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Re: 1502 TDR
Here are a couple of things you can see with a 1502, e.g. SMA connector discontinuities 2-3cm apart.
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It also discusses the "architecture" and shorting strap, with a picture "researched" from tekwiki. On 21/11/21 06:01, Harvey White wrote:
The 1502 uses a tunnel diode, and the waveform looks like a step.? You look down the road to see what happens.? However, the 1502 has a range that is 1/10 that of the 1503, and thus increased resolution for short cables. |
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Re: You never know where Tek stuff will show up
Well said, I couldn't agree more.
-Dave -------------- What will live on? One's kindness, compassion, caring and love. It will be un named but it's influence can be far greater than we can imagine. For we ourselves are a product of our forebears and strangers in our ancestors past. |
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Re: 1502 TDR
The 1502 uses a tunnel diode, and the waveform looks like a step.? You look down the road to see what happens.? However, the 1502 has a range that is 1/10 that of the 1503, and thus increased resolution for short cables.
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The 1503 has 10 times the range (in cable terms) as the 1502, and some varieties are adjustable for different propagation factors in the cable.? Instead of a tunnel diode, it uses (IIRC) a transistor in avalanche mode to generate a sin-squared pulse (I think).? The display presentation is quite different.? The sine pulse fits more of the classic "send the pulse down the line" concept. If you compare the two, you will see that the measurement scales are different, and the catalog describes the 1503 as a "long distance" cable measurement instrument. From what I can see of the use, the 1502 was used for shorter cable runs, say from room to room, and the 1503 was used (by cable companies) for checking neighborhood (and longer) cable runs, say to 50,000 feet, perhaps. A good look at the catalog pages can give a better idea of what Tek thought of the particular uses. The Tek WIKI has some limited information on both.? The TD pulser may have been used in only the plain 1502 and not the 1502B or 1502C. I have both the 1502 and 1503, but the non B and non C versions. Harvey On 11/20/2021 11:11 PM, Greg Muir via groups.io wrote:
I wholly agree with Tom Gardner¡¯s comments. Playing with the BNC connector may be converting the 1502 into a parts unit. Besides, the 1502 was designed for a specific purpose and Tek engineers designed it to those criteria. Trying to improve its performance to a higher level that I don¡¯t quite understand why you may be trying to make a dragster out of a utility vehicle. That¡¯s why Tek came out with the 1503 to improve measurement specifications and protect the pulser from ESD. |
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Re: 7000 test/cal module(s) and backplane breakout board.
On Wed, Jul 28, 2021 at 04:52 PM, Ke-Fong Lin wrote:
Hi Ke-Fong Lin : I recommend you put this observation in your github page or (preferable) update your KiCAD files. I got the boards made in June and had to get a fresh set made with the correct dimensions (I learnt to edit the KiCAD files after waiting for some months for you to update them). The board are very nicely done but this measurement is a showstopper as it is not possible to manually align the connectors inside the 7000 mainframe unless your head is small enough to fit in! btw I also widened the edge connector contacts a bit in the version I made. Thanks for the good effort and making your design public! Best - Ram |
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Re: TEK 468 - intensity issue
Martin,
I forgot to say that if your scope and any other Tek. items have any 151-0367-00 transistors, check them. These are likely leaky from C to E as a diode. Any of these that have round leads will be leaky. Replace the leaky ones with KSP10BU. These have a pinout of BEC. I have found that leakage to cause problems until they were replaced. Mouser has these transistors. Mark |
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Re: 1502 TDR
I wholly agree with Tom Gardner¡¯s comments. Playing with the BNC connector may be converting the 1502 into a parts unit. Besides, the 1502 was designed for a specific purpose and Tek engineers designed it to those criteria. Trying to improve its performance to a higher level that I don¡¯t quite understand why you may be trying to make a dragster out of a utility vehicle. That¡¯s why Tek came out with the 1503 to improve measurement specifications and protect the pulser from ESD.
I have located faults in several mile runs of telco cables that transitioned between aerial and buried with accuracy to a foot or few to the fault using a Tek 013-0169-00 balanced output isolation transformer connected to the output of a 1503 TDR. I have both 1502s and 1503¡¯s. I seldom use the 1502s. I also have a couple of Cabletron TDR5000 TDRs that are unbelievably quite accurate even though the Cabletron company simply made them out of modified old Philips PMxxxx series oscilloscopes. But all of these are used on simple wiring, not coax. I use FFT DTF for very accurate coax cable fault location. Greg |
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Re: You never know where Tek stuff will show up
On Sat, Nov 20, 2021 at 07:45 PM, stevenhorii wrote:
If you don't already know of this effort - you may enjoy reading this and from there connect with people who surely would appreciate that equipment and have motivation and qualification to do something appropriate with it: |
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Re: TEK 468 - intensity issue
Martin,
The high brightness is likely bad d-c restorer diodes being leaky. Replace them with 1N4937. Also replace the 22meg 1/4W carbon resistor near that circuit with a Vishay VR37. This is a 1/2W 1% type. The original is highly likely high in resistance. When this resistor is high in value, the trace will be bright then dim as it warms up over 10-20 minutes without touching the intensity control. The 15V regulated supply at 22V is likely a shorted series pass transistor, Q701. It could be a bad IC, U712B. also replace the zener, VR725 with a BZX85B9V1 (this type is VERY likely open) and change R726 to a 6200ohm 1% 2W type (about 16mm or larger length). The original resistor is 1/2W and likely burned, brown body, and out of tolerance. I have seen this resistor in this circuit bad enough times to change it on sight. Mouser has the parts, except for the 6200 ohm 2W resistor. That is available on ebay. Mark |
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Re: You never know where Tek stuff will show up
Seems as though some young person could go out to gather up estate
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equipment for free and put it into a warehouse to be sold at a fair price to needy technical people. Nothing should end up in landfills, but this is happening now on a daily basis. On Sat, Nov 20, 2021, 19:08 John Williams <books4you4@...> wrote:
Good advice all. Thanks. The sad thing is I collected a lot of this stuff |
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Re: You never know where Tek stuff will show up
Good advice all. Thanks. The sad thing is I collected a lot of this stuff to save it from the fates you have described. But now after I am gone to who knows if it could meet the same fate. I remember seeing all the stuff Deane Kidd had in his house and on his property. I feared that it would mostly wind up in a landfill. I wonder what has happened to it.
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Re: You never know where Tek stuff will show up
Ken mentioned mentoring someone younger. For me, not mentoring so much as
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providing equipment to work on. Over the years, I accumulated quite a few Tek scopes. Not nearly as many as some of you and mostly the solid-state stuff (7000-series). I had earlier 500-series (545, 585, 547, 556). The 556 got sold off at a hamfest. The others I donated to the radiology department where I worked, but I suspect they wound up getting scrapped. I was moving from NY to Maryland and just did not have the space (or the lab) where I moved. I am sorry just as much for the PDP-8 and LINC-8 I had to leave behind - they were given to me but there was no way to move them or where to put them if I did. I have visions of them in the dumpsters as well (this was before they separated out "e-waste"). No one wanted them in those days. Anyway, I bought an R7844 from a guy on eBay, and rather than have him ship it when I discovered he was a relatively short drive away, I offered to pick it up. He turned out to be a very bright high school student who repaired a lot of test equipment on his own and then sold it. He had built an enviable shop for himself. He still lived with his folks in what had been an industrial building so there was much more power available than in a typical residence. After speaking with him and his folks, he seemed like an ideal candidate to take my Tek stuff that I know I will not have the time to fix or calibrate. He got two lots - he and his father came to pick them up; they needed a pickup truck. I kept a 7704A that works and I have a bunch of plug-ins for it. Plus I kept the R7844 since I bought it from him in working condition. I have some later TDS3000 series and I will likely donate the ones I don't use (the physics lab where I worked will take one). I've kept the TDS3054C. This young man is now in college studying (what else) engineering and computer science. He sells the equipment he fixes and it helps pay for his education (though he got a scholarship - having extra money as a college student is always a plus as many of you likely remember). I've done the same thing with microscopes. I donated a couple of vintage Leitz scopes to a not-for-profit mycology study and research group. I gave an older one to a technologist with whom I worked since her girls were always wanting to look at things "close up". It was set up as a student microscope so it wasn't very fussy to use. She sent me a photo of them in their princess outfits looking through the scope - I got a kick out of that. I still have a lot of microscopes, one of which is a rare model (a Zeiss Axiomat - the thing is huge and does not look like a microscope). The Walter Reed Army Medical Center has a microscope museum but they don't have an Axiomat, so one (yes, I have more than one) will go to them. Then there is my space program stuff. Most of it was bought as surplus 30 - 40 years ago when the Apollo program ended and NASA told the contractors that they could dispose of the stuff - that which had not been requested by museums or universities or then sold at GSA sales - some even came out thorough the old US surplus property disposal program. I used to get stacks of catalogs in the mail every week and knew which bases would get space program stuff. I've donated some, given away a couple of pieces, and sold some off (at a spectacular profit - on which I have to pay taxes). If any of you is interested, just look at the RR Auction sales. I think there is a "Technology" sale coming up in December; there will be some space program stuff in it. I have some rare bits - the Apollo Command Module guidance system hardware (yes, including the computer and the DSKY) but my intention is to donate that as I'd like to keep it together and make it available for future STEM-interested kids to be able to see and no sit in some billionaire's office somewhere. My wife's greatest fear is that I will pass away and leave her still with a basement full of stuff. Some of it she knows about and knows the value, but the rest? I will at least try to let her know someone knowledgeable to contact. If you find it depressing to see Tek and other fine test equipment wind up in landfills or scrap metal piles, I have stories about space program hardware that are simply heartbreaking. Steve Horii On Sat, Nov 20, 2021 at 7:41 PM Ken Eckert <eckertkp@...> wrote:
I am part of the majority here that is aging out and pondering what to do |
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Re: You never know where Tek stuff will show up
From dust we came, to dust we return. I look at all the engineering marvels
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that we marvel at, the Pyramids are one. The recording of any of the labourers is zero. In one hundred years, for most of us the same will be true. What will live on? One's kindness, compassion, caring and love. It will be un named but it's influence can be far greater than we can imagine. For we ourselves are a product of our forebears and strangers in our ancestors past. On Saturday, November 20, 2021, Dave Seiter <d.seiter@...> wrote:
I had a great aunt, who was widowed, and only had one son, who died |
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Re: 1502 TDR
Neat.? I didn't know that they did that (and don't remember words to that effect that they did....)
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That being said, I had one that I bought that had the TD assembly removed completely. Wonder what they did? Harvey No safety procedures are proof against dedicated stupidity. On 11/20/2021 7:16 PM, Tom Gardner wrote:
On 20/11/21 23:36, Reginald Beardsley via groups.io wrote:The specs indicate a BW of 2.5 GHz. However, the BNC front panel connector is a significant limitation.The 1502's BNC is, or should be, "magic". |
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Re: You never know where Tek stuff will show up
I should mention that I do not consider myself a collector.? I do not have (some exaggeration here) spotlights pointing at pristine equipment sitting on a turntable behind glass.? I have the Tektronix stuff I do because (admittedly) it was cheap, I knew what it was, some of it I saved from the shredder, and, perhaps most importantly:? I can use it.)
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The stuff I have, I use, or have available to use.? Since I don't do RF, I have no spectrum analyzers, GHZ generators, GHZ counters, etc.? Since I do a lot of digital at moderate speeds (less than 500 MHz, call *that* moderate), I have tools to do that, as well as GP analog and other digital. I deal with microprocessors, microcontrollers, power supply design, lots of programming, displays, FPGAs, packet communications, and the like. I have what I need, and in some cases, I have what I like (or want). But when I downsize, perhaps in a few years, some of it has to go somewhere.? I still want enough goodies to be able to maintain what I have for the next 20 years or so. Enter the conundrum. Harvey On 11/20/2021 7:41 PM, Ken Eckert wrote:
I am part of the majority here that is aging out and pondering what to do |
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Re: You never know where Tek stuff will show up
I had a great aunt, who was widowed, and only had one son, who died young.? Years ago when she died, the family was going through her stuff, and there where tons of photos, documents and the miscellaneous contents of a cottage to deal with.? My grandmother recognized only about 3 people in all those photos, so the entire pile went to the trash (minus about 5 photos).? Same with the documents.? The contents of the house were donated to various charities, as she didn't have anything that was interesting or valuable.? Basically, her life just vanished except for a few dozen pictures of her and memories of about 10 people.? That number is now about 6.? Kind of sobering.?
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-Dave On Saturday, November 20, 2021, 12:56:54 PM PST, byterock@... <byterock@...> wrote:
That's just messed up! -Dave Hide quoted text No I understand fully.? Just did the same with my Dad's estate except it was 30000+ photos of aircraft and 200+ books on aviation plus a very large pile of articles and documents.? My brother was just going to trash the whole lot of them, and he is an airline pilot. I saved at least the book, gave them to his flying club and an few Air Cadet Sqrd.? and saved a few of the more rare documents. Both my brother and my wife said the same think.? That was dads life not mine. Remind me to pre-arrange the disposal of my rater small shop ;) |
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Re: You never know where Tek stuff will show up
"My question then is this. What should those of us with large collections
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of Tek and other electronic equipment do while we are standing? I have over 50 scopes, a large collection of rare cameras, and other collections. I really don¡¯t know what to do so whoever survives me would be able to get these sold in such a way to keep them safe. Any suggestions? Thanks." If you don't want to leave your collection to chance, then you need to put in your WILL what is to be done with it or whom it is to go to. Just as you would your home, automobiles, guns or other valuable property. You should also name the executor of your estate in your Will and you should make your wishes known to them beforehand. All of that said, make your Will CLEAR including full names, and relationships if possible, have it witnessed by a couple of reputable people, notary publics if necessary, and have it legally recorded in your county seat. A lot of the equipment that is owned by the local hams ends up getting donated to the local ham club and they sell it off at the various hamfests. But beware, in one club I was in the president and her husband took everything that was donated and kept it for themselves so if you do want to donate to a club or a museum or ?? then you need to specify how it is to be handled. A friend of mine has added me to his Will. His wife is the executor but she knows nothing about electronics so hs's asked me to advise her on what his stuff is and what it's worth and where to best sell it. On Sat, Nov 20, 2021 at 6:58 PM John Williams <books4you4@...> wrote:
My question then is this. What should those of us with large collections |
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Re: 1502 TDR
Thanks for the valuable information, Tom. It tells us that replacing the bnc with an sma would not necessarily be a welcome improvement.
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Cheers Tom Sent from my iThing, so please forgive brevity and typos On Nov 20, 2021, at 16:16, Tom Gardner <tggzzz@...> wrote:On 20/11/21 23:36, Reginald Beardsley via groups.io wrote:The 1502's BNC is, or should be, "magic". |
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Re: You never know where Tek stuff will show up
I am part of the majority here that is aging out and pondering what to do
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with one's "stuff".... Part of the angst is when to let go. Too young and you spend time wondering what to do, leave it too late, there is the difficulties involved with trying to deal with one's hobbies when there is not the time, energy or mental ability to do so. In some ways mentoring a younger sprog is always an option for successorship......... Ken On Sat, Nov 20, 2021 at 4:11 PM Harvey White <madyn@...> wrote:
You have little control over things once you're out of the picture. |
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Re: 1502 TDR
On 20/11/21 23:36, Reginald Beardsley via groups.io wrote:
The specs indicate a BW of 2.5 GHz. However, the BNC front panel connector is a significant limitation.The 1502's BNC is, or should be, "magic". As Harvey White noted, the TD can be killed by static in a cable. Tek's solution was to have a shorting bar in the BNC socket. Before the cable is fully inserted into the BNC socket, the bar will short the cable's centre conductor to the cable's shield, thus dissipating the static before the cable is connected to the TD. Presuming the bar is working correctly, with no cable connected the display should show a short pulse corresponding to the 72mm inside the 1502 between the sampling diode and the shorting bar. It follows that you should not * connect an inter-series adaptor to the 1502's BNC * then connect the cable to the adaptor since the adaptor will open the shorting bar rendering it useless when a cable is attached. |
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Re: You never know where Tek stuff will show up
You have little control over things once you're out of the picture.
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Things very much depend on the reason you have this equipment. Collector of rarities? Perhaps give to museum or other such collectors. Got it to use it? Perhaps reduce the fold to some parts units and then working units, allowing other parts units to go to existing collectors. Perhaps sell the working units you don't need. Keep the rarities if you want. Got it to keep it out of the scrap bin? Fix as desired, and then give away to others as desired. Not that I'd be in any of these situations. Harvey On 11/20/2021 6:58 PM, John Williams wrote:
My question then is this. What should those of us with large collections of Tek and other electronic equipment do while we are standing? I have over 50 scopes, a large collection of rare cameras, and other collections. I really don¡¯t know what to do so whoever survives me would be able to get these sold in such a way to keep them safe. Any suggestions? Thanks. |
Gary Robert Bosworth
John Williams
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