your suggested the "used" Lecroy LA314H or Iwatsu SS-7847A, differ from Tek 485 & 2465B ?

Are Lecroy LA314H or Iwatsu SS-7847A use non proprietary chips that are easily sourced ?

[bd139]

What happened with my recommendation for the Lecroy LA314H  Iwatsu SS-7847A? AFAIK this one is more modern and less likely to have problems due to age.

Yes, but it is a hybrid and more expensive.  I've got a line on a 485 a guy is refurbishing which he says is the cleanest one he's seen.  It is entirely analog.  I don't like the sockets, but you can't have everything.  It's important to remember that this is intended to double check when I think a DSO  might be lying to me.  It's likely to live in a Pelican case with bags of silica gel a lot of the time.

What would worry me about buying the 485 or the 2465B is that I'll become a curator of a museum instead of a tool. I'm also very wary of people who refurbish equipment. That usually involves contact spray and due to some very bad experiences (equipment totally f**ked up) with that stuff I avoid it like the plague. Besides that some people have less skills than they are aware of and break more than fix.

Have to agree. I tend to buy the broken ones myself and fix them because broken ones usually have less of a chance of being meddled with.

I had a 453 where someone had decided to fix the trigger by substituting the tunnel diodes with rectifier diodes and has replaced the vertical output transistors with whatever they had lying around resulting in a bandwidth of about 6Mhz  ... that eBay seller no longer exists thank goodness. The guy was a liability.

[nctnico]

What made your suggested the "used" Lecroy LA314H or Iwatsu SS-7847A, differ from Tek 485 & 2465B ?

Are Lecroy LA314H or Iwatsu SS-7847A use non proprietary chips that are easily sourced ?

It is newer and thus less likely to break down in the near future. Newer also means that it is more likely that they used off-the-shelve parts and even if there are proprietary chips it is more likely you can buy them from somewhere.

Edit: when looking for a high frequency analog scope myself I ended up with the LA314H. I also looked at the 485 and 2465B but they where more expensive and older.

[chris_leyson]

The 2465 has a mesh accelerator anode so the focus isn't as good as on the 485 or the 7000 series crts. It's difficult to describe objectively but it's a feature of the 24xx scopes that I never liked. My personal preference would be 485.

[GeorgeOfTheJungle]

My favourite is the 2232, at the flip of a switch becomes a DSO and it's got plenty of knobs and buttons including four very handy direct save/recall waveform memories.

Edit: it's only 100 MHz though.

[David Hess]

The 2465 has a mesh accelerator anode so the focus isn't as good as on the 485 or the 7000 series crts. It's difficult to describe objectively but it's a feature of the 24xx scopes that I never liked. My personal preference would be 485.

The 485 and 7000 and practically anything newer than the last of the 500 series have scan expansion meshes.  The 2465 series, 7104, and the 11302 are the exception as they have box or quadrupole lenses to allow the use of microchannel plate image intensifiers.

But scan expansion is scan expansion whether from a scan expansion mesh or box lens so they all suffer from a larger spot size.  The only model I find it actually noticeable on is my 465 and the sharpest CRT I have is naturally from my 547 with my high acceleration voltage 7000 mainframes which should perform similar to a 485 being close behind and much brighter.  My 2445B might be my "fuzziest" except for my 465 but I suspect both would improve if I used them much like my 7603 improved; CRTs left in storage for years seem to become fuzzy until powered for a couple of days.

Does any of this matter for practical use?  It might if you have a choice.  Otherwise just recognize that high bandwidth oscilloscopes like the 485 have sharper and brighter CRTs than lower bandwidth oscilloscopes like the 465.

The 100MHz 22xx models which replaced the 100MHz 465/465B seem to have better CRTs but maybe the difference is just due to age; I have seen lots of different 22xx models over a long time but only a couple of 465s for a short time.

My favourite is the 2232, at the flip of a switch becomes a DSO and it's got plenty of knobs and buttons including four very handy direct save/recall waveform memories.

I really like the 2232 also.  With peak detection it covers storage applications just fine and the storage display looks much better than one would expect because of the high resolution of the CRT.

[G0HZU]

Does any of this matter for practical use? 

It definitely mattered for me in the 1980s when I was a student as I used the old Tek 585 to help me repair/service ham/CB SSB radios to supplement my student income. The two tone response on the 585 was a class apart from a 465 and I would have refused to use a 2465 for stuff like this because the trace is so unrewarding to look at and the detail at the waveform crossover would have been lost in fuzz and noise. But then again the 2465 was a new scope and cost a fortune back then. Even the oldest and scruffiest of the 465s in M&B radio in Leeds were several hundreds of pounds in those days. I got my 585 for £70 at a radio rally and it was much better than both of these scopes for the stuff I was doing

This difference in trace quality is almost certainly why I dislike the 2465 but the other reason is all the distracting lamp indicators and the fussy little cheapo controls on the user interface. The 485 looks a much nicer scope and if it can do a 300MHz BW and still have a trace quality better than a 465 then I would definitely choose this over the 2465.

[David Hess]

This whole archived discussion thread at the TekScopes email list is worth reading but start with this message:

https://groups.io/g/TekScopes/message/107383

The design teams deployed the new scopes and put them to use. In about two months, the engineering manager of GVG had collected all of the 7704s, put them on pallets and shipped them back to Tek Beaverton. The engineers gladly reverted to their trusted 547s.

Why? - Spot size.

[tggzzz]

The 485 looks a much nicer scope and if it can do a 300MHz BW and still have a trace quality better than a 465 then I would definitely choose this over the 2465.

Well I like the 485's display, e.g. 1ns/division:

[precaud]

The design teams deployed the new scopes and put them to use. In about two months, the engineering manager of GVG had collected all of the 7704s, put them on pallets and shipped them back to Tek Beaverton. The engineers gladly reverted to their trusted 547s.

Why? - Spot size.

The 547 was my fave scope ever. I got a near-perfect one that I used until 1996, then moved and put it, several backups, and other 500-series scopes in an outdoor storage shed, where they were to sit until I retired and would rebuild. Five years ago the shed was "cleaned out" by thieves over Thanksgiving weekend. The scopes never appeared in the local market for resale. Chances are they got dismantled and sold for scrap. Lots of aluminum in those...

[David Hess]

This is my 7904 displaying both rising and falling edges at two different sweep speeds.  The transient response needs a little bit of adjusting but I need a faster source among other things to do that.

The 547 was my fave scope ever. I got a near-perfect one that I used until 1996, then moved and put it, several backups, and other 500-series scopes in an outdoor storage shed, where they were to sit until I retired and would rebuild. Five years ago the shed was "cleaned out" by thieves over Thanksgiving weekend. The scopes never appeared in the local market for resale. Chances are they got dismantled and sold for scrap. Lots of aluminum in those...

That is a shame.  It would take a lot of work to steal a bunch of heavy 500 series oscilloscopes but I have heard of weirder things being stolen.

I picked up mine through Craigslist for $50 but I could understand not wanting  to hunt another down and shipping can be literally a pain.

[mtdoc]

I own a 465b, 475, 2236, and 2467. I’m partial to the 2467:

[rhb]

The 485 looks a much nicer scope and if it can do a 300MHz BW and still have a trace quality better than a 465 then I would definitely choose this over the 2465.

Well I like the 485's display, e.g. 1ns/division:

That's a proper step response.  I'll probably tweak mine for a little less overshoot.  But the 3% on the Instek  MSO-2204EA and the 7% on the Keysight MSOX3104T are ridiculous.  Especially the latter

[med6753]

The scopes with the sharpest and best defined traces IMHO are the old Tek 500 series. Nothing comes close.

The analog scopes in my collection are a 2465, 2465 DMS, 465, OS-245 (7603N), and a B&K 2120. The 2465 twins have the “fuzzy wuzzy” traces while the others have acceptable traces. I've never seen or used a 485 so I can't comment on it. It's been at least 30 years since I used a 475 but I don't recall the trace being “fuzzy”. My first experience with a 2465 was back in the early 1990's. I had just built a Heathkit IG-4244 Oscilloscope Calibrator and I wanted to test it's high frequency response. The only scope I had at that time was the 20MHz B&K 2120. So I asked an engineer at work if I could borrow his new 2465. All the measurement parameters came out dead nuts but the trace looked like crap. I thought the scope was broken. I mentioned this to the engineer and he said “Nope, they are like that”. It certainly didn't compare to the 7904's I had used in the past. It was a real disappointment.

Most of my hobbyist stuff is low frequency so unless I need the high frequency response I keep the 20MHz b/w limiter on. That really sharpens the trace on the 2465 twins. It was mentioned that they found the 2465 “too big” compared to the 465. I have to disagree with that. They are practically the same size. In fact, the 465 weighs considerably more than a 2465 due to it's linear power supply and big iron transformer.

Should an analog scope be processor controlled? Interesting question. I think Tek engineers decided to go that route so they could pack as many features and options in the available footprint and still have a portable scope. Of course that makes maintenance/repair so much more complicated and I'm painfully aware of that. But are the controls “fussy” and cheap feeling? I don't think so. I have no problem with the layout and I find it easy to use.     

[G0HZU]

It was mentioned that they found the 2465 “too big” compared to the 465. I have to disagree with that.

It was really a works specific gripe in that the 465 fitted our shelving system at work and the 2465 didn't. I think our shelves were a standard size/height so sig gens, scopes and various meters fitted. The 2465 might have fitted if I'd removed the handle and the stuff on top but I think I'd have been in trouble with the owner

At home I was using a Tek 585 which was enormous in comparison.

I haven't used one of these 2465 scopes for many years but I do vaguely remember that the owner of that first 2465 warned me in advance about the rocker selector for 50R/1meg/etc selection. This wasn't a very precise control and it was easy to flick it to the wrong setting. Looking at later models it looks like this control was changed and it was used in a few places on the front panel.

I still think it's worth trying both the 485 and 2465 to see which (if either) are OK for your needs. For me, the human factors of a scope are very important and a typical scope session involves lots of control tweaking and so the layout and ease of use are very important compared to other test gear. Also, the build quality has to be good so the controls don't wear out or fall off and obviously, the display trace quality and triggering have to be very good. Probably the best analogue scope I've used in this respect is the Iwatsu SS5710/1 although they are quite big scopes. The 485 looks quite good to me. For, me the 2465 failed these requirements in too many places and it's a scope I've avoided ever since.

[David Hess]

The 22xx and 24xx series oscilloscopes have slightly larger footprints than the 4xx series so Tektronix had to increase the size of their oscilloscope carts from the 200 (11.5x16.5), to the 200C (12.9x17.3), to the K212 (13.0x17.3).

[rhb]

My regular scope needs to be an MSO.  I'm expecting an R&S RTM3K demo unit at any minute.  The 485 will be there primarily for one purpose, to check for ringing on GPIO traces. Whether I go through with getting a 485 in part depends upon the R&S step response.  However, I should very much like to have a fast purely analog scope, and the 485 seems to be the best fit for what I want and the space required.  So even if not needed I expect I shall get one anyway.

I had an opportunity to get one or more 475s in need of repair, but in the end passed on them because I really didn't want to repair scopes.  However, I had occasion recently to look at my 465 manual and it is so beautifully written I had some pangs of regret on passing on the 475s.

[bd139]

The manual is a pleasure. I’ve restored a few, I think 11 off 465, 465B and 475.  It’s a rewarding experience with a great outcome. These were completely dead and one was rotting when they were obtained for pittance:

[David Hess]

The 485 will be there primarily for one purpose, to check for ringing on GPIO traces. Whether I go through with getting a 485 in part depends upon the R&S step response.

Unless the R&S RTM3K is broken, the only thing which will matter for that application is bandwidth.  A used analog oscilloscope has the advantage of much higher bandwidth for a given price versus a new DSO.

[Howardlong]

The manual is a pleasure. I’ve restored a few, I think 11 off 465, 465B and 475.  It’s a rewarding experience with a great outcome. These were completely dead and one was rotting when they were obtained for pittance:

The trace rotation’s off on the 475.  ;-)

[bd139]

Haha we spotted  . They were just chucked in a pile there. In theory you should alter trace rotation when you move the things.

[David Hess]

The first photograph is the bad transient response on the 465 I am refurbishing.  Initially the CRT trace was fuzzier but it improved after a couple hours of operation and cleaning the bandwidth switch.  I suspect this instrument spent years in storage.

The second photograph is the same transient response on my 2232 which is within specifications although the 2% overshoot is missing probably indicating that it was last calibrated with a poor source or the service manual instructions were not read carefully enough.  I did not think it worth recalibrating just for that.  Notice that the 2232 trace is cleaner than the 465 trace.

The third photograph is the PG506 fast rise output used in these tests on a 14GHz sampling oscilloscope.  Ignore the pattern dependent jitter; it was a deliberate part of the test.  It looks like the RG-400 patch cable I was using might be displaying dribble up but I did not notice it at the time or I would have confirmed it.

[G0HZU]

The 465 is at best average in terms of trace sharpness but it should look better than the photo above. My 465 was last serviced nearly 25 years ago when I first bought it. I did it all myself and did as much of the stuff in the manual that I could. I think mine is a reasonably good example although it was quite badly out of adjustment when I first got it. I think it took me a couple of days to wade through the procedures in the manual.

My trace response is quite similar to the 2232 image. However, I suspect that if you put both scopes side by side the 2232 would edge it on sharpness because it's hard to take photos of CRT traces and retain the sharpness. Also the setting of the intensity control and camera settings seem to significantly affect the results with a camera. None of my cameras seem to be able to capture the CRT display without making the scope trace look fuzzy. The risetime looks very droopy on the 465 and I guess you still have this to fix. It would be nice to see the response when it is fixed. I find that the quality/size of the 50R termination affects the response a bit and mine shows a bit of excess overshoot with a cheapo (long and big) BNC 50R feedthrough.

[particleman]

The first photograph is the bad transient response on the 465 I am refurbishing.  Initially the CRT trace was fuzzier but it improved after a couple hours of operation and cleaning the bandwidth switch.  I suspect this instrument spent years in storage.

The second photograph is the same transient response on my 2232 which is within specifications although the 2% overshoot is missing probably indicating that it was last calibrated with a poor source or the service manual instructions were not read carefully enough.  I did not think it worth recalibrating just for that.  Notice that the 2232 trace is cleaner than the 465 trace.

The third photograph is the PG506 fast rise output used in these tests on a 14GHz sampling oscilloscope.  Ignore the pattern dependent jitter; it was a deliberate part of the test.  It looks like the RG-400 patch cable I was using might be displaying dribble up but I did not notice it at the time or I would have confirmed it.

David, out of curiosity is the picture of the 465 trace also 200mV/division?

[David Hess]

The 465 is at best average in terms of trace sharpness but it should look better than the photo above.

Possibly and I do not have any experience with different 465s but others have said that they were not as sharp as later 100 MHz CRTs in the 22xx series and that there was considerable variation between early 465s and late 465Bs.  Mine might just be old or have a lot of hours although the CRT does not display double peaking.

My trace response is quite similar to the 2232 image. However, I suspect that if you put both scopes side by side the 2232 would edge it on sharpness because it's hard to take photos of CRT traces and retain the sharpness. Also the setting of the intensity control and camera settings seem to significantly affect the results with a camera. None of my cameras seem to be able to capture the CRT display without making the scope trace look fuzzy.

I picked up a Canon SX150 just for taking oscilloscope photographs.  It is much better than the piece of junk Sony DSC-S70 that I used to use.  I get better exposures with relatively high ambient light levels but this makes it difficult to prevent shadows.

The risetime looks very droopy on the 465 and I guess you still have this to fix. It would be nice to see the response when it is fixed. I find that the quality/size of the 50R termination affects the response a bit and mine shows a bit of excess overshoot with a cheapo (long and big) BNC 50R feedthrough.

It is the same configuration including 50 ohm feedthrough for both photographs but something is obviously wrong with the 465.  It was even worse before I started working with it and I still need to go through the vertical signal paths in detail.

David, out of curiosity is the picture of the 465 trace also 200mV/division?

Yes, I am pretty sure it is also 200mV/div with the variable control not engaged and the pulse output adjusted at the source for 1 volt deflection.  I did not take any specific notes but that is almost always what I start testing with unless there is a problem.

Ideally this test is first done at the native 5mV/div on a 465 where none of the high impedance attenuators or collector loads are used but I checked the vertical ranges and they all worked and produced results consistent with the 200mV/div result.

I am working on rebuilding the fan and power supply first.

[BravoV]

... because it's hard to take photos of CRT traces and retain the sharpness. Also the setting of the intensity control and camera settings seem to significantly affect the results with a camera. None of my cameras seem to be able to capture the CRT display without making the scope trace look fuzzy.

2565B shot using entry level DSLR with crappy stock lens.

Is this trace considered fuzzy compared to those sharper Tek 4xx series ?

[David Hess]

It looks fuzzy to me and like my 2445B.  The 20 MHz bandwidth limit should be used for consistent comparisons.

[BravoV]

It looks fuzzy to me and like my 2445B.  The 20 MHz bandwidth limit should be used for consistent comparisons.

Ok, I believe you, and you've just made my TEA disease getting worst. 

[rhb]

This has wandered a long way from my original question, which is OK.

I received an R&S RTM3K  on demo today and  t am absolutely awestruck.  The default response is a 2-3% overshoot with a 350 pS rise time.  But if I engage the math functions and apply a 1 GHz low pass filter I get a 450 pS rise time with *no* overshoot. The input is one of Leo Bodnar's 40 pS rise time pulsers. Mine measured at 36 pS when shipped a few months ago.

It is so good, I may well decide to not get a 485. The RTM3K was clearly specified by people who used scopes every day.  After the heartbreak of a bargain  MSOX3104T, it is a welcome sign that not all is lost.

Having said that I feel obliged to note that comparing my Keysight 33622A  to a GPSDO leaves me in great awe of the designers of the 33622A.   That comparison showed that instabilities relative to my 8648C with the high stability option were the 8648C.  I've not opened up the 33622A, but so far as i know it does not have the high stability option.

[mtdoc]

2565B shot using entry level DSLR with crappy stock lens.

Ha, way better than my shakey iphone scope photography. 

Is this trace considered fuzzy compared to those sharper Tek 4xx series ?

No not IMO. Sure, an old, in need of recap scope or poorly focused CRT will be bad but otherwise analog scope traces are what they are and I don't get the obsession with slight variations.  On any scope, isn't the question whether the trace is allowing you to see what you need to see accurately? These all allow that.

he RTM3K was clearly specified by people who used scopes every day.

I feel the same way about my lower tier RTB2004. 

[particleman]

The 2465 has a mesh accelerator anode so the focus isn't as good as on the 485 or the 7000 series crts. It's difficult to describe objectively but it's a feature of the 24xx scopes that I never liked. My personal preference would be 485.

The 485 and 7000 and practically anything newer than the last of the 500 series have scan expansion meshes.  The 2465 series, 7104, and the 11302 are the exception as they have box or quadrupole lenses to allow the use of microchannel plate image intensifiers.

But scan expansion is scan expansion whether from a scan expansion mesh or box lens so they all suffer from a larger spot size.  The only model I find it actually noticeable on is my 465 and the sharpest CRT I have is naturally from my 547 with my high acceleration voltage 7000 mainframes which should perform similar to a 485 being close behind and much brighter.  My 2445B might be my "fuzziest" except for my 465 but I suspect both would improve if I used them much like my 7603 improved; CRTs left in storage for years seem to become fuzzy until powered for a couple of days.

Does any of this matter for practical use?  It might if you have a choice.  Otherwise just recognize that high bandwidth oscilloscopes like the 485 have sharper and brighter CRTs than lower bandwidth oscilloscopes like the 465.

The 100MHz 22xx models which replaced the 100MHz 465/465B seem to have better CRTs but maybe the difference is just due to age; I have seen lots of different 22xx models over a long time but only a couple of 465s for a short time.

My favourite is the 2232, at the flip of a switch becomes a DSO and it's got plenty of knobs and buttons including four very handy direct save/recall waveform memories.

I really like the 2232 also.  With peak detection it covers storage applications just fine and the storage display looks much better than one would expect because of the high resolution of the CRT.

My 485 has a very nice clear sharp trace along with my 7633 but do you know what gives them a run for their money in that department? My old 453. It has a much sharper trace than 2213A,2221,465,468.  Don't laugh, but  for the kinds of things I do that is my go to oscilloscope.

[David Hess]

My 485 has a very nice clear sharp trace along with my 7633 but do you know what gives them a run for their money in that department? My old 453. It has a much sharper trace than 2213A,2221,465,468.  Don't laugh, but  for the kinds of things I do that is my go to oscilloscope.

Smaller CRT deflection means less scan expansion yielding a sharper trace but the total area is smaller also.  Wasn't there some variation in CRTs used for the 453/453A and 454/454A oscilloscopes?

You might check to see if your 453 CRT has scan expansion at all since it is only 50 MHz.  To do this, set a slow sweep speed and watch for the "ghost" following, catching up to, and then preceding the spot across the CRT.