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Re: Tek Scopes found in old picture book
I had dismissed the notion that this was picture of a vacuum tube computer when I first saw the image, partly because of the description of the contents of the book ("How the Microchip is Changing Our World" sure doesn't seem like the place for a picture of a vacuum tube based device), and partly because I misinterpreted what I saw on the computer screens in the background. Now it seems obvious that the computers were running software to either emulate or monitor a Williams tube. In any case I must (publicly) admit to being spectacularly wrong about the picture in a private conversation: I had expected that this was an image of a radio astronomy lab, or maybe a radio or microwave transmission facility.
Also, I had assumed that the CRT we see in the foreground was for a Tek 500-series scope, but now it seems like it is probably the replacement for the Williams tube display, which makes more sense of why it would be just sitting there, naked like that. -- Jeff Dutky |
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Re: TM5xx extenders
I have now examined several 7000-series plug-ins as well, and they do not appear to be beveled either, nor do they show obvious signed of being "rolled". I'm not saying that this was not done, just that it's not obvious to casual inspection (or inspection with a 30X loupe).
Again, I have not actually measured anything with calipers or micrometer, but everything I've looked at looks like an unmodified PCB edge. -- Jeff Dutky |
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Re: 5642 rectifier tubes in a Tek 535: Replace or swap for silicone?
Dick
With the price of NIB 5642's going for around $5
on that auction site, why bother with Solid State devices ? 73, Dick, W1KSZ ________________________________ From: [email protected] <[email protected]> on behalf of Michael A. Terrell <terrell.michael.a@...> Sent: Wednesday, July 28, 2021 10:00 AM To: [email protected] <[email protected]> Subject: Re: [TekScopes] 5642 rectifier tubes in a Tek 535: Replace or swap for silicone? I bought a reel of 5000 - Vishay HER105-T High Efficiency 400V 1A DO41 Diodes, a couple years ago for under $23. On Wed, Jul 28, 2021 at 12:34 PM Tom Lee <tomlee@...> wrote: A series string of UF4007s with a 10kV breakdown voltage would have of |
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Re: Tek Scopes found in old picture book
Oh, it's off to the right.? Had to scroll over there.? Yep, it looks just like an SS-5706.? (Now, where is that face-palm emoji when I need it?)? ? ? ? ?JimSent from my Verizon, Samsung Galaxy smartphone
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-------- Original message --------From: Tom Lee <tomlee@...> Date: 7/28/21 10:44 AM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] Tek Scopes found in old picture book Did you look online at any pics of the SS-5706? Looks like a pretty close match to me.-- Prof. Thomas H. LeeAllen Ctr., Rm. 205350 Jane Stanford WayStanford UniversityStanford, CA 94305-4070 7/28/2021 10:26, Jim Ford wrote:> Hmmm, I'm not seeing anything that looks like any of the Iwatsu scopes I'm familiar with.? I used to have 3 of them; can't remember model numbers, but they did have 60, 100, and 250 MHz bandwidths.? ?The 60 MHz one had a DMM and frequency counter on top.? Obviously copied from Tek 400 series scopes, but why own Iwatsu when you could own Tek?? So I sold them all and bought several Tek 7000 and 5000 series scopes. :)? ? ? ? ? ?Jim Ford?Sent from my Verizon, Samsung Galaxy smartphone> -------- Original message --------From: Tom Lee <tomlee@...> Date: 7/28/21? 9:30 AM? (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] Tek Scopes found in old picture book Offhand, I'd say that it is an Iwatsu, maybe an SS-5706.Tom-- Prof. Thomas H. LeeAllen Ctr., Rm. 205350 Jane Stanford WayStanford UniversityStanford, CA 94305-4070 7/28/2021 09:11, Carsten Bormann wrote:> On 2021-07-28, at 17:02, Dave Peterson via groups.io <davidpinsf@...> wrote:>> And are those 400 series scopes I see hints of (blue screens) on the far right of the racks?> My brain tells me that I saw Hamegs in the rack when I visited seven years ago.>> My picture at is not clear enough to read what¡¯s on the scope in the rack; it doesn¡¯t shout ¡°Hameg¡± at me either.> It doesn¡¯t look to me like a 475 or some such.>> Gr¨¹?e, Carsten>>>> >>>> >>
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Re: Tek Scopes found in old picture book
Well, the SS-5706A I saw online looked like one of my old Iwatsus on steroids! I didn't catch anything like that in Carsten's photo, but then I'm viewing it on a tiny smartphone screen.? Oh well.Sent from my Verizon, Samsung Galaxy smartphone
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-------- Original message --------From: Tom Lee <tomlee@...> Date: 7/28/21 10:44 AM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] Tek Scopes found in old picture book Did you look online at any pics of the SS-5706? Looks like a pretty close match to me.-- Prof. Thomas H. LeeAllen Ctr., Rm. 205350 Jane Stanford WayStanford UniversityStanford, CA 94305-4070 7/28/2021 10:26, Jim Ford wrote:> Hmmm, I'm not seeing anything that looks like any of the Iwatsu scopes I'm familiar with.? I used to have 3 of them; can't remember model numbers, but they did have 60, 100, and 250 MHz bandwidths.? ?The 60 MHz one had a DMM and frequency counter on top.? Obviously copied from Tek 400 series scopes, but why own Iwatsu when you could own Tek?? So I sold them all and bought several Tek 7000 and 5000 series scopes. :)? ? ? ? ? ?Jim Ford?Sent from my Verizon, Samsung Galaxy smartphone> -------- Original message --------From: Tom Lee <tomlee@...> Date: 7/28/21? 9:30 AM? (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] Tek Scopes found in old picture book Offhand, I'd say that it is an Iwatsu, maybe an SS-5706.Tom-- Prof. Thomas H. LeeAllen Ctr., Rm. 205350 Jane Stanford WayStanford UniversityStanford, CA 94305-4070 7/28/2021 09:11, Carsten Bormann wrote:> On 2021-07-28, at 17:02, Dave Peterson via groups.io <davidpinsf@...> wrote:>> And are those 400 series scopes I see hints of (blue screens) on the far right of the racks?> My brain tells me that I saw Hamegs in the rack when I visited seven years ago.>> My picture at is not clear enough to read what¡¯s on the scope in the rack; it doesn¡¯t shout ¡°Hameg¡± at me either.> It doesn¡¯t look to me like a 475 or some such.>> Gr¨¹?e, Carsten>>>> >>>> >>
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Re: Tek Scopes found in old picture book
Did you look online at any pics of the SS-5706? Looks like a pretty close match to me.
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-- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 7/28/2021 10:26, Jim Ford wrote:
Hmmm, I'm not seeing anything that looks like any of the Iwatsu scopes I'm familiar with.? I used to have 3 of them; can't remember model numbers, but they did have 60, 100, and 250 MHz bandwidths.? ?The 60 MHz one had a DMM and frequency counter on top.? Obviously copied from Tek 400 series scopes, but why own Iwatsu when you could own Tek?? So I sold them all and bought several Tek 7000 and 5000 series scopes. :)? ? ? ? ? ?Jim Ford?Sent from my Verizon, Samsung Galaxy smartphone |
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Re: Tek Scopes found in old picture book
Hmmm, I'm not seeing anything that looks like any of the Iwatsu scopes I'm familiar with.? I used to have 3 of them; can't remember model numbers, but they did have 60, 100, and 250 MHz bandwidths.? ?The 60 MHz one had a DMM and frequency counter on top.? Obviously copied from Tek 400 series scopes, but why own Iwatsu when you could own Tek?? So I sold them all and bought several Tek 7000 and 5000 series scopes. :)? ? ? ? ? ?Jim Ford?Sent from my Verizon, Samsung Galaxy smartphone
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-------- Original message --------From: Tom Lee <tomlee@...> Date: 7/28/21 9:30 AM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] Tek Scopes found in old picture book Offhand, I'd say that it is an Iwatsu, maybe an SS-5706.Tom-- Prof. Thomas H. LeeAllen Ctr., Rm. 205350 Jane Stanford WayStanford UniversityStanford, CA 94305-4070 7/28/2021 09:11, Carsten Bormann wrote:> On 2021-07-28, at 17:02, Dave Peterson via groups.io <davidpinsf@...> wrote:>> And are those 400 series scopes I see hints of (blue screens) on the far right of the racks?> My brain tells me that I saw Hamegs in the rack when I visited seven years ago.>> My picture at is not clear enough to read what¡¯s on the scope in the rack; it doesn¡¯t shout ¡°Hameg¡± at me either.> It doesn¡¯t look to me like a 475 or some such.>> Gr¨¹?e, Carsten>>>> >>
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Re: 5642 rectifier tubes in a Tek 535: Replace or swap for silicone?
I bought a reel of 5000 - Vishay HER105-T High Efficiency 400V 1A DO41
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Diodes, a couple years ago for under $23. On Wed, Jul 28, 2021 at 12:34 PM Tom Lee <tomlee@...> wrote:
A series string of UF4007s with a 10kV breakdown voltage would have of |
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Re: 7000 test/cal module(s) and backplane breakout board.
I see that, thanks - I'm going to take a look at the schmitt trigger input
circuitry with diode clamps you use and experiment some. Need to look at the trade-offs between the two approaches, I always relish having options to consider. In my experience any adequately interesting engineering problem contains trade-offs that take time to consider, the no-brainer decisions are not really the interesting problems. Appreciate the discussion, I do think that creating a modern toolkit to keep 7000 (and possibly 5000) mainframes in top working order without relying on a diminishing pool of original cal fixtures will pay off. I do not feel any responsibility to create the one-and-only-perfect-fixture, but am excited that as a community we can have a set of proven circuits that can be mixed-and-matched, improved, tweaked, etc. On Wed, Jul 28, 2021 at 11:31 AM Ed Breya via groups.io <edbreya= [email protected]> wrote: OK, I managed to scan my old readout exerciser schematic, posted here:-- Andy |
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Re: 5642 rectifier tubes in a Tek 535: Replace or swap for silicone?
A series string of UF4007s with a 10kV breakdown voltage would have of the order of 1pF capacitance.? The problem with 1N4007s is with their slow reverse recovery (hence the UF4007 recommendation). But reverse recovery is distinct from junction capacitance.
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Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 7/28/2021 09:29, greenboxmaven via groups.io wrote:
The idea of replacing tube rectifiers in TVs and other CRT devices is an old one. One of the most important considerations is the capacitance of the reverse biased diode. The higher the current capacity of a silicon rectifier, the higher the capacitance. Many TVs would have serious horizontal linearity issues as well as reduced high voltage when a solid state rectifier was substituted.? A string of 1N4007 diodes would likely have too much capacitance, especially at the 40 KC or higher frequency a scope high voltage supply usually operates at. A high voltage rectifier has several carefully designed and/or chosen junctions in series to share the reverse voltage, 1N4007 diodes may not balance their reverse voltage sharing properly. They are almost always used with balancing resistors in high voltage power supplies. |
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Re: 7000 test/cal module(s) and backplane breakout board.
OK, I managed to scan my old readout exerciser schematic, posted here:
/g/TekScopes/album?id=266548 Now I'm remembering some details. I had to do some tricks to skip certain parts of the code table and functions, so only the character set would show. It does not test any of the other RO functions. For a universal type interface/test setup, you'd want to have all of the code table available, using the full current ranges. Another reason to use IC DACs, is that you can include the provision for limit testing. Rather than just the nominal current steps from a 4-bit DAC, with say 8 bits, you could tweak the values around to check where the readout decides the values. Ed |
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Re: Tek Scopes found in old picture book
Offhand, I'd say that it is an Iwatsu, maybe an SS-5706.
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Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 7/28/2021 09:11, Carsten Bormann wrote:
On 2021-07-28, at 17:02, Dave Peterson via groups.io <davidpinsf@...> wrote:And are those 400 series scopes I see hints of (blue screens) on the far right of the racks?My brain tells me that I saw Hamegs in the rack when I visited seven years ago. |
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Re: 5642 rectifier tubes in a Tek 535: Replace or swap for silicone?
The idea of replacing tube rectifiers in TVs and other CRT devices is an old one. One of the most important considerations is the capacitance of the reverse biased diode. The higher the current capacity of a silicon rectifier, the higher the capacitance. Many TVs would have serious horizontal linearity issues as well as reduced high voltage when a solid state rectifier was substituted.? A string of 1N4007 diodes would likely have too much capacitance, especially at the 40 KC or higher frequency a scope high voltage supply usually operates at. A high voltage rectifier has several carefully designed and/or chosen junctions in series to share the reverse voltage, 1N4007 diodes may not balance their reverse voltage sharing properly. They are almost always used with balancing resistors in high voltage power supplies.
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??? Bruce Gentry, KA2IVY On 7/28/21 11:45, saipan59 (Pete) wrote:
Just wondering: Is it feasible to replace a 5642 with a string of (for example) cheap 1N4007's? |
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Re: Tek Scopes found in old picture book
On 2021-07-28, at 17:02, Dave Peterson via groups.io <davidpinsf@...> wrote:
My brain tells me that I saw Hamegs in the rack when I visited seven years ago. My picture at is not clear enough to read what¡¯s on the scope in the rack; it doesn¡¯t shout ¡°Hameg¡± at me either. It doesn¡¯t look to me like a 475 or some such. Gr¨¹?e, Carsten |
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Re: 5642 rectifier tubes in a Tek 535: Replace or swap for silicone?
Yep. 1N400x devices are very slow to turn off; they are charge sponges that rectify as a side effect. UF4007s would be a much better choice.
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As to equalizing networks (R and/or C), if the individual rectifiers all came from the same batch, I haven't found them to be necessary. Adjacent devices from an SMD reel or strip will be from the same batch, to a high probability. The ST app note I linked to earlier has much more detailed information. Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 7/28/2021 09:04, SCMenasian wrote:
It appears that the high voltage power supply runs at ~60kHz. I wouldn't trust a garden variety silicon diode like 1N400x to hack it. Fast recovery diodes might be OK but you might need to take precautions to ensure that the high frequency voltage is distributed evenly along the string. |
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Photo 7K RO tester.BMP uploaded
#photo-notice
[email protected] Notification
The following photos have been uploaded to the 7K readout exerciser album of the [email protected] group. By: Ed Breya <edbreya@...> |
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Re: 5642 rectifier tubes in a Tek 535: Replace or swap for silicone?
It appears that the high voltage power supply runs at ~60kHz. I wouldn't trust a garden variety silicon diode like 1N400x to hack it. Fast recovery diodes might be OK but you might need to take precautions to ensure that the high frequency voltage is distributed evenly along the string.
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Re: 5642 rectifier tubes in a Tek 535: Replace or swap for silicone?
Absolutely! Silicon HV rectifiers beyond a kV or so are actually made of series strings of lower-voltage units. A clue is their much higher forward voltages (which makes them difficult to test with conventional DMMs).
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One consideration is ensuring even partitioning of the reverse voltage across the individual diodes. If the diodes all came from the same wafer, you generally won't have to worry about adding shunt resistors, especially if you're not trying to push the limits of breakdown voltage. There's a lot more detail in this app note from ST: -- Cheers Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 7/28/2021 08:45, saipan59 (Pete) wrote:
Just wondering: Is it feasible to replace a 5642 with a string of (for example) cheap 1N4007's? |
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Re: Tek Scopes found in old picture book
On 28. Jul 2021, at 09:07, Carsten Bormann <cabocabo@...> wrote: I like the large black resistors to the right of their heads. Look like oversized fuses in their holders... In the original pic I didn't notice all the tubes on top of the shelves. What are they for? Are these thyratrons? My first guess leant towards analogue computers, thinking there were operational amplifiers all over. Stupid me, I even read about that Manchester Baby some months ago. cheers Martin |
Michael A. Terrell
Martin
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