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Re: 475 questions
Hi Bruce,
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Okay - I was thinking the 475's caps were the same as the 465 but perhaps not. It's a custom board I designed and had manufactured. BTW, if you notice, the board shown has a trace that had to be removed for that version of the board (I made a mistake...). I had another batch made where that wasn't necessary. Thanks, Barry - N4BUQ ----- Original Message -----
From: "ciclista41 via groups.io" <ciclista41@...> |
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Re: Encouraging beginners: What are we accomplishing?
Many enthusiastic youngsters had comparable experiences with instrument companies in the 1960s. General Electric and to a lesser degree RCA were also very kind to young hams and experimenters. I spent my youth in a place where one huge chemical plant dominated the local industries. They had an extensive outreach to youngsters showing interest in science and especially technology, it paid off for them by providing an abundance of techie kids applying for employment after graduation. This was the company that invented super glue, at the time it was still under patent and only available from them. Their recruiters always came prepared with lots of it that didn't quite measure up but was still very usable. An occasional Tektronix, General Radio, or Hewlett Packard manual would also be in their bag. None of us with "pump gas-cut grass-throw papers" money could afford anything Tektronix unless we were exceptionally lucky and it for some reason showed up at the local scrapyard that took in from many regional industries. While some of us had driver's licenses, most of us got there on bicycles or walked. One testament to the quality of equipment was how well it survived a few miles in a bicycle trailer or cart.
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Bruce Gentry, KA2IVY On 5/27/20 10:36 PM, stevenhorii wrote:
My experience with Tektronix began far before I had a Tek scope. I was |
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Re: Tek 4041 GPIB Controller
Stephen,
I think it would be pretty simple to put an Arduino board inside the 4041 case - connected to the internal keyboard header, plus my resistor mod so the Arduino could direct drive serial into the 4041. It might be easier to not worry about how long the 4041 takes to boot and just install an Arduino reset button on the back of the 4041. Press the Arduino reset button and the Arduino program would output the SET DRIVER and SET CONSOLE commands - which would require that the 4041 had the Program Development ROMs. Does everyone on this thread already have those ROMs in their ROM Carrier? Otherwise - the 4041 will only auto load an AUTOLD.IT program from tape - as the Program Development ROMs are required to run ASCII BASIC commands like SET DRIVER and SET CONSOLE. Or someone needs to disassemble the Utility ROM and figure out how to make a PROM that would hold the AUTOLD.IT program to do the serial commands. When I look at the 16-bit binary image of the Utility ROM, it looks organized similar to the Tektronix 4050 ROM packs, with a header, followed by ROM call names, each followed by the entry point address for that ROM call. In addition the last 1024 bytes of the Utility ROM look like a template for the PROM image: Offset(h) 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F 00003C00 30 2B 00 20 47 F3 00 20 2B 4B 00 24 60 AA 4E 75 0+. Gó. +K.$`?Nu 00003C10 00 00 00 00 00 06 00 10 46 4F 52 84 00 08 41 53 ........FOR?..AS 00003C20 43 FF 00 00 49 54 45 FF 01 00 45 4F 4D 01 01 11 C?..ITE?..EOM... 00003C30 45 4F 55 01 01 10 45 4F 41 01 01 0F 45 4F 48 01 EOU...EOA...EOH. 00003C40 01 0E 00 00 00 00 46 69 6C 65 20 20 54 79 70 65 ......File Type 00003C50 20 20 53 69 7A 65 20 20 20 20 43 72 65 61 74 69 Size Creati 00003C60 6F 6E 20 44 61 74 65 20 20 5F 5F 5F 5F 20 20 5F on Date ____ _ 00003C70 5F 5F 5F 20 20 5F 5F 5F 5F 20 5F 5F 5F 5F 5F 5F ___ ____ ______ 00003C80 5F 5F 5F 5F 5F 5F 5F 5F 5F 5F 5F 5F 00 00 00 00 ____________.... 00003C90 00 05 50 52 4F 4D 3A 00 00 00 00 00 00 00 00 00 ..PROM:......... 00003CA0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003CB0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003CC0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003CD0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003CE0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003CF0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003D00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003D10 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003D20 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003D30 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003D40 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003D50 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003D60 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003D70 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003D80 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003D90 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003DA0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003DB0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003DC0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003DD0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003DE0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003DF0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003E00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003E10 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003E20 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003E30 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003E40 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003E50 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003E60 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003E70 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003E80 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003E90 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003EA0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003EB0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003EC0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003ED0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003EE0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003EF0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003F00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003F10 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003F20 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003F30 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003F40 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003F50 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003F60 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003F70 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003F80 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003F90 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003FA0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003FB0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003FC0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003FD0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003FE0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00003FF0 FF FF FF FF 22 22 21 22 01 01 FE FE 3D 0F F4 20 ????""!"..??=.? |
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Re: probe.
On Thu, May 28, 2020 at 07:40 AM, James Theonas wrote:
It would be insofar as bandwidth is concerned. The transient response however is not matched to the input characteristics of the 2465B. It'll work but signal fidelity will not be optimal, resulting in visible step response artifacts. For the 2465B, Tek recommended the P6137. With the right tools and equipment, you could optimize the behavior of the probe with its high-frequency adjustments. Raymond |
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Re: probe.
This is intended for use with some TDS scopes and has a 500MHz bandwidth. So probably ok with a 400MHz scope. They also have a problem which can render them scrap. See:
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I don't have either a 2465B or a P6139A, so you can take this with a pinch of salt, except for the mentioned problem. Colin. -----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of James Theonas via groups.io Sent: 28 May 2020 06:40 To: TekScopes Mail List (New: groups.io) Subject: [TekScopes] probe. A quick question for the group. I have a 2465b and have found a p6139a locally in good condition. Is this probe a good match for my scope? Dimitris Theonas |
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Re: Tek 4041 GPIB Controller
Monty,
Good to see you have now established communication with the keyboard port. You are correct that the COMM0 port description is required for a 4041 with the dual RS232 port option. I use the same technique since my tape drive doesn't work and I have to manually enter those commands every time the 4041 is powered up to redirect the console. I been thinking of automating the process by building a small microcontroller board that emulates the keyboard and outputs the necessary commands every time the 4041 is powered on. I haven't progressed this yet as I need to do some experiments to figure out when the 4041 has completed its power-up sequence and is ready to accept keyboard commands and how fast it can process those commands. Stephen |
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Re: Encouraging beginners: What are we accomplishing?
Hello Dennis,
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Denis Cobley was his name, I spelt it incorrectly. If you look up the old messages you will find him. In regards to test equipment repairs, Magic flowed from his hands and he had an encyclopdiac knowledge of Tektronix scopes of that era. The little company, "TrioSmartcal", where he was the service manager changed its name as it merged and got absorbed by other companies. Over the years all the people that I once knew have drifted away so I do not know where Denis Cobley is today. One of the most helpful men I have ever known, I learnt a lot from him. More than a decade ago, thanks to this group, I met Denis Cobley and got a job when I needed one. That is something more than just luck! Regards, John Crighton Sydney ----- Original Message -----
From: "Dennis Tillman W7pF" <dennis@...> To: <[email protected]> Sent: Thursday, May 28, 2020 2:17 PM Subject: Re: [TekScopes] Encouraging beginners: What are we accomplishing? Hi John Thanks for the reply and the very interesting story. I feel like I know Denis Cobly from somewhere. I did a search of my email but didn't fine anything. Would you ask him if he recognizes my name, and if so, from where, Thanks, Dennis --- This email has been checked for viruses by AVG. |
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Re: 475 questions
Hi All,
I may have done this, but I don't think so: /g/TekScopes/photo/247625/0?p=Created,,,20,2,0,0. Note the cap and resistor are supposed to be soldered to one another, but the joint was broken. I soldered the leads back together, but I think I need a cylindrical crimp fitting to reduce the chance that the joint will break there again. Bruce |
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Re: 475 questions
Hi Barry,
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That certainly looks like a neat way to handle it! I've already order the disc-shaped ones for this board. As far as I know, there isn't a similar set-up available for the 475, but I like the single board with stand-offs. My 475 has six large caps there, rather than five, although I read somewhere that two of these are in parallel, so can be replaced with a single cap. Was that solution a custom job, or purchased ready made? Bruce On Wed, May 27, 2020 at 08:03 AM, n4buq wrote:
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Re: 475 questions
Hi Michael,
I had noticed that page of the manual in passing, but did not study it, as I assumed it would be following the same standard used elsewhere. Thank you for pointing out that that is not the case. I now have that page printed for easier reference in the future and have verified the correct cap rating using it as you describe. The diagram also shows the vertical stripe as indicating the positive lead. However, as you indicated, the voltage rating corresponding to the gray color of the vertical stripe is not designated in the chart. If we call it silver, rather than gray, the chart remains ambiguous as to voltage rating. I assume that since the C1304 is supposed to be 50V ±20 that that is what it is. As you said, no way to tell by looking at the capacitor, itself, though. How did you know what voltage is being used by the circuit on the A7 board? Bruce |
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Re: 475 questions
Hi Michael,
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Very good to hear that Tek has that convention, as it confirms what I thought about how these were oriented before I took them out. Experience is so very valuable when it comes to this kind of thing. Thank you very much for sharing yours! Bruce On Wed, May 27, 2020 at 07:24 PM, Mlynch001 wrote:
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Re: 475 questions
Hi Graham,
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I've taken several photos, particularly of the A8 board that I removed to get at the large caps. Forgot to do that with the A7 board, but I noted that the printing on the cap was facing the front of the scope before removal, so got away with the oversight this time. Yes, that colorful sleeping dog will remain undisturbed! Bruce On Wed, May 27, 2020 at 06:59 PM, VK1GVC wrote:
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Re: Encouraging beginners: What are we accomplishing?
Hi John
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Thanks for the reply and the very interesting story. I feel like I know Denis Cobly from somewhere. I did a search of my email but didn't fine anything. Would you ask him if he recognizes my name, and if so, from where, Thanks, Dennis -----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of John Crighton Sent: Wednesday, May 27, 2020 8:31 PM To: [email protected] Subject: Re: [TekScopes] Encouraging beginners: What are we accomplishing? Double Yikes! Hello Dennis, thanks for the huge reply, I feel bad that you have spent many hours on it. I have received your message loud and clear. Good to know that you and Chuck are still mates, he did explain that in another post. Dennis, please continue to run the group. I did not intend to undermine you. I was just mentioning something that annoyed me. The abrupt end of Chuck's explaination of how to measure Xc using a scope. Just when his electronics lesson was getting interesting the whole discussion was stopped. OK, I accept your reasons. You said, "TekScopes is about classic Tektronix test equipment, its use, repair, and collecting". I believe in that too. About 15 or 16 years ago, on this group, I asked some dumb questions about the air filter or lack of one, on my newly aquired 454 oscilloscope. Someone in the USA offered to send me some filter material. How Generous! A Mr. Denis Cobly, an ex Tektronix employee piped up on this group and said he was in Sydney also and I should call into "Trio Smartcal" and pick up filter material rather than let a Tekscope group member in USA send it to me. I found out that "Smartcal" was a little company set up by ex Tektronix workers when Tektronix folded in Sydney. Some time later the name changed to Trio Smartcal. I got to know Mr Denis Cobly by asking dumb questions and buying junked items. Out of the blue one day he offered me a temporay job. I was in heaven, surrounded by Tektronix people and Tektronix equipment. Mr Denis Cobly explained that I was to look after "the junk" leaving his experienced boys to the more complex items that came in for repair and calibration. One day a 475 scope landed on my bench. It came in a specially built Aluminium container with Qantas Airline calibration labels on it. It was in mint condition, no signs of use. I was given a check list to test the scopes performance but no adjustments to be made. It was explained that this scope was priceless as the aircraft makers specified this particular model 475 had to be used. Like I said before, I was in heaven. The ex Tektronix engineers around me were so helpfull in teaching me how to use the TM500 series instruments used to check this 475 scope. Dennis, repair of old test equipment and learning along the way is what I like to do. Bruce is struggling to repair his 475 scope on the "475 questions thread" Ex Tektronix people helped me with a 475 scope years ago. I support Bruce in fixing his 475 scope even though the thread is long and boring to some people on the group. I hope I have explained where I am coming from. Regards, John Crighton Sydney ----- Original Message ----- From: "Dennis Tillman W7pF" <dennis@...> To: <[email protected]> Sent: Thursday, May 28, 2020 10:54 AM Subject: Re: [TekScopes] Encouraging beginners: What are we accomplishing? YIKES! Hi John, I would like to make amends for anything I said to Chuck. I have known him as a contributor to TekScopes for the past 17 years. I consider myself fortunate that he has shared his experience and observations as a member of other groups with me. We communicate with each other regularly off list. He was planning to stop for a visit until the virus put everything on hold. Only Chuck can say if your characterization is correct. Chuck is not shy so if he has something to say I know he will :) If possible put yourself in my shoes for a minute. Two weeks ago on TekScopes several important issues were conflated and I was suddenly feeling a lot of stress while I tried to sort out how best to proceed. The ESR Meter thread resurfaced once again and I requested that the participants consider the impact on our other members if they continued. I find it ironic that you just clearly expressed your preference that the recent 475 thread be allowed to continue ad infinitum by taking issue with Roy Thistle. You singled out the one individual who, like you with the 475 thread, was a participant in the lengthy ESR thread until Roy took charge of the issue by creating a new ESR Forum on 开云体育. That relieved some of the pressure I was feeling from members. Once again, Thank You Roy! Some members saw ESR Meters as a legitimate Tek related topic since they are a troubleshooting tool. Other members thought this topic was not specific enough to TekScopes and requested I stop it. My responsibility is to choose between them. Fortunately I didn't have to because Roy Thistle took charge and created an ESR Forum on 开云体育. Chuck and I have both been around long enough to remember teletypes. So it was not really an issue when I saw the "character sketch" he included in an email describing own to make an engineer's ESR Meter. I watched as one member after another asked what that pile of hieroglyphics was supposed to be. A few people understood it and provided an explanation. The explanations resulted in still more questions/confusion which required even longer explanations. Chuck and I both find it strange that something so simple could cause so much confusion. I realized everyone needed instructions on how to decipher it. So I provided the instructions to understand what Chuck had drawn. The issue of allowing attachments generated a lot of polarized responses pro and con. Some of the responses were verging on rude which surprised me. I have no experience with attachments and out of personal ignorance I thought about all the things that could go wrong. I needed to learn more about attachments ASAP and I started to do just that. I think Chuck must have sensed I was confused and having a hard time with this because he contacted me and made many good suggestions about where I should go and who I could discuss my concerns with to learn more. Attachments have benefits and they have drawbacks. I have seen some of the benefits. I am still waiting for answers about how to eliminate or minimize the drawbacks. I spent many hours today writing this reply to you (this is the third time I wrote it, starting over from the beginning each time) because a brand new issue appeared yesterday which has all the makings of a controversy that is going to be a whopper. A few days ago I couldn't help but notice the "475 Questions" thread was getting very long. It is currently at 148 posts. I took a look at a few of the posts and I was stunned to see a member ask what "exp" meant. I couldn't spend much time thinking about it because yesterday a member got right to the core of that issue when he posted this new topic "Encouraging beginners: What are we accomplishing?" Apparently his question is not easy to answer to everyone's satisfaction. One more thing before I'll permit you to step out of my shoes: All of these issues have generated a lot of comments that are taking a huge amount of my time to respond to. That is less time I have to get the answers to the whether to enable attachments I have asked of other group moderator/owners. That was the hot issue 2 weeks ago. That is how far behind I am. I will probably choose to ignore this new topic until I reach a conclusion on the previous hot topic. Out of necessity I may stop responding entirely until I catch up. If you, John, would like to take my place in the interim please feel free. A few things to remember if you do: TEKSCOPES GOAL (from Michael Dunn in 2000): "TekScopes is about classic Tektronix test equipment, its use, repair, and collecting". THE GOLDEN RULE FOR GROUPS (from Stefan Trethan in 2018): “No politics, no religion, no sports, simple as that.” THE MODERATORS JOB IS TO STOP THIS PATTERN BEFORE IT REACHES #5 1. A slightly OT post is made. 2. It generates an unusually large number of responses. 3. This generates even more comments that go off at tangents. 4. Someone asks that the participants bring it under control. 5. That request creates more posts in support of the original slightly O.T. post. 6. Someone replies with "if you don't like it use your delete key" 7. That results in comments pro and con about whether the original post was O.T. 8. The posts die down over the next week. 9. If they don't die down the moderator will ask that the topic be put to bed. TEKSCOPES IS NOT A SALES SITE: EBay, Craigslist, etc. are the proper place to list items you have for sale. However if you are offering our members scarce parts, sub-assemblies, instruments, etc. at prices that our members can afford then it makes perfect sense to offer them on TekScopes. Dennis Tillman W7pF -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of John Crighton Sent: Tuesday, May 26, 2020 10:04 PM To: [email protected] Subject: Re: [TekScopes] Encouraging beginners: What are we accomplishing? Hello Roy, I am really surprised at you of all people sounding like a wet blanket. The owner of this tekscope group told you in no uncertain terms if you want to talk about ESR Meters to go and form your own group. Which to your credit you did just that. I also did not like the way that the owner of this group, Dennis Tillman, jumped on Mr Chuck Harris for describing how to use an oscilloscope with a function generator to check capacitors for value and ESR. Shutting someone up for describing how to use an oscilloscope on an oscilloscope group is to me just plain crazy. Those are rules that you have to obey, like them or not. Roy, if you are not enjoying reading about the repair of the 475 scope by a beginner then do not read the thread. It is that simple! I think it is marvellous that so many people on this group are willing to help an individul fix his 475 scope. What a great thing to do, while we are in corona virus lock down. My fellow countryman Graham VK1GVC, down in Canberra is doing a great job helping Bruce and so so are all the othere people. The side benefit for me and no doubt others on this group is that Bruce is asking basic questions as a beginner that other people on this group might not dare to ask for fear of looking foolish. Keep asking questions Bruce. I want you to fix this scope. Regards, John Crighton Sydney ----- Original Message ----- From: "Roy Thistle" <roy.thistle@...> To: <[email protected]> Sent: Wednesday, May 27, 2020 1:51 PM Subject: [TekScopes] Encouraging beginners: What are we accomplishing? Hi all TekScopers: Reading through a long thread, recently posted, caused me to wonder.. just what are TekScopers accomplishing with threads like this... and why are we encouraging someone who is "... new to electronics..." to dig into a 475?.. one of the most complex, and compact, analog instruments ever designed. I suppose.. in consideration... Michael discouraged the use of a Mr. Carlson super Weller-kluge special, on the 475's pcb(s)... but, ya know... somewhere the thread... the 475 owner hints he paid 20.00 for 475?, and he's also got a nonworking? PM3218 too. So why didn't someone just recommend/... right off the bat... to take the 475 to someone who knows what they are doing... drop another 100.00 on it.. and then he'd have one of the best scopes ever made. Or alternatively... and better... just start in on the PM3218...itself a very fine instrument, with a double insulated power supply... and way overkill, for a beginner. Look, I'm not unsympathetic... it's just that...too often.. after parting with some scarce cash... or finding some Tek picked apart in a basement somewhere, where its been languishing for a generation...I've witnessed the havoc wreaked by someone trying to "fix" them. If you want to call me a dumb ass... for thinking this way... well fine... just PM me to do it. I can't promise I'll reply to that... but, I'll read your message. Best regards and wishes. Roy --- This email has been checked for viruses by AVG. -- Dennis Tillman W7pF TekScopes Moderator -- Dennis Tillman W7pF TekScopes Moderator |
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Re: Encouraging beginners: What are we accomplishing?
Double Yikes!
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Hello Dennis, thanks for the huge reply, I feel bad that you have spent many hours on it. I have received your message loud and clear. Good to know that you and Chuck are still mates, he did explain that in another post. Dennis, please continue to run the group. I did not intend to undermine you. I was just mentioning something that annoyed me. The abrupt end of Chuck's explaination of how to measure Xc using a scope. Just when his electronics lesson was getting interesting the whole discussion was stopped. OK, I accept your reasons. You said, "TekScopes is about classic Tektronix test equipment, its use, repair, and collecting". I believe in that too. About 15 or 16 years ago, on this group, I asked some dumb questions about the air filter or lack of one, on my newly aquired 454 oscilloscope. Someone in the USA offered to send me some filter material. How Generous! A Mr. Denis Cobly, an ex Tektronix employee piped up on this group and said he was in Sydney also and I should call into "Trio Smartcal" and pick up filter material rather than let a Tekscope group member in USA send it to me. I found out that "Smartcal" was a little company set up by ex Tektronix workers when Tektronix folded in Sydney. Some time later the name changed to Trio Smartcal. I got to know Mr Denis Cobly by asking dumb questions and buying junked items. Out of the blue one day he offered me a temporay job. I was in heaven, surrounded by Tektronix people and Tektronix equipment. Mr Denis Cobly explained that I was to look after "the junk" leaving his experienced boys to the more complex items that came in for repair and calibration. One day a 475 scope landed on my bench. It came in a specially built Aluminium container with Qantas Airline calibration labels on it. It was in mint condition, no signs of use. I was given a check list to test the scopes performance but no adjustments to be made. It was explained that this scope was priceless as the aircraft makers specified this particular model 475 had to be used. Like I said before, I was in heaven. The ex Tektronix engineers around me were so helpfull in teaching me how to use the TM500 series instruments used to check this 475 scope. Dennis, repair of old test equipment and learning along the way is what I like to do. Bruce is struggling to repair his 475 scope on the "475 questions thread" Ex Tektronix people helped me with a 475 scope years ago. I support Bruce in fixing his 475 scope even though the thread is long and boring to some people on the group. I hope I have explained where I am coming from. Regards, John Crighton Sydney ----- Original Message -----
From: "Dennis Tillman W7pF" <dennis@...> To: <[email protected]> Sent: Thursday, May 28, 2020 10:54 AM Subject: Re: [TekScopes] Encouraging beginners: What are we accomplishing? YIKES! Hi John, I would like to make amends for anything I said to Chuck. I have known him as a contributor to TekScopes for the past 17 years. I consider myself fortunate that he has shared his experience and observations as a member of other groups with me. We communicate with each other regularly off list. He was planning to stop for a visit until the virus put everything on hold. Only Chuck can say if your characterization is correct. Chuck is not shy so if he has something to say I know he will :) If possible put yourself in my shoes for a minute. Two weeks ago on TekScopes several important issues were conflated and I was suddenly feeling a lot of stress while I tried to sort out how best to proceed. The ESR Meter thread resurfaced once again and I requested that the participants consider the impact on our other members if they continued. I find it ironic that you just clearly expressed your preference that the recent 475 thread be allowed to continue ad infinitum by taking issue with Roy Thistle. You singled out the one individual who, like you with the 475 thread, was a participant in the lengthy ESR thread until Roy took charge of the issue by creating a new ESR Forum on 开云体育. That relieved some of the pressure I was feeling from members. Once again, Thank You Roy! Some members saw ESR Meters as a legitimate Tek related topic since they are a troubleshooting tool. Other members thought this topic was not specific enough to TekScopes and requested I stop it. My responsibility is to choose between them. Fortunately I didn't have to because Roy Thistle took charge and created an ESR Forum on 开云体育. Chuck and I have both been around long enough to remember teletypes. So it was not really an issue when I saw the "character sketch" he included in an email describing own to make an engineer's ESR Meter. I watched as one member after another asked what that pile of hieroglyphics was supposed to be. A few people understood it and provided an explanation. The explanations resulted in still more questions/confusion which required even longer explanations. Chuck and I both find it strange that something so simple could cause so much confusion. I realized everyone needed instructions on how to decipher it. So I provided the instructions to understand what Chuck had drawn. The issue of allowing attachments generated a lot of polarized responses pro and con. Some of the responses were verging on rude which surprised me. I have no experience with attachments and out of personal ignorance I thought about all the things that could go wrong. I needed to learn more about attachments ASAP and I started to do just that. I think Chuck must have sensed I was confused and having a hard time with this because he contacted me and made many good suggestions about where I should go and who I could discuss my concerns with to learn more. Attachments have benefits and they have drawbacks. I have seen some of the benefits. I am still waiting for answers about how to eliminate or minimize the drawbacks. I spent many hours today writing this reply to you (this is the third time I wrote it, starting over from the beginning each time) because a brand new issue appeared yesterday which has all the makings of a controversy that is going to be a whopper. A few days ago I couldn't help but notice the "475 Questions" thread was getting very long. It is currently at 148 posts. I took a look at a few of the posts and I was stunned to see a member ask what "exp" meant. I couldn't spend much time thinking about it because yesterday a member got right to the core of that issue when he posted this new topic "Encouraging beginners: What are we accomplishing?" Apparently his question is not easy to answer to everyone's satisfaction. One more thing before I'll permit you to step out of my shoes: All of these issues have generated a lot of comments that are taking a huge amount of my time to respond to. That is less time I have to get the answers to the whether to enable attachments I have asked of other group moderator/owners. That was the hot issue 2 weeks ago. That is how far behind I am. I will probably choose to ignore this new topic until I reach a conclusion on the previous hot topic. Out of necessity I may stop responding entirely until I catch up. If you, John, would like to take my place in the interim please feel free. A few things to remember if you do: TEKSCOPES GOAL (from Michael Dunn in 2000): "TekScopes is about classic Tektronix test equipment, its use, repair, and collecting". THE GOLDEN RULE FOR GROUPS (from Stefan Trethan in 2018): “No politics, no religion, no sports, simple as that.” THE MODERATORS JOB IS TO STOP THIS PATTERN BEFORE IT REACHES #5 1. A slightly OT post is made. 2. It generates an unusually large number of responses. 3. This generates even more comments that go off at tangents. 4. Someone asks that the participants bring it under control. 5. That request creates more posts in support of the original slightly O.T. post. 6. Someone replies with "if you don't like it use your delete key" 7. That results in comments pro and con about whether the original post was O.T. 8. The posts die down over the next week. 9. If they don't die down the moderator will ask that the topic be put to bed. TEKSCOPES IS NOT A SALES SITE: EBay, Craigslist, etc. are the proper place to list items you have for sale. However if you are offering our members scarce parts, sub-assemblies, instruments, etc. at prices that our members can afford then it makes perfect sense to offer them on TekScopes. Dennis Tillman W7pF -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of John Crighton Sent: Tuesday, May 26, 2020 10:04 PM To: [email protected] Subject: Re: [TekScopes] Encouraging beginners: What are we accomplishing? Hello Roy, I am really surprised at you of all people sounding like a wet blanket. The owner of this tekscope group told you in no uncertain terms if you want to talk about ESR Meters to go and form your own group. Which to your credit you did just that. I also did not like the way that the owner of this group, Dennis Tillman, jumped on Mr Chuck Harris for describing how to use an oscilloscope with a function generator to check capacitors for value and ESR. Shutting someone up for describing how to use an oscilloscope on an oscilloscope group is to me just plain crazy. Those are rules that you have to obey, like them or not. Roy, if you are not enjoying reading about the repair of the 475 scope by a beginner then do not read the thread. It is that simple! I think it is marvellous that so many people on this group are willing to help an individul fix his 475 scope. What a great thing to do, while we are in corona virus lock down. My fellow countryman Graham VK1GVC, down in Canberra is doing a great job helping Bruce and so so are all the othere people. The side benefit for me and no doubt others on this group is that Bruce is asking basic questions as a beginner that other people on this group might not dare to ask for fear of looking foolish. Keep asking questions Bruce. I want you to fix this scope. Regards, John Crighton Sydney ----- Original Message ----- From: "Roy Thistle" <roy.thistle@...> To: <[email protected]> Sent: Wednesday, May 27, 2020 1:51 PM Subject: [TekScopes] Encouraging beginners: What are we accomplishing? Hi all TekScopers: Reading through a long thread, recently posted, caused me to wonder.. just what are TekScopers accomplishing with threads like this... and why are we encouraging someone who is "... new to electronics..." to dig into a 475?... one of the most complex, and compact, analog instruments ever designed. I suppose.. in consideration... Michael discouraged the use of a Mr. Carlson super Weller-kluge special, on the 475's pcb(s)... but, ya know... somewhere the thread... the 475 owner hints he paid 20.00 for 475?, and he's also got a nonworking? PM3218 too. So why didn't someone just recommend/... right off the bat... to take the 475 to someone who knows what they are doing... drop another 100.00 on it... and then he'd have one of the best scopes ever made. Or alternatively... and better... just start in on the PM3218...itself a very fine instrument, with a double insulated power supply... and way overkill, for a beginner. Look, I'm not unsympathetic... it's just that...too often.. after parting with some scarce cash... or finding some Tek picked apart in a basement somewhere, where its been languishing for a generation...I've witnessed the havoc wreaked by someone trying to "fix" them. If you want to call me a dumb ass... for thinking this way... well fine... just PM me to do it. I can't promise I'll reply to that... but, I'll read your message. Best regards and wishes. Roy --- This email has been checked for viruses by AVG. -- Dennis Tillman W7pF TekScopes Moderator |
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Re: 475 questions
According to this chart: , that's a >Red=2, Violet=7, Grey=.01 multiplier, Green = 16V.Bruce, The chart that many people find in a Google search does not cover three band caps correctly. Refer to the TEKTRONIX manual to find the CORRECT method to decode the Tektronix marking system. Their system varies from the so called “standard” system. This leads to errors and misunderstandings. This cap can be read correctly as below, colors indicate this: Red = 2 Violet =7 Green= 5. Multiplier in picofarads Therefore, this is 27followed by 5 zeros. This indicates the capacitance in pico faraday 2700000 pF =2.7uF. So using this method, this one appears correct and agrees with the parts listing. The TEKTRONIX marking method for these caps always designates voltage and tolerance using vertical paint daubs or stripes on the side of the cap body. Capacitance is always designated with the horizontal bands. AGAIN, refer to the TEK manual for a detailed explanation of their marking methods. I found that Tek typically places the vertical paint daubs on the positive side of the capacitor. Many Tantalum caps do not have a voltage designator band. This one is supposed to be 50V, according to the parts list. That Voltage Value can usually be derived indirectly from the known operating voltage of the circuit. In this case, common sense tells us this cannot be a 16V cap, since it is operating in a circuit using a higher voltage than 16V. You would want to replace this with one of at least the same or greater voltage rating. -- Michael Lynch Dardanelle, AR |
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Re: Encouraging beginners: What are we accomplishing?
Chuck Harris
Hi Dennis,
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We're good. In a fit of pique, I mentioned leaving, because I wasn't here to be scolded. It wasn't that you scolded me, but rather you scolded a topic I was involved with. And to call you a scold is pretty hyperbolic. I'm an engineer, I could argue for weeks about why I was right and you were wrong... and I could argue for weeks about why I was wrong and you were right. It really doesn't matter. Like most here, I am rather tired of being dictated to about my health habits, and whether or not I am the the reincarnation of Typhoid Mary. Peace to all, and let's keep buggering on! -Chuck Harris Dennis Tillman W7pF wrote: YIKES! |
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Re: Encouraging beginners: What are we accomplishing?
My experience with Tektronix began far before I had a Tek scope. I was
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about 11 years old and saw advertisements in Scientific American for Tektronix oscilloscopes. I wanted a catalog to learn more about them. I wrote a letter to Tektronix (I believe it was to the HQ in Beaverton) asking for a catalog. Whoever received it must have figured out I was a kid - no company name or address and clearly a home address. I think my English was reasonable. A few weeks later, a catalog showed up in the mail. I never forgot how well they treated me. They could have disregarded that letter, but they were nice enough to fulfill my request. As a result, when I had the chance to recommend a replacement scope for a lab I was working in (I was the only one with any electronics experience at all and it was mostly self-taught) I asked them what they wanted to use it for. I don't recall the model I suggested but I remember they wanted a high-gain differential amplifier. I believe it must have been a 560-series with a 2A61 vertical amplifier. This was long before the 7000-series and the 7A22. They were looking at low voltage, low-frequency bioelectric signals. They had preamplifiers if they needed them and Faraday chambers for single neuron work. So, Tektronix got a purchase order based on my memory of how well they treated me. It was a few years later that I acquired the 500-series scopes (DoD surplus) that we used in the lab. I will say that Hewlett-Packard also sent me a catalog, but by this time, I was a college student. I was most interested in their frequency counters and time/frequency stuff. I eventually acquired (surplus again) the famous 5245L and later a 5248M. Both still work. Also a 107BR quartz standard which also still works. More recently, a 105A quartz standard. I ran this thing against WWVB with a Fluke VLF receiver and the 105A achieves 1 part in 1E11. The frequency and time stuff is for fun. The Tek connection? Checking the sweep frequency against the standard output. The Tektronix parts folks were also very kind. I even had an account with them, and though they offered to let me buy parts on credit (at least up to a certain amount - I could not buy a replacement CRT on credit). It was great for manuals that were still in print, knobs, etc. I was lucky and the scopes I used and maintained did not need any custom parts. I did replace a couple of tubes in the 500s, though. I did pay the invoices quickly when i got them. I had directed others to Tektronix when they were looking for video test equipment. When we needed high-resolution, high performance (spot size uniformity across the CRT face, very low distortion) we bought Tektronix monitors for the lab (medical imaging). Tektronix being nice to a very young electronics enthusiast paid off for them. Steve H On Wed, May 27, 2020 at 10:06 AM Chuck Harris <cfharris@...> wrote:
Hi Roy, |
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