Author Topic: Tektronix 485 vs 2465B  (Read 9649 times)

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Offline rhb

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Tektronix 485 vs 2465B
« on: June 22, 2018, 10:51:29 pm »
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.
 

Online tggzzz

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Re: Tektronix 485 vs 2465B
« Reply #1 on: June 22, 2018, 11:33:10 pm »
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.
There are lies, damned lies, statistics - and ADC/DAC specs.
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Offline KE5FX

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Re: Tektronix 485 vs 2465B
« Reply #2 on: June 22, 2018, 11:45:15 pm »
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.
 

Offline David Hess

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Re: Tektronix 485 vs 2465B
« Reply #3 on: June 23, 2018, 12:05:20 am »
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.
 

Offline rhb

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Re: Tektronix 485 vs 2465B
« Reply #4 on: June 23, 2018, 02:49:33 am »
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. 
 

Online tggzzz

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Re: Tektronix 485 vs 2465B
« Reply #5 on: June 23, 2018, 06:46:38 am »
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!
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
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Online bd139

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Re: Tektronix 485 vs 2465B
« Reply #6 on: June 23, 2018, 07:26:25 am »
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.
« Last Edit: June 23, 2018, 07:28:33 am by bd139 »
 

Offline G0HZU

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Re: Tektronix 485 vs 2465B
« Reply #7 on: June 23, 2018, 10:04:37 pm »
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.
« Last Edit: June 23, 2018, 10:14:16 pm by G0HZU »
 

Online bd139

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Re: Tektronix 485 vs 2465B
« Reply #8 on: June 23, 2018, 10:12:09 pm »
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.
 

Offline G0HZU

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Re: Tektronix 485 vs 2465B
« Reply #9 on: June 23, 2018, 10:24:15 pm »
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.
 

Online bd139

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Re: Tektronix 485 vs 2465B
« Reply #10 on: June 23, 2018, 10:31:05 pm »
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.
 

Offline nctnico

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Re: Tektronix 485 vs 2465B
« Reply #11 on: June 23, 2018, 10:33:14 pm »
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.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline G0HZU

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Re: Tektronix 485 vs 2465B
« Reply #12 on: June 23, 2018, 10:53:52 pm »
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.

Quote
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  ;D
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.
 

Offline David Hess

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Re: Tektronix 485 vs 2465B
« Reply #13 on: June 24, 2018, 12:09:28 am »
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.

 

Offline G0HZU

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Re: Tektronix 485 vs 2465B
« Reply #14 on: June 24, 2018, 12:59:51 am »
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.:



« Last Edit: June 24, 2018, 01:05:29 am by G0HZU »
 

Offline rhb

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Re: Tektronix 485 vs 2465B
« Reply #15 on: June 24, 2018, 01:15:53 am »
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.
 

Online Specmaster

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Re: Tektronix 485 vs 2465B
« Reply #16 on: June 24, 2018, 01:40:52 am »
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.

Quote
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  ;D
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.
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Offline KE5FX

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Re: Tektronix 485 vs 2465B
« Reply #17 on: June 24, 2018, 01:45:24 am »
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.

« Last Edit: June 24, 2018, 01:46:55 am by KE5FX »
 

Offline rhb

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Re: Tektronix 485 vs 2465B
« Reply #18 on: June 24, 2018, 03:22:56 am »
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.
 

Offline David Hess

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Re: Tektronix 485 vs 2465B
« Reply #19 on: June 24, 2018, 06:33:14 am »
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.

Quote
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.
 

Offline nctnico

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Re: Tektronix 485 vs 2465B
« Reply #20 on: June 24, 2018, 09:21:44 am »
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.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Online BravoV

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Re: Tektronix 485 vs 2465B
« Reply #21 on: June 24, 2018, 09:42:32 am »
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 ?

Online bd139

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Re: Tektronix 485 vs 2465B
« Reply #22 on: June 24, 2018, 09:57:10 am »
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  :palm: ... that eBay seller no longer exists thank goodness. The guy was a liability.
 

Offline nctnico

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Re: Tektronix 485 vs 2465B
« Reply #23 on: June 24, 2018, 10:08:18 am »
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.
« Last Edit: June 24, 2018, 11:00:25 am by nctnico »
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline chris_leyson

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Re: Tektronix 485 vs 2465B
« Reply #24 on: June 24, 2018, 11:20:50 am »
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.
 


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