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Old 5th Feb 2018, 11:38 pm   #61
WaveyDipole
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Default Re: Tektronix 465 restoration

I just saw a 475 go for £360 in an eBay auction! Some one must have been desperate to own it! Maybe they thought that the sig-gen was included or got into a silly bidding war. You can get a 2465 for that! I wouldn't have minded 'upgrading' my 465, but not at that price!

Having fixed the usual shorted tants and a cracked HT cap, my 465 has served me well for a year or so now. I also replaced the incandescent backlight bulbs with 30,000 mcd white LEDs. One bulb had failed anyway. The illumination is a bit brighter and more even. I purchased a Tek 2235 from a member a while ago, but I didn't realise that there is no Gate and particularly CH1 (or CH2) signal out on the back so I can't connect the FC.

On the subject of couriers, I sent a Hameg by courier last year and thought I had packed it well, but one of the feet managed to get damaged all the same so I can understand the caution of collecting in person.

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Old 6th Feb 2018, 1:20 am   #62
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Default Re: Tektronix 465 restoration

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I’ve got a rule of never transporting a scope by courier. My tek 2225 was damaged by the courier. Managed to smash one of the moulded plastic feet to bits.
That is a good rule because: "Every stage in the shipping is equivalent to throwing the item down one flight of stairs" So shipping a scope to a calibration house has multiple risks. This is why I acquired all of the required Tek generators to calibrate my own scopes. Calibration of the 2465B requires the exact Tek generators for a good result, because of the firmware protocol.

Aside from the 2465B's, my favorite more vintage Tek scopes are the 464 and 466, because of the storage function that is great for slow events, but otherwise they are an excellent 100Mhz scope. There are two basic versions of each of these scopes, a later type with altered front panel artwork and LED indicators (vs the light pipe indicators of the earlier models) also altered vertical amplifier design with dedicated Gilbert cell IC's immediately after the input Fets. These later ones are by far the superior versions, yet ebay sellers seem unaware there are two different types of the 464 and 466, because the model number is the same, but its easy to spot looking at the front panels.
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Old 6th Feb 2018, 4:13 pm   #63
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Default Re: Tektronix 465 restoration

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I just saw a 475 go for £360 in an eBay auction! Some one must have been desperate to own it!
Recently, I bid £130 for a 466 with what I believed to be three Philips probes. My logic was £100 for the scope and £10 for each probe. I wasn't prepared to go any higher, but someone was. Can you believe it sold for £452 plus £30 delivery?! Someone really wanted it, probably more than a newer digital storage scope!
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Old 6th Feb 2018, 4:18 pm   #64
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Default Re: Tektronix 465 restoration

I would have expected most of the storage tubes to be knackered by now, they always had a shorter life than standard types.
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Old 6th Feb 2018, 6:07 pm   #65
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I would have expected most of the storage tubes to be knackered by now, they always had a shorter life than standard types.
I did not know this point. I'm not sure of the mechanism why a storage tube would fail before any other CRT, what is the reason ?

I guess in these 464 scopes, most of the time, they are not used in storage mode anyway so it might explain my experiences with them. I have three of these scopes and the CRT appears perfect in all. I also had a 4th one I sold and its CRT was also just fine.

Of my three 2465B's I replaced one CRT because the focus was just a little soft, but most people would have been happy with it.
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Old 6th Feb 2018, 6:51 pm   #66
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Default Re: Tektronix 465 restoration

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I did not know this point. I'm not sure of the mechanism why a storage tube would fail before any other CRT, what is the reason ?
Possibly the mechanism whereby the more expensive an item of test equipment is, the bigger the organisation has to be that could contemplate acquiring it, and the bigger the organisation is, the more likely it is for said equipment to be encountered by the muscle-headed and uncomprehending,

"I couldn't get a picture, so I turned every knob fully clock-wise. In the end, I got a picture, but it was very bright and didn't last very long".


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Old 6th Feb 2018, 7:22 pm   #67
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Default Re: Tektronix 465 restoration

There are various different types of storage tube but in general they are all much more complex than a standard tube and use special phosphors which are less rugged than the standard P31. My understanding is that the storage facility normally dies much quicker than standard operation.
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Old 6th Feb 2018, 9:37 pm   #68
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Default Re: Tektronix 465 restoration

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The main reason the 4x5’s get dirty inside is running them without a filter.
Cooker-hood filter media (the sort obtainable from Lakeland) seems to work well. I'd thought of cutting a green scouring pad to size - but as someone else on here pointed out, there's a risk of contamination by abrasive particulates over time.
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Old 6th Feb 2018, 11:09 pm   #69
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There are various different types of storage tube but in general they are all much more complex than a standard tube and use special phosphors which are less rugged than the standard P31.
I don't think this is the case for the particular CRT's used in the 464 and 466. The reason I say this is that it is easy to flood the screen and get a bright uniform light output. When doing that it would be easy to see areas of phosphor that had lost sensitivity with respect to adjacent areas. There are no visible areas of de-sensitization or burn on any of the CRT's in my three scopes, even in the center where one might have expected the scope to have had a relentlessly scanning beam, if it was left turned on all day.

It is true though that some CRT phosphors are much more sensitive to damage than others. Especially non- aluminized P4 types in vintage TV CRT's. Have a look at page 4 of this article, it shows a recording (from a Tek 464 in storage mode) of a turn off pulse that was created to blank the CRT beam on a 5FP4 CRT used as a substitute for the Emiscope tube in an HMV904 TV. Otherwise the phosphor aquires a central burn with time due to the intense blast of electrons when the raster collapses at turn off:

http://worldphaco.com/uploads/CONVER...A_5FP4_CRT.pdf

I find the storage function on the 464's invaluable for slow events or one off pulses & spikes. Prior to that I used the Telequipment D52 with a long yellow/short blue CRT, but the trace would often fade away before I could photograph it !

One other trick I found with the 2465B, because it has an accurately calibrated on screen trigger threshold, that can be used to measure the amplitude of an otherwise invisible (on the screen) narrow voltage spike by setting it so it just triggers.

Last edited by Argus25; 6th Feb 2018 at 11:36 pm. Reason: typo
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Old 6th Feb 2018, 11:26 pm   #70
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the more likely it is for said equipment to be encountered by the muscle-headed and uncomprehending
When someone at work reports some problem with a computer, the IT fellow here often reports back that it was a PBKC problem. "Problem between keyboard & chair". The other common one used is the "ID"-"Ten"- "T" problem, which verbalized like that doesn't sound like an insult, but when written on paper spells idiot.

Last edited by Argus25; 6th Feb 2018 at 11:33 pm.
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Old 7th Feb 2018, 12:33 am   #71
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Default Re: Tektronix 465 restoration

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Originally Posted by Argus25 View Post
Quote:
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I would have expected most of the storage tubes to be knackered by now, they always had a shorter life than standard types.
I did not know this point. I'm not sure of the mechanism why a storage tube would fail before any other CRT, what is the reason ?

I guess in these 464 scopes, most of the time, they are not used in storage mode anyway so it might explain my experiences with them. I have three of these scopes and the CRT appears perfect in all. I also had a 4th one I sold and its CRT was also just fine.

Of my three 2465B's I replaced one CRT because the focus was just a little soft, but most people would have been happy with it.

Behind the screen is a 'storage mesh' which isn't electrically one piece, it is a matrix of isolated pieces.

There are two gun in the tube. the main gun produces a focused beam which is focused and deflected in the normal way, and there is a flood gun which uniformly illuminates the non-screen side of the storage mesh with low energy electrons.

The storage mesh is charged up in such a way that the charge around each hole in the mesh pinches it off so soft electrons from the flood gun cannot get through and the screen remains dark.

Along comes the main beam and write a waveform across the storage mesh. This beam is powerful enough to overwrite the charge on the pixel areas of the mesh, and where it has written, electrons from the flood gun stream through and show th written waveform on the phosphor screen. Writing gun electros pass through the storage mesh and write a trace on the phosphor screen, and then the flood gun electrons keep the trace lit on the screen.

Eventually flood gun electrons affect the stored charge on the storage mesh, and the picture degrades. The brighter you have the flood gun, the quicker it degrades. Dark, the image can remain for days.

Variable persistence can be simulated by periodically re-initialising the storage mesh.

With the flood gun off and a suitable mesh bias, the tube can work like a normal one, but to get a bright picture the main gun beam has more current than we want for longevity of the storage mesh. The electron beam can cut the mesh into pieces. Slowly at low currents, quickly at higher currents.

The problem is that nothing shows you when you have conventional mode selected, that you have too much current on and are abrading the mesh. In storage mode, you'd see the picture bloom until you turn down the main beam current, but in conventional mode nothing shows until after the damage is done.

Good users set the beam current in storage mode to not bloom, before selecting conventional scope mode. Unwary users think this is too dim and wind the current up, damaging the mesh.

If you own the scope, you will operate it sympathetically. If it's the firms, it gets used by people who don't know and may even not care.

The vast majoriity of storage frames for spectrum analyser plug-in's I come across have been ruined.

If you want a conventional scope, use a conventional scope. Save the storage scope for when you need storage. Avoid 'conv' if you can. If you can't. set the beam current in storage mode so it doesn't bloom THEN select 'conv'. If it's too dark, hard luck, live with it.

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Old 7th Feb 2018, 3:51 am   #72
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Default Re: Tektronix 465 restoration

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If you own the scope, you will operate it sympathetically. If it's the firms, it gets used by people who don't know and may even not care.
This is very true. I treat my scopes with the utmost care and respect and always have the beam energy as low as possible to go easy on the CRT.

It has always irked me when I have walked into labs and seen scopes unattended running full beam brightness, so I rush to them to turn the intensity down and get weird looks from others thinking there was nothing wrong with the situation. But they don't own the scopes and the level of care is severely diminished. I think I said in an article once that damaging a Tek scope should be a Federal offence.

I have seen horrible damage to Tek scopes from calibration houses, screws over tightened, damaged heads, wrong tools used, adjustment C's and R's damaged, calibration stickers (my pet hate) scraped off with screwdrivers. It is sickening.
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Old 7th Feb 2018, 3:14 pm   #73
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Default Re: Tektronix 465 restoration

Excuse the bulk of relies here but have been sick for the last 3 days with vertigo and dizzy head. Fun fun fun. Has gone away now.

Quote:
Originally Posted by WaveyDipole View Post
I just saw a 475 go for £360 in an eBay auction! Some one must have been desperate to own it! Maybe they thought that the sig-gen was included or got into a silly bidding war. You can get a 2465 for that! I wouldn't have minded 'upgrading' my 465, but not at that price!

Having fixed the usual shorted tants and a cracked HT cap, my 465 has served me well for a year or so now. I also replaced the incandescent backlight bulbs with 30,000 mcd white LEDs. One bulb had failed anyway. The illumination is a bit brighter and more even. I purchased a Tek 2235 from a member a while ago, but I didn't realise that there is no Gate and particularly CH1 (or CH2) signal out on the back so I can't connect the FC.
Yes I saw that 475. I sold my two for £150 each working. One had the DM44 module as well.

I like the incandescent bulbs in the earlier 465 and 475 units. They're nice and warm looking unlike the later LEDs on the 465B. However I have noticed that the ready light is dead on my 465. I'm not annoyed enough to dig it out and replace it though. It's not critical to the function of the unit.

Channel output is one of the best features I've found on any scope. My counter lives semi-permanently hooked into it.
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Old 7th Feb 2018, 3:17 pm   #74
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Default Re: Tektronix 465 restoration

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I’ve got a rule of never transporting a scope by courier. My tek 2225 was damaged by the courier. Managed to smash one of the moulded plastic feet to bits.
That is a good rule because: "Every stage in the shipping is equivalent to throwing the item down one flight of stairs" So shipping a scope to a calibration house has multiple risks. This is why I acquired all of the required Tek generators to calibrate my own scopes. Calibration of the 2465B requires the exact Tek generators for a good result, because of the firmware protocol.
I'm working on collecting Tek calibration bits. Really want one of their time mark generators and a 191. That'll do me for my requirements. I missed one of the TMGs unfortunately as I was driving once. Went for pocket change as well
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Old 7th Feb 2018, 3:17 pm   #75
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Default Re: Tektronix 465 restoration

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If you own the scope, you will operate it sympathetically. If it's the firms, it gets used by people who don't know and may even not care.
This is very true. I treat my scopes with the utmost care and respect and always have the beam energy as low as possible to go easy on the CRT.

It has always irked me when I have walked into labs and seen scopes unattended running full beam brightness, so I rush to them to turn the intensity down and get weird looks from others thinking there was nothing wrong with the situation. But they don't own the scopes and the level of care is severely diminished. I think I said in an article once that damaging a Tek scope should be a Federal offence.

I have seen horrible damage to Tek scopes from calibration houses, screws over tightened, damaged heads, wrong tools used, adjustment C's and R's damaged, calibration stickers (my pet hate) scraped off with screwdrivers. It is sickening.
Couldn't agree more.

The cal house that last did this 465 munted one of the trimmers on the timebase. Had to replace it.
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Old 8th Feb 2018, 11:04 am   #76
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Default Re: Tektronix 465 restoration

Also agree with RR and Argus. I also try to treat my scopes with care and do not leave them on for long periods unattended. I also keep the intensity to a minimum but comfortable level. Interesting to hear about the damage caused by calibration houses. You would think they would know better! There is no excuse for causing damage to internal components or using wrong tools. If mistakes happen (as they do sometimes) then I would expect for the problem to be rectified and a report on the issue prior to the equipment being returned. Maybe that is asking too much these days!
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Old 8th Feb 2018, 11:20 am   #77
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Default Re: Tektronix 465 restoration

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Interesting to hear about the damage caused by calibration houses. You would think they would know better!
As with PAT and MOT testing, the virtually guaranteed and mandated market makes it an apparently win-win business model that attracts all sorts- but some do well and get a good reputation, others find it a struggle and the quality of staff and their work slip- but with a pious "what I decide is the law, sir...." attitude.

The comments about going round turning off un-attended 'scopes in labs strikes a chord with me. too- I hated seeing expensive tube hours being frittered. Also the 'leccy bill when we're supposed to be eco-minded. At home, I've even got into the habit of nudging the bench 'scope off-focus when I'm not actually using it. I reckon I'm with the comment about mis-use of good and pricey test-gear being an offence!

Last edited by turretslug; 8th Feb 2018 at 11:29 am.
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Old 9th Feb 2018, 10:42 pm   #78
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Default Re: Tektronix 465 restoration

Been kicking myself today. I've had a search for a Tek 2465 set up for about 2 months now and have been watching one for the last week, only to forget about the auction last night as I was out. It sold for £195 which i would have been happy to pay. One last week sold for nearly £300. Memory seems not what it used to be...
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Old 9th Feb 2018, 11:18 pm   #79
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Default Re: Tektronix 465 restoration

That is annoying.

It's quite crazy really because the Tek scopes have gone up considerably in price suddenly. I can only afford broken ones! (which is just as well as I like meddling with them )
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Old 10th Feb 2018, 12:39 am   #80
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Default Re: Tektronix 465 restoration

Not really relevant to a restoration thread, but the selling price depends on the second bidder, you don't know what the winner bid unless it was the only one.
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