Best 100MHz analogue oscilloscope?
 

I have several oscilloscopes, but my go-to is a Tektronix TAS250 which is a bit poorly but otherwise does what I need.

I'm thinking about replacing it, if I specify a used 100MHz analogue oscilloscope for a hobby workshop, which would not disappoint? Budget wise, I'm a Yorkshireman, so as cheap as possible, but I'll pay good money for the right thing!

Re: Best 100MHz analogue oscilloscope?
 

Hi!

If you're happy with an ordinary plain vanilla analogue one, why not get another 465 or 465B ?

Admittedly the internal access and repair is grotesque, but there's tons of spares and I'm sure other members'll be able to come up with spare bits!

(I appreciate it's a bit morbid to say so, but they do come up from time to time very cheaply, often when an amateur or hobbyist with one unfortunately passes on, these often go a lot cheaper than the silly overpriced offerings by T & M or commercial vendors! That's how I got many of my cheapie ones in my collection!)

Performance wise, the triggering on the 465/465B is excellent, they have a very bright, (altho' not the finest of traces as they use an expansion–mask CRT), most of the circuitry is well known, understood and reliable!

Items likely to need replacement are:–

a) Power Supply Electrolytics on Main Board A4, special little Adapter PCBs are now offered by various sellers to allow the fitting of standard 10 mm pitch PCB electrolytics without making a mess of the original PCB;

b) Attenuator leaf switches need cleaning, the procedure has been documented on here a number of places;

c) Overloading the inputs can damage the little plug–in DIL format attenuator modules, but these are used in a number of Tek 400 series and 7000 series scopes, I believe members can supply a few spares!

The 465B is the better of the two as this meets the 100 MHz bandwidth easily with a bit to spare, the earlier 465 doesn't always do so!

Chris Williams

Re: Best 100MHz analogue oscilloscope?
 

Hi!

As a PS to the above, the available 465B pdf books have been incomplete for many years, but thanks to efforts by Member "Dickie" Richard and others on the "dxdevs" Repair Site, all the missing tables and missing circuit/layout diagrams 4, 6, 9 and 10 is now freely available online!

I recommend QService's 465B Manual CD – buy the one identified as "465B LOW and HIGH Serials", then you have both variants!

Unfortunately I found the quality of the Artek one, which I bought at Christmas, disappointing!

Chris Williams

Re: Best 100MHz analogue oscilloscope?
 

I don’t think you can really go wrong with an analog scope from Tek or HP. However I have wasted countless hour keeping these things up and running as they are getting old now and parts failure are common. In my opinion scope are horrible things to work on and the 465 especially. You may already have one but I’m going to commit the ultimate sin and say just buy a new rigol or siglent. If you haven’t tried a modern scope you will love the measurement feature and the warranty. Let the roasting commence!

Re: Best 100MHz analogue oscilloscope?
 

Don't underestimate the HP 1740A

It has a few things going for it.

1) Internal access is a whole world easier than the Tek 465/465B

2) No HP scope has ever triggered on any waveform ever, just check the internet! Remind the seller of this and you can haggle him down to pennies.

3) No fan noise... no fan... importantly no need for a fan. Runs cool.

4) Switched 50 Ohm terminations on both channels.

5) Everyone I've had comfortably exceeds bandwidth spec.

6) ECL trigger logic, no tunnel diodes.

David

Re: Best 100MHz analogue oscilloscope?
 

It all depends on whether you enjoy repairing old 'scopes. For some it's part of the hobby.

I've shifted my position over the years. I've owned Tec 465's (etc) and kept them working. At the time when digital 'scopes were pretty grim, they were definitely worth considering .... even with the diabolically bad internal layout and lack of serviceability ease.

However, now digital 'scopes have come on in leaps and bounds and decent performance has descented down from instruments costing many thousands to instruments more affordable to the hobbyist. Unless you enjoy fiddling with old scopes, I would at least take a look at affordable digital scopes.

Re: Best 100MHz analogue oscilloscope?
 

If you really want an analogue scope, and I have much sympathy for you in that (I still turn to a good analogue scope before a digital one for debugging) how about the Tektronix 2445? The 24xx series are considered by many to be the pinnacle of portable analogue scope design. There are many models in the series, the 2445 having 150MHz bandwidth and the 2465 300MHz+. They have lots of useful features, the cursor measurements are good, and they're reliable. Stories abound on the Internet of people dealing with capacitor failures in their 2465Bs, but there's a simple solution to that: don't get a 2465B. The earlier 2465, for example, doesn't have failure-prone capacitors. The 2445 will be similar.

I keep a 2465 in the loft in our house in the UK to use when I'm here. I bought it in about 2004 from M&B Radio in Leeds and I've literally never had the covers off it. Last June I visited for the first time in 18 months because of the pandemic. Got the scope, switched on, no problem. This week I pulled it out again after another 6 month break - works perfectly, everything still accurate. Not bad for a 35-year-old scope. Of course, with equipment this old, anything could happen, but the fundamental design of the 2465 seems very solid.

Chris

Re: Best 100MHz analogue oscilloscope?
 

You must have got lucky & got a Tek 2465 without RIFAs :devil: in the PSU or a Schaffner line filter, I think one of mine didn't have them.
Also the Sprague electrolytics (alu can with red seals) in the PSU like to leak corrosive electrolyte, maybe yours has a different brand fitted. ???

Anyone that does re-cap the PSU of a 2445/2465 series scope should note one of the manuals has an error, two capacitors are swapped on the diagram, if followed you end up with a low voltage capacitor fitted to a high voltage rail, with resulting smoke, this was covered in an eevblog video a few years ago where this happened.

David

Re: Best 100MHz analogue oscilloscope?
 

the Tek 2245A which is 100MHz and 4 channels is quite nice to use although 2 CHs are only really for logic levels.

I got a 2445B as a non worker, plugged it in and switched it on and was delighted with the bright display before the Rifas said no ( I know I should have checked first but there you go) I changed the Rifas but still have to fix the original fault. it's only got 200 hours run time on it ( ex mod) so it will be nice when it's done. frequency counter on CH1, cursors etc.

I got a 2232 which is rather nice for 100 quid. analogue 2CH but with basic ( these days) digital storage. drives like a 'real' scope. another bargain was a TAS485. 4CH 200MHz but menu driven. the only problem with all these scopes on a day to day basis is the fan noise...

Re: Best 100MHz analogue oscilloscope?
 

I second Radio Wranglers comments re the HP 1740A plus has a max sensitivity of 1 mV/div at 40mHz b/w, excellent triggering plus all the other bits. Upgraded from an HP 180 that but the dust.


John

Re: Best 100MHz analogue oscilloscope?
 

I have three Tek 24xx series scopes in various places. I think they've all got the infamous Rifa exploding capacitors in. They've all gone snap-crackle-pop at various points in the past and I've done precisely nothing about it, just left them. The dirty secret is that they continue to work just fine afterwards so, until one of the injured capacitors breaks down and starts tripping circuit breakers or I have some weird EMC conducted emissions problem from their power supplies, it's just not worth the trouble of fixing them. They've all been in that state for about 10 years, in frequent (professional) use.

Let the Rifas do the sweating, not you.

Chris

Re: Best 100MHz analogue oscilloscope?
 

it was one of the Rifas in the snubber networks that went on mine which blew the mains fuse, and burnt a 27 ohms resistor plus the board which was a bit annoying. quite a lot of disassembly required to get the board out so while I was there I changed all the Rifas plus the some of the electrolytics

Re: Best 100MHz analogue oscilloscope?
 

Thank god for Rifa capacitors they have secured me many cheap spares or repair test gear from eBay. Got to love an easy fix

Re: Best 100MHz analogue oscilloscope?
 

I like to say the best 100MHz scope is a 200MHz scope (or faster),
this means also the both probes. So your unit works at 100MHz not at the end of the street

Tek 475 will do that, or one of the old 7704 frames with 7A26

greetings
Martin

Re: Best 100MHz analogue oscilloscope?
 

Philips made a lot of nice 'scopes.

The PM3267 has traditional knobs and buttons, but not the crispest CRT.

Later ones had the pushbutton+LCD interface, but really sharp CRTs.

Later still moved from brown to white cases, and there was a move to buttons+rotary encoders, with the on-screen text replacing the LCD. Some of these were badged Fluke. Some models were 4 channel, some went to 200MHz, and some were "CombiScopes". I have a PM3380A, which is a 2 channel, 100MHz analogue/digital unit, and love it. The worst thing I can find to complain about it is the slightly noisy fan.

I also have a PM3295, which is a 350MHz beast. There was a later A model that went to 400MHz. Obviously aimed at the Tek 2465 models. Personally, I prefer the Philips. It has a nicer user interface (buttons with status LEDs built in and little backlit LCD displays above the rotaries, so you don't have to rely on the on-screen text) and a much sharper CRT (21kV acceleration voltage!).

I have the use of many Tek 'scopes at work, including some quite posh ones, like the 2465B, but I genuinely prefer the Philips equivalents. I've never had a custom part fail in a Philips before, but we've had several Tek modules go bad over the years.

Philips use similar inline filters to Tek, so expect them to let go in the usual way. I wouldn't ignore one that's done its work though - I don't imagine the deposits left behind are very nice (happy for someone to set me straight on that - I wasn't great at chemistry!).

I've spent over a decade - on and off - trying to restore a HP1740A. Still not quite there. A donor machine helped a lot, but I keep running out of enthusiasm to finish it. The trouble is, once done, it will be bigger than my other 'scopes, and no more capable. I agree that it's much easier to work on than the Tek equivalent, and being fanless is an important benefit. In fact, that's why my "daily driver" is still - after 30+ years - a Telequipment DM63. If I need more bandwidth, I'll use the PM3295. If I need storage, I'll use the Rigol DS1054 (which is now 100MHz, though quite a bit more in practice if you measure it). But the added bandwidth comes with all sorts of complications if you want to use probes, as alluded to above...

Re: Best 100MHz analogue oscilloscope?
 

I use the Tektronix 2465 which is a fantastic scope.
*BUT* it contains digital electronics (no signal processing though) and mine has now lost some bits from the ROMs so has to be started using the "override" to the error that is flagged, at which point I find a bit or two missing from the on-screen characters.

Before that I had Tektronix's amost 100MHz lightweight portable ;D;D;D, the 585A
This was a great scope too and no problems fixing it. Nothing digital and all very spread out for easy access. But you had to be careful to use the correct funny solder and lifting gear helps.
The main snag was that in summer you risked problems from sweat dripping into things, but in winter it doubles as a fan-heater :-D

Re: Best 100MHz analogue oscilloscope?
 

here is the 15th of Heerenveen :beer:

Re: Best 100MHz analogue oscilloscope?
 

-No need for a fan heater in Martin's workshop..

Re: Best 100MHz analogue oscilloscope?
 

Ah but if you opt for a separate fan heater and oscilloscope, you can turn the heater off in summer.

David

Re: Best 100MHz analogue oscilloscope?
 

Nobody likes Hamegs?

We have a couple of Hameg 1505s at work, typical CRT / analogue Hamegs running at an untypical 150MHz (The rest of our Hamegs are run of the mill 20MHz models).

Re: Best 100MHz analogue oscilloscope?
 

Hello Martin,

Tek 585A: #1249 is greeting #15, please see attached photo.

Honestly speaking, I would not recommend a 585A for everyday use now. I still admire the very bright and clearly displayed picture but there are so many rare, sensible and expensive components that can and will become defective sooner or later. I'd rather prefer to keep it on the shelf for occasional use only.
As Stan Griffiths has mentioned: "The man who has a Tek "5s" scope in use will inevitably own a second one to be able to service the main scope"!

So, for everyday use, I'd rather opt for the suggested HP 1740 or any similar one, said it has got a good pedigree.

Re: Best 100MHz analogue oscilloscope?
 

That is somewhat true. For fixing the 585A I had their other sub-miniature offering, the 549 storage scope. The badwidth always seemed better than the quoted figure but not so high as the 585A. But I never actually needed a scope to fix the 585A as it hardly ever broke and only with "typical" faults like main electrolytic problems and one valve did blow its heater.

Re: Best 100MHz analogue oscilloscope?
 

I write this while next to an R7704. It's probably my favourite scope, but the fan is incredibly noisy! (not sure if the non-R is as noisy?). The R variant is also famed for being difficult to service, so I am hoping mine doesn't give up the ghost!

I also second the Hameg suggestion - they just keep on going. I would also check out Trio / Kenwood - they tend to be supremely reliable, and have a sharp trace.

Re: Best 100MHz analogue oscilloscope?
 

I like the Tek 22XX series scopes relatively easy to fix apart from the PSU, very light and use very few custom parts. I currently use a 2235 and also a Hitachi V1065A both 100Mhz but the Hitachi uses a lot of push buttons whereas the Tek is very conventional rotary controls. I have had many scopes in the past and have found the Japanese built ones to be the most reliable.
For the 2225 see here for info https://www.youtube.com/watch?v=8GR_6QH3uZk

Re: Best 100MHz analogue oscilloscope?
 

you know triple nickel ?
here are two of them, beside a 551 ;D

Re: Best 100MHz analogue oscilloscope?
 

I have fixed quite a few 22xx series Tek scopes presenting as dead. The psu is fragile - it is a two-stage switchmode. In the ones I fixed, the first stage produces 42V and the clever stuff in the second stage produces the various operating voltages from 42V. So the solution to a burned out first stage is to put in a cheap (£7!) Chinese 42V switchmode psu from Ebay. One of those ones that is plastic-cased, like an external laptop supply. Job done, without finding or fault-finding proprietary switching transformers or FETs.
-Jeremy

Re: Best 100MHz analogue oscilloscope?
 

Hi,

For me 465 is one of the best oscilloscope for me.
This is my oscilloscope that I use by default, when memory is nor required ( 95% of the time).
I have also a 22xx series but psu is failed and no time to repair it for the moment.
I have bought a HP1740 for lowprice, but not tested for the moment.

The problem with Tek scope is that they use custom components... still possible to buy at high price! I dont know the situation with HP or Philips?

Jean-Louis

Re: Best 100MHz analogue oscilloscope?
 

Tektronix 7603 with 7A18 (for ~75MHz) or 7A26 (for ~100MHz) amplifiers - if you can find one at a LOW price. And you have the room! They made this model for 20+ years so there are a few around. Its also the slowest of the series so prices are not as bad as the others. Avoid the 7A13 diff-amplifiers.

The tubes do not have a super sharp trace but it does have a large screen. Yes, they are absolutely packed with custom silicon but nothing with particular reliability issues. I think the channel switches can be destroyed by hot-plugging (so don't!) and I've had a single failure in a V-out IC. But there are dipped tants on board :) Not the easiest things to repair, the amplifier / timebase modules can be a disassembly challenge and the 'backplane' is tricky to get at. The PSU is modular, and linear, though it doesn't exactly fall out by itself :) There is usually a fan, but its not shifting a lot of air.

dc

Re: Best 100MHz analogue oscilloscope?
 

Another vote for the Tek 465B; I first came across 465's in the early 70's when they were the bee's knees but it wasn't till 20 years later that I was able to afford a secondhand one!

The only repairs I have done is replace the rear feet/cable tidies which disintegrated a few years ago, fortunately there is a guy on ebay in the US that supplies very good replacements. Some say they are a pig to service, but at least it's possible, and spares are available, unlike the digital scope I also have which if it fails will probably be irrepairable.

Re: Best 100MHz analogue oscilloscope?
 

Or could it be just 35MHz? Forgive me for being mischievous but I spotted an image in the news today where Angela Merkel visited Max Planck to look at their quantum research work.

On the equipment racks I spotted several of what appear to be new 35MHz Hameg 303-6 analogue scopes. These were connected up as part of a monitoring system.

https://pasquans.eu/german-chancello...visit-the-mpq/

In the background there appears to be a digital scope in use as well.

Re: Best 100MHz analogue oscilloscope?
 

Hameg oscilloscopes, endorsed by knobtwiddler and Angela Merkel. It doesn't get any better than that ;D

The Tek 7603, with its lovely big screen, has a lower acceleration voltage than the smaller 7000 scopes such as 7904 / 7854 etc. Consequently, they have sharper traces. I got a 7623 off a member here and it's razor sharp and generally a good workhorse (it's not as sharp as my baby Kenwood - nowt is as sharp as that).

Attenuator switches can be an issue with Tek 7000s. They might need a clean.

Re: Best 100MHz analogue oscilloscope?
 

hey jeremy,

you have to understand they use this 303 scopes bc. the old Tek from them is now part of my collection. ;D

Re: Best 100MHz analogue oscilloscope?
 

My favourite is my 454A but it is getting a little long in the tooth and currently only 1 channel works. It is has a very bright and sharp trace and is capable of single shot traces at very high speeds. The triggers (when working!) are also remarkably stable. This is another that needs a 2nd scope to keep it going.

Re: Best 100MHz analogue oscilloscope?
 

Thank you all for your recommendations, each of which I studied and made comparisons. I bought a Tektronix 2465 which improves on my specification - it's a 300MHz oscilloscope. Why this one? Because it was less than £200, it's four-channel, 10kg lightweight, and I've been quite fond of my Tektronix TAS220 which is a cheap Tek....

Re: Best 100MHz analogue oscilloscope?
 

I'll see your 15th of Heerenveen,
and raise you my 7th of Guernsey!