Locked
Re: Very OT: A response to Toby
On Fri, 23 Nov 2018 13:23:12 +0100, you wrote: Hello,
let me comment on this aspect:
I came to realize a few years ago that I am a modern day Noah. I have built an Ark to carry technology. But I have no children and most of the under 30 population considers books as door stops. This is the fault of today's university administration. I could tell stories, both from personal experience as student and from my exwifes consulting agency. In short, it makes good sense why I stopped my studies after achieving a BSc. Your average course textbook is roughly 150 USD or so. Making an Ebook out of them, the students are "only" charged 70 to 100 USD. Some order the dead tree copies, some don't. "look! we're saving them money!" Harvey
Tam
With best regards Tam Hanna ---
Enjoy electronics? Join 13700 other followers by visiting the Crazy Electronics Lab at
On 23. 11. 2018 3:48, Reginald Beardsley via Groups.Io wrote:
This will not be long, but I'll make a brief comment on my reasoning.
If you look back to the bronze age, that was only possible because there were high tenor (high metal content) ores close to the surface which could be readily mined. And there were abundant trees with which to make charcoal to smelt the ores. Neither of those still exist. The natural resources left whether minerals or fossil fuels are difficult to reach and in the case of metals, *very* low tenor. It takes tens of thousands of people to get a single drop of oil in 9000 ft of water at 30,000 ft BSL. I worked a little bit on St Malo, a Unocal discovery before Chevron bought them. I was riding home on the bus and chatting with a Brit who was subsea systems manager for Jack, a nearby Chevron discovery. All he was responsible for was the equipment that sits on the sea floor and ties in to the production system. He had a $2 billion dollar budget. This was in 2006 or 2007 Jack, St Malo and another field produced first oil in2014. They were discovered in 2003 and 2004. The FSPO (floating storage, production and offloading) system cost $7.5 billion dollars.
How many welders, machinists, fitters and other skilled tradesmen do you think it takes to spend that much money? This was 10 years of intense hard work by a vast number of people. My wild guess is that there were probably about 50-60,000 people involved at some point. Maybe only a few hours like me. All I did was do some synthetic seismograms for the well tie.
If the trucks stop delivering food for a week, there will never be food on the shelves again. Almost everyone has less than a week's supply of food. So it they can get it, they'll stock up as much as possible. In the context of a "just in time" inventory management environment there is *no* capacity for increasing the supply if demand increases. And if demand increases because of a shortage of truck drivers because most of them are sick or dead from influenza, or there has been a Carrington even, a high altitude nuke detonated above the US, a Crater Lake or Yellowstone level caldera collapse or any of a *very* long list of events I can recite., there will be even less capacity to supply food. My doctor, whom I've known since we were 10, tells me people can survive without food for about 60 days.
The net result i will be a period of 30-60 days of incredible violence during which 90% or more of the population will perish. The survivors will be scared and isolated. So social organization will be very difficult.
The Hollywood "Mad Max" version of this is ludicrous. Look at thew costumes. Clothing laced together with leather strips through metal eyelets? Where in the hell are they going to get eyelets? There are no refineries at well sites. There is very little oil left that is not 1000's of ft down. What is left is in places like remote parts of Mynamar.
There was a great article in the Oil and Gas Journal about 15-20 years ago about oil production in the interior. The wells are drilled by setting up a tripod with a pulley. A length of pipe with a beveled edge is attached to a rope. The length of pipe is raised and dropped until it fills with dirt. It is then hauled to the surface, the dirt removed and they start over. Periodically they drop plastic bags off water down the hole as they have found it increases the penetration rate. Once they reach the target, the oil is brought up using a bailer such as the well bucket a childhood friend used to draw water in the 60's.
From there it is transported by young women in 5 gallon jugs to the refinery which consists of a still made from 55 gallon drums.
The wells go dry pretty quickly, so they move over a few feet and rill another one. They even do this "offshore" in a lake using bamboo platforms.
They are very resourceful people, but they are not going to be making semiconductors or machine tools anytime soon unless someone provides a lot of assistance. But those are the only people who have *any* readily recoverable resources. They will survive a collapse of civilization far better than the rest of us. But they will also have no access to the knowledge that makes modern technology possible.
"Oh, but we can use scrap." Oh, yeah? And how many years before all the cars, trucks and other pieces of iron an steel are just brown spots on the ground? Far too low a tenor to be recoverable. A few metals such as gold don't oxidize, but most do. And all the metals important to technology do. Iron is extremely abundant and cast iron is just amazing. It's almost an argument for creationism it's so amenable to primitive methods. But if you don't have high tenor ore, you cannot dig up and smelt an ounce of it. Too much digging and too much tree cutting required.
I got interested in DIY technology around age 20. So at 65, I have spent 45 years trying to prepare for such things. But after reading all those books on the history of technology it sank in that there were two problems: social organization at a large scale (how may people did it take to build the pyramids) and resources which were accessible to technology such as used in Mynamar. Which is only slightly more refined than Drake used in 1859.
I have the tools to do *almost* everything and a library to tell you how. But I'm 65 and have glaucoma. So I'm in a race between dying and going blind. Both my parents lived into their 90's. I hope I do not. I can play guitar and harmonica rather well. Good enough that I can walk on stage and rip a tune with a band I've never played with. But I don't relish the idea of being "Blind Boy Rufus" (I was born with red hair and was given the nickname by my dad. I dropped when I graduated college with my BA in English lit).
I came to realize a few years ago that I am a modern day Noah. I have built an Ark to carry technology. But I have no children and most of the under 30 population considers books as door stops.
So, Toby, that's a short version of why I abandoned the project. It's a very gloomy future. And after 65 years of learning everything (except biological sciences) that I could I can offer no solution. The Silicon Valley elite imagine that when the collapse comes they and their family will get in their personal jet and fly away. Which is possible if they can fly the plane themselves. But the pilot is more likely to shoot the owner and family and take his family than take theirs and leave his own behind.
This is a wretched platform for writing. Doubtless there are many things in my writing which would make me cringe. I took a degree in literature because I wanted a good liberal arts education. The sole criticism I should make of it today is I should have taken math at least up to ordinary differential equations. I did do that later and a *lot* more.
Kids in high school don't learn algebra, geometry and trigonometry because their teachers don't know anything about applying it. But every good skilled tradesman uses them *every* day. And then are insulted because they didn't go to college. It's hard to be motivated to learn something which is difficult if you don't have a clue why you are doing it and neither does the teacher.
I'm going to end it here. Thank you Toby for asking. I hope that at least a few of you found it worthwhile reading.
Reg
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They were originally published by McGraw Hill (red cloth bindings) and later republished by Boston Technical Publishers (lesser-quality gray bindings). It took me quite awhile to collect all volumes. As I recall some titles were very difficult to find and finding any of them in better than “good” condition took a lot of patience.
The set was also republished in PDF form (I think by MIT or maybe IEEE), but as I recall the scans were not of high quality.
DaveD Sent from a small flat thingy
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On Nov 22, 2018, at 11:38, Mike Feher < n4fs@...> wrote: Hi Paul – ? There are 28 hardcover red books in the series, with one of them being an index. I am sure you can Google them to see the titles. Regards – Mike ? Mike B. Feher, N4FS 89 Arnold Blvd. Howell NJ 07731 848-245-9115 ? ? Hi interested in a set but the red lab books are new to me can you tell me the titles that make up the set ? Paul B ? -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Mike Feher Sent: 22 November 2018 16:09 To: [email protected] Subject: [HP-Agilent-Keysight-equipment] Rad Labs - ? I have a couple of complete sets of the RadLab books. They are available for sale if any one is interested. Thanks & have a great Thanksgiving - Mike ? Mike B. Feher, N4FS 89 Arnold Blvd. Howell NJ 07731 848-245-9115 ? -----Original Message----- From: [email protected] <[email protected]> On Behalf Of saipan59 Sent: Thursday, November 22, 2018 10:39 AM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] Rad Lab was NOT in Tuxedo Park! MIT ? [with a grin] ...And it pains me to see an educational thread corrupted by posting a New Topic, when you meant to post a Reply... ? I also have several of the original RadLab books. The one titled "Waveforms" is like a foundation text on pulse circuits and such. ? Pete ? ? ? ? ? ? ? ? ? ----- No virus found in this message. Checked by AVG - Version: 2016.0.8048 / Virus Database: 4793/15883 - Release Date: 08/14/18 Internal Virus Database is out of date. ?
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Wanted: side panels for HP 5071A Cesium standard.
I'm looking for a pair of side panels with carrying strap for an HP-vintage 5071A standard.
The part number appears to be 05071-00037.? I don't know if this part is unique to the 5071A or if other HP instruments of the same size used it as well.? I'll take anything that fits.
Per the specs, the instrument height is 133.4 mm (5.25 inches) and the depth is 498.5 mm (19.625 inches), excluding rear feet.? The panels are obviously a bit smaller than that.
Thanks!
John
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Locked
Re: Very OT: A response to Toby
I thought I had started a new topic. My apologies if I did not. I don't want the discussion here either. It grew out of the Rad Lab discussion. I will, to a degree, indulge people if some want to discuss the subject in a private email thread. However, it would be pretty limited. I'm engaged in a major project to develop FOSS DSO FW for Zynq based DSOs.
I am much more interested in the power detectors as I have a Millivac I'd like to revive even though my 438A w/ 8481D and 8482A is far superior. So far as I can tell, the only fault of the Millivac is a blown diode capsule, but at $400 for the capsule and $75 for a manual I'd have to find a cheaper repair.
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Michael A. Terrell
Michael A. Terrell
Michael A. TerrellI found a copy of Skolnik's RADAR Handbook at a flea market for $1, and one book dealer would hold any electronics related books back until I went through them.
Some Hamfests are a good place to find and sell electronics books, and test equipment. The 2018 Ocala Hamfest is December 1st, for those in Central Florida. I bought both books and test equipment there, last year.
<>
<,+Ocala,+FL+34470/@29.2108832,-82.132668,16.83z/data=!4m5!3m4!1s0x88e62b608a9ed4eb:0x2299d2a99c6b899a!8m2!3d29.2109973!4d-82.1305818>
Michael A. Terrell --
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-----Original Message----- From: Dave McGuire <mcguire@...> Sent: Nov 23, 2018 1:15 AM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] OT: Rad Lab thread.
On 11/22/18 7:39 PM, Brad Thompson wrote:
Last stop is your local secondhand shop. But based on what I've seen at Goodwill and Salvation Army stores, most of what gets donated are romance novels... (&) There's definitely a lot of garbage in the book section of most Goodwill stores. I mean, how many copies of the Twilight books did they really print? I think ALL of them are on the shelves of Goodwill stores; apparently even the "tweenagers" bore of them eventually
But in Goodwill stores in some geographic areas, there are some goodies to be found. Pittsburgh is an extremely high-tech city...there's a Goodwill store downtown in which my lady and I found a copy of Terman and a few nice books on the 8085 microprocessor this past summer. It's always worth a quick peek.
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Locked
Re: Very OT: A response to Toby
Guys, please!
This is still a hijacked thread regarding power detectors on a group about HP Instruments.
The world has (more than) enough on-line places for this sort of topic but I suggest this is *not* one of them.
Adrian
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On 11/23/2018 2:48 AM, Reginald Beardsley via Groups.Io wrote: This will not be long, but I'll make a brief comment on my reasoning.
If you look back to the bronze age, that was only possible because there were high tenor (high metal content) ores close to the surface which could be readily mined. And there were abundant trees with which to make charcoal to smelt the ores. Neither of those still exist. The natural resources left whether minerals or fossil fuels are difficult to reach and in the case of metals, *very* low tenor. It takes tens of thousands of people to get a single drop of oil in 9000 ft of water at 30,000 ft BSL. I worked a little bit on St Malo, a Unocal discovery before Chevron bought them. I was riding home on the bus and chatting with a Brit who was subsea systems manager for Jack, a nearby Chevron discovery. All he was responsible for was the equipment that sits on the sea floor and ties in to the production system. He had a $2 billion dollar budget. This was in 2006 or 2007 Jack, St Malo and another field produced first oil in2014. They were discovered in 2003 and 2004. The FSPO (floating storage, production and offloading) system cost $7.5 billion dollars.
How many welders, machinists, fitters and other skilled tradesmen do you think it takes to spend that much money? This was 10 years of intense hard work by a vast number of people. My wild guess is that there were probably about 50-60,000 people involved at some point. Maybe only a few hours like me. All I did was do some synthetic seismograms for the well tie.
If the trucks stop delivering food for a week, there will never be food on the shelves again. Almost everyone has less than a week's supply of food. So it they can get it, they'll stock up as much as possible. In the context of a "just in time" inventory management environment there is *no* capacity for increasing the supply if demand increases. And if demand increases because of a shortage of truck drivers because most of them are sick or dead from influenza, or there has been a Carrington even, a high altitude nuke detonated above the US, a Crater Lake or Yellowstone level caldera collapse or any of a *very* long list of events I can recite., there will be even less capacity to supply food. My doctor, whom I've known since we were 10, tells me people can survive without food for about 60 days.
The net result i will be a period of 30-60 days of incredible violence during which 90% or more of the population will perish. The survivors will be scared and isolated. So social organization will be very difficult.
The Hollywood "Mad Max" version of this is ludicrous. Look at thew costumes. Clothing laced together with leather strips through metal eyelets? Where in the hell are they going to get eyelets? There are no refineries at well sites. There is very little oil left that is not 1000's of ft down. What is left is in places like remote parts of Mynamar.
There was a great article in the Oil and Gas Journal about 15-20 years ago about oil production in the interior. The wells are drilled by setting up a tripod with a pulley. A length of pipe with a beveled edge is attached to a rope. The length of pipe is raised and dropped until it fills with dirt. It is then hauled to the surface, the dirt removed and they start over. Periodically they drop plastic bags off water down the hole as they have found it increases the penetration rate. Once they reach the target, the oil is brought up using a bailer such as the well bucket a childhood friend used to draw water in the 60's.
From there it is transported by young women in 5 gallon jugs to the refinery which consists of a still made from 55 gallon drums.
The wells go dry pretty quickly, so they move over a few feet and rill another one. They even do this "offshore" in a lake using bamboo platforms.
They are very resourceful people, but they are not going to be making semiconductors or machine tools anytime soon unless someone provides a lot of assistance. But those are the only people who have *any* readily recoverable resources. They will survive a collapse of civilization far better than the rest of us. But they will also have no access to the knowledge that makes modern technology possible.
"Oh, but we can use scrap." Oh, yeah? And how many years before all the cars, trucks and other pieces of iron an steel are just brown spots on the ground? Far too low a tenor to be recoverable. A few metals such as gold don't oxidize, but most do. And all the metals important to technology do. Iron is extremely abundant and cast iron is just amazing. It's almost an argument for creationism it's so amenable to primitive methods. But if you don't have high tenor ore, you cannot dig up and smelt an ounce of it. Too much digging and too much tree cutting required.
I got interested in DIY technology around age 20. So at 65, I have spent 45 years trying to prepare for such things. But after reading all those books on the history of technology it sank in that there were two problems: social organization at a large scale (how may people did it take to build the pyramids) and resources which were accessible to technology such as used in Mynamar. Which is only slightly more refined than Drake used in 1859.
I have the tools to do *almost* everything and a library to tell you how. But I'm 65 and have glaucoma. So I'm in a race between dying and going blind. Both my parents lived into their 90's. I hope I do not. I can play guitar and harmonica rather well. Good enough that I can walk on stage and rip a tune with a band I've never played with. But I don't relish the idea of being "Blind Boy Rufus" (I was born with red hair and was given the nickname by my dad. I dropped when I graduated college with my BA in English lit).
I came to realize a few years ago that I am a modern day Noah. I have built an Ark to carry technology. But I have no children and most of the under 30 population considers books as door stops.
So, Toby, that's a short version of why I abandoned the project. It's a very gloomy future. And after 65 years of learning everything (except biological sciences) that I could I can offer no solution. The Silicon Valley elite imagine that when the collapse comes they and their family will get in their personal jet and fly away. Which is possible if they can fly the plane themselves. But the pilot is more likely to shoot the owner and family and take his family than take theirs and leave his own behind.
This is a wretched platform for writing. Doubtless there are many things in my writing which would make me cringe. I took a degree in literature because I wanted a good liberal arts education. The sole criticism I should make of it today is I should have taken math at least up to ordinary differential equations. I did do that later and a *lot* more.
Kids in high school don't learn algebra, geometry and trigonometry because their teachers don't know anything about applying it. But every good skilled tradesman uses them *every* day. And then are insulted because they didn't go to college. It's hard to be motivated to learn something which is difficult if you don't have a clue why you are doing it and neither does the teacher.
I'm going to end it here. Thank you Toby for asking. I hope that at least a few of you found it worthwhile reading.
Reg
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Locked
Re: Very OT: A response to Toby
Hello, let me comment on this aspect: I came to realize a few years ago that I am a modern day Noah. I have built an Ark to carry technology. But I have no children and most of the under 30 population considers books as door stops. This is the fault of today's university administration. I could tell stories, both from personal experience as student and from my exwifes consulting agency. In short, it makes good sense why I stopped my studies after achieving a BSc. Tam With best regards Tam Hanna --- Enjoy electronics? Join 13700 other followers by visiting the Crazy Electronics Lab at On 23. 11. 2018 3:48, Reginald Beardsley via Groups.Io wrote: This will not be long, but I'll make a brief comment on my reasoning.
If you look back to the bronze age, that was only possible because there were high tenor (high metal content) ores close to the surface which could be readily mined. And there were abundant trees with which to make charcoal to smelt the ores. Neither of those still exist. The natural resources left whether minerals or fossil fuels are difficult to reach and in the case of metals, *very* low tenor. It takes tens of thousands of people to get a single drop of oil in 9000 ft of water at 30,000 ft BSL. I worked a little bit on St Malo, a Unocal discovery before Chevron bought them. I was riding home on the bus and chatting with a Brit who was subsea systems manager for Jack, a nearby Chevron discovery. All he was responsible for was the equipment that sits on the sea floor and ties in to the production system. He had a $2 billion dollar budget. This was in 2006 or 2007 Jack, St Malo and another field produced first oil in2014. They were discovered in 2003 and 2004. The FSPO (floating storage, production and offloading) system cost $7.5 billion dollars.
How many welders, machinists, fitters and other skilled tradesmen do you think it takes to spend that much money? This was 10 years of intense hard work by a vast number of people. My wild guess is that there were probably about 50-60,000 people involved at some point. Maybe only a few hours like me. All I did was do some synthetic seismograms for the well tie.
If the trucks stop delivering food for a week, there will never be food on the shelves again. Almost everyone has less than a week's supply of food. So it they can get it, they'll stock up as much as possible. In the context of a "just in time" inventory management environment there is *no* capacity for increasing the supply if demand increases. And if demand increases because of a shortage of truck drivers because most of them are sick or dead from influenza, or there has been a Carrington even, a high altitude nuke detonated above the US, a Crater Lake or Yellowstone level caldera collapse or any of a *very* long list of events I can recite., there will be even less capacity to supply food. My doctor, whom I've known since we were 10, tells me people can survive without food for about 60 days.
The net result i will be a period of 30-60 days of incredible violence during which 90% or more of the population will perish. The survivors will be scared and isolated. So social organization will be very difficult.
The Hollywood "Mad Max" version of this is ludicrous. Look at thew costumes. Clothing laced together with leather strips through metal eyelets? Where in the hell are they going to get eyelets? There are no refineries at well sites. There is very little oil left that is not 1000's of ft down. What is left is in places like remote parts of Mynamar.
There was a great article in the Oil and Gas Journal about 15-20 years ago about oil production in the interior. The wells are drilled by setting up a tripod with a pulley. A length of pipe with a beveled edge is attached to a rope. The length of pipe is raised and dropped until it fills with dirt. It is then hauled to the surface, the dirt removed and they start over. Periodically they drop plastic bags off water down the hole as they have found it increases the penetration rate. Once they reach the target, the oil is brought up using a bailer such as the well bucket a childhood friend used to draw water in the 60's.
From there it is transported by young women in 5 gallon jugs to the refinery which consists of a still made from 55 gallon drums.
The wells go dry pretty quickly, so they move over a few feet and rill another one. They even do this "offshore" in a lake using bamboo platforms.
They are very resourceful people, but they are not going to be making semiconductors or machine tools anytime soon unless someone provides a lot of assistance. But those are the only people who have *any* readily recoverable resources. They will survive a collapse of civilization far better than the rest of us. But they will also have no access to the knowledge that makes modern technology possible.
"Oh, but we can use scrap." Oh, yeah? And how many years before all the cars, trucks and other pieces of iron an steel are just brown spots on the ground? Far too low a tenor to be recoverable. A few metals such as gold don't oxidize, but most do. And all the metals important to technology do. Iron is extremely abundant and cast iron is just amazing. It's almost an argument for creationism it's so amenable to primitive methods. But if you don't have high tenor ore, you cannot dig up and smelt an ounce of it. Too much digging and too much tree cutting required.
I got interested in DIY technology around age 20. So at 65, I have spent 45 years trying to prepare for such things. But after reading all those books on the history of technology it sank in that there were two problems: social organization at a large scale (how may people did it take to build the pyramids) and resources which were accessible to technology such as used in Mynamar. Which is only slightly more refined than Drake used in 1859.
I have the tools to do *almost* everything and a library to tell you how. But I'm 65 and have glaucoma. So I'm in a race between dying and going blind. Both my parents lived into their 90's. I hope I do not. I can play guitar and harmonica rather well. Good enough that I can walk on stage and rip a tune with a band I've never played with. But I don't relish the idea of being "Blind Boy Rufus" (I was born with red hair and was given the nickname by my dad. I dropped when I graduated college with my BA in English lit).
I came to realize a few years ago that I am a modern day Noah. I have built an Ark to carry technology. But I have no children and most of the under 30 population considers books as door stops.
So, Toby, that's a short version of why I abandoned the project. It's a very gloomy future. And after 65 years of learning everything (except biological sciences) that I could I can offer no solution. The Silicon Valley elite imagine that when the collapse comes they and their family will get in their personal jet and fly away. Which is possible if they can fly the plane themselves. But the pilot is more likely to shoot the owner and family and take his family than take theirs and leave his own behind.
This is a wretched platform for writing. Doubtless there are many things in my writing which would make me cringe. I took a degree in literature because I wanted a good liberal arts education. The sole criticism I should make of it today is I should have taken math at least up to ordinary differential equations. I did do that later and a *lot* more.
Kids in high school don't learn algebra, geometry and trigonometry because their teachers don't know anything about applying it. But every good skilled tradesman uses them *every* day. And then are insulted because they didn't go to college. It's hard to be motivated to learn something which is difficult if you don't have a clue why you are doing it and neither does the teacher.
I'm going to end it here. Thank you Toby for asking. I hope that at least a few of you found it worthwhile reading.
Reg
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Mike- Can’t help with the big picture but I’m after a 1932 first edition of Terman-should you have one you want to relinquish…Not found anything earlier than the 1937 ?edition since I started to look a few years back. DaveB, NZ ? ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Mike Feher Sent: Friday, November 23, 2018 10:04 To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] OT: Rad Lab thread.? Hi Guys – ? My question is what do I do with all my engineering college texts both undergrad and grad type. They are mainly from the ‘60s and I believe relatively worthless now. I cannot stand to throw them away. Ideas appreciated. – Mike ? Mike B. Feher, N4FS 89 Arnold Blvd. Howell NJ 07731 848-245-9115 ? From: [email protected] <[email protected]> On Behalf Of Jeff Kruth via Groups.Io Sent: Thursday, November 22, 2018 3:38 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] OT: Rad Lab thread. ? Boy, where to start. By training I am a microwave engineer, ran an R&D company doing DoD and three letter work for 30 years, then was instrumental in creating the Space Science program here at Morehead State U, one of five in the country. I teach in both the undergrad & master programs. So what! But since you told me who you are, now I tell you. My library and yours are same sized. Mine is nearly all science & tech, mostly electronic. I have purchased large lots of books from the libraries of companies that have gone belly up. In a message dated 11/22/2018 1:42:19 PM Eastern Standard Time, pulaskite@... writes:
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Réf. : Re: Réf. : Re: 50 ohm thermocouples was RE: [HP-Agilent-Keysight-equipment] 478A power sensor recal for HP meters (was diode mounts)
where .. where !
as usual
in the box with some transistors
under another box containning some screws
behind the big parcel on the floor !
?
same problem here !
hi ...
?
?
?
?
?
-------Message original-------
?
Date : 23/11/2018 10:25:49
Sujet : Re: Réf. : Re: 50 ohm thermocouples was RE: [HP-Agilent-Keysight-equipment] 478A power sensor recal for HP meters (was diode mounts)
?
Merci Chef! I must have some original HP spare thermistors...... But where......
Best 73 de
Harke
On Friday, November 23, 2018, 12:58:27 AM GMT+1, f1chf <F1CHF@...> wrote:
may be this news can help
F1CHF
?
?
?
?
?
-------Message original-------
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Date : 22/11/2018 17:34:46
Sujet : Re: 50 ohm thermocouples was RE: [HP-Agilent-Keysight-equipment] 478A power sensor recal for HP meters (was diode mounts)
?
Thanks Jeff! Nice read.
Best 73 de
Harke
On Thursday, November 22, 2018, 5:30:52 PM GMT+1, Jeff Kruth via Groups.Io <kmec@...> wrote:
The screws are weird!? Back in the late '70's when a 478A head was worth $250 working (real money then!), I used to repair these. I ran a lab at Westinghouse Defense in Baltimore that did MIC work, microwave micro-assembly and wire & ribbon bonding. I used to pay the technicians on their lunch hours to mount salvaged thermistor beads for me. If you blow out a 478A with too much RF, the reference pair is still good. I used to salvage these and match them to the Ref pair in another head, replacing the blown RF pair.? Made a bit of cash that way!
The screws do NOT contact anything, instead they "approach" the thermistor beads, being aligned directly above them. My take on it is that they change the ambient temperature environment by adding a small bit of "hotter" metal closer to the bead, sort of like the DC offset adjustment on an op-amp. However, I could be wrong: instead of adding heat, they may change the reactance of the bead to the chopper frequency, but this seems less likely, as the size is so small (not much capacitance and the frequency of the chopper is low (IIRC, about 10 KHz).
The general failure in adjustment in an attempt to re-calibrate the head is to insert the screw a little too far so that it hits the bead and snaps a wire lead off it.
Hi Paul!? I found that the "driftiness" of the head can sometimes be improved by working the re-balance adjusting the screw pair alternatively, back and forth. 1/8 turn out on one, 1/8 turn in on the other, etc.? YMMV.
I used to leave the head shell off and hold the mount in my hand to heat it, release and watch the behavior of the re-compensated mount as it settles back to ambient. I could get them pretty good after a while.?
Oh well, all that was a really long time ago now, it seems, in a period when I had more time than money, now the other is true. Found a box the other day of a pile of 478 & 8478 guts, left over bits from these days, some beads missing. Off to gold scrap, I guess!
73
J. Kruth
Hi Jeff??
good to talk to you again regarding the 478 and rebalancing the head using the screws
I have found that the temperature? compensation isn’t as good after you have to rebalance using the screws
?
By the way never opened the 478? to find out how the screws work
Paul B
In a message dated 11/22/2018 11:01:39 AM Eastern Standard Time, yrrah53@... writes:
Interesting point. I have not worked with thermistor heads since ages but I always wondered how the screws work on the HP478 and HP8478?
73 de
Harke
On Thursday, November 22, 2018, 4:58:38 PM GMT+1, Paul Bicknell <paul@...> wrote:
Hi Jeff??
good to talk to you again regarding the 478 and rebalancing the head using the screws
I have found that the temperature? compensation isn’t as good after you have to rebalance using the screws
?
By the way never opened the 478? to find out how the screws work
Paul B
?
| |
toggle quoted message
Show quoted text
From: [email protected] [mailto: [email protected] ] On Behalf Of Jeff Kruth via Groups.Io Sent: 22 November 2018 15:38 To: [email protected] Subject: Re: 50 ohm thermocouples was RE: [HP-Agilent-Keysight-equipment] Issue with homemade diode power sensor for HP meters
?
Really? Because HP used the same idea in the 478A & 8478A heads, they were 200 ohms series under AC bias, 50 ohms to RF, but when measured "cold" with an ohm-meter they were approx 3-4K ohms. I would have thought G-M would have used a similar method.
The big thing with the HP heads was the balance between the ref thermistor pair and the measurement thermistor pair. If the measurement pair was damaged by excess RF power, the "rest" resistance was too different from the temperature reference pair (say 7K instead of 4 K). SO you could no longer balance them with the screws.
In a message dated 11/22/2018 9:29:03 AM Eastern Standard Time, paul@... writes:
Regarding the TFT ?Marconi? power meter ?they had 2? thermisters? at 100 ohm each
?And connected so that DC they added up to 200 ohm but presented a 50? to an AC signal
?
The power sensor was easily tested as the 2 large pins on the convector should read 200 ohm
?
?
I have such an animal here a GM 460B with that TFT hermocouple. It is an ancient beast. They got bought up by Marconi down the line.
https://patents.google.com/patent/US3384819
No virus found in this message. Checked by AVG - www.avg.com Version: 2016.0.8048 / Virus Database: 4793/15883 - Release Date: 08/14/18 Internal Virus Database is out of date.
No virus found in this message. Checked by AVG - www.avg.com Version: 2016.0.8048 / Virus Database: 4793/15883 - Release Date: 08/14/18 Internal Virus Database is out of date.
?
?
|
(&) "Oh, Harold!" she breathed, as he frantically fumbled with the restraining fasteners
on her GPIB harness connectors....? [From "Fifty Shades of Gray Pixels"]
?
Now... what a novel that would be...!!
?
Just imagine, the steamy smoky environment as his attenuator coupling vaporised from mis-application of a huge power surge.
?
I sense a whole series of novels approaching.
Moving swiftly on.
?
Nigel
?
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-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Brad Thompson
Sent: 23 November 2018 00:39
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] OT: Rad Lab thread.
?
On 11/22/2018 4:03 PM, Mike Feher wrote:
> Hi Guys –
>
> My question is what do I do with all my engineering college texts both
> undergrad and grad type. They are mainly from the ‘60s and I believe
> relatively worthless now. I cannot stand to throw them away. Ideas
> appreciated. – Mike
>
>?
Hello, Mike--
?
I volunteer at a local book sale as the sorter/pricer for science and
technology
books. We typically reject almost all texts, especially older editions
and those which have been stricken by the Mad Highlighter (*). Recent
editions may
get shipped to a used-book wholesaler. Professors may specify that their
students use the prof's own text, for which he or she may receive
royalties from the publisher-- hence, older editions are no longer
welcome and the poor students are out $100 per text or more.
?
For our book sale, I'm free to accept books that I deem saleable or of
classic interest (e.g., Terman, Rad Lab, ARRL Handbooks) and I price
them inexpensively.
?
The next possible outlet is your local public library, which may have a
free-to-take cart.
Some libraries charge a small amount for discarded or donated books and
may accept your gift books. Local libraries may welcome donations of books
that are in good condition for their fundraising sales.
?
Last stop is your local secondhand shop. But based on what I've seen at
Goodwill and Salvation Army stores, most of what gets donated are
romance novels... (&)
?
73--
?
Brad? AA1IP
?
(*) The Mad Highlighter typically approaches a textbook with yellow
marker in hand and
and begins highlighting every other sentence (regardless of content) on
page one.
?
Twenty or so pages into the book, the highlighting thins out, and thirty
pages in stops altogether.. At that point, it's safe to assume that the
luckless book owner has dropped
the course....
?
(&) "Oh, Harold!" she breathed, as he frantically fumbled with the
restraining fasteners
on her GPIB harness connectors....? [From "Fifty Shades of Gray Pixels"]
?
?
|
Re: Réf. : Re: 50 ohm thermocouples was RE: [HP-Agilent-Keysight-equipment] 478A power sensor recal for HP meters (was diode mounts)
Merci Chef! I must have some original HP spare thermistors...... But where...... Best 73 de
Harke
On Friday, November 23, 2018, 12:58:27 AM GMT+1, f1chf <F1CHF@...> wrote:
may be this news can help
F1CHF
?
?
?
?
?
-------Message original-------
?
Date : 22/11/2018 17:34:46
Sujet : Re: 50 ohm thermocouples was RE: [HP-Agilent-Keysight-equipment] 478A power sensor recal for HP meters (was diode mounts)
?
Thanks Jeff! Nice read.
Best 73 de
Harke
On Thursday, November 22, 2018, 5:30:52 PM GMT+1, Jeff Kruth via Groups.Io <kmec@...> wrote:
The screws are weird!? Back in the late '70's when a 478A head was worth $250 working (real money then!), I used to repair these. I ran a lab at Westinghouse Defense in Baltimore that did MIC work, microwave micro-assembly and wire & ribbon bonding. I used to pay the technicians on their lunch hours to mount salvaged thermistor beads for me. If you blow out a 478A with too much RF, the reference pair is still good. I used to salvage these and match them to the Ref pair in another head, replacing the blown RF pair.? Made a bit of cash that way!
The screws do NOT contact anything, instead they "approach" the thermistor beads, being aligned directly above them. My take on it is that they change the ambient temperature environment by adding a small bit of "hotter" metal closer to the bead, sort of like the DC offset adjustment on an op-amp. However, I could be wrong: instead of adding heat, they may change the reactance of the bead to the chopper frequency, but this seems less likely, as the size is so small (not much capacitance and the frequency of the chopper is low (IIRC, about 10 KHz).
The general failure in adjustment in an attempt to re-calibrate the head is to insert the screw a little too far so that it hits the bead and snaps a wire lead off it.
Hi Paul!? I found that the "driftiness" of the head can sometimes be improved by working the re-balance adjusting the screw pair alternatively, back and forth. 1/8 turn out on one, 1/8 turn in on the other, etc.? YMMV.
I used to leave the head shell off and hold the mount in my hand to heat it, release and watch the behavior of the re-compensated mount as it settles back to ambient. I could get them pretty good after a while.?
Oh well, all that was a really long time ago now, it seems, in a period when I had more time than money, now the other is true. Found a box the other day of a pile of 478 & 8478 guts, left over bits from these days, some beads missing. Off to gold scrap, I guess!
73
J. Kruth
Hi Jeff??
good to talk to you again regarding the 478 and rebalancing the head using the screws
I have found that the temperature? compensation isn’t as good after you have to rebalance using the screws
?
By the way never opened the 478? to find out how the screws work
Paul B
In a message dated 11/22/2018 11:01:39 AM Eastern Standard Time, yrrah53@... writes:
Interesting point. I have not worked with thermistor heads since ages but I always wondered how the screws work on the HP478 and HP8478?
73 de
Harke
On Thursday, November 22, 2018, 4:58:38 PM GMT+1, Paul Bicknell <paul@...> wrote:
Hi Jeff??
good to talk to you again regarding the 478 and rebalancing the head using the screws
I have found that the temperature? compensation isn’t as good after you have to rebalance using the screws
?
By the way never opened the 478? to find out how the screws work
Paul B
?
|
toggle quoted message
Show quoted text
From: [email protected] [mailto: [email protected] ] On Behalf Of Jeff Kruth via Groups.Io Sent: 22 November 2018 15:38 To: [email protected] Subject: Re: 50 ohm thermocouples was RE: [HP-Agilent-Keysight-equipment] Issue with homemade diode power sensor for HP meters
?
Really? Because HP used the same idea in the 478A & 8478A heads, they were 200 ohms series under AC bias, 50 ohms to RF, but when measured "cold" with an ohm-meter they were approx 3-4K ohms. I would have thought G-M would have used a similar method.
The big thing with the HP heads was the balance between the ref thermistor pair and the measurement thermistor pair. If the measurement pair was damaged by excess RF power, the "rest" resistance was too different from the temperature reference pair (say 7K instead of 4 K). SO you could no longer balance them with the screws.
In a message dated 11/22/2018 9:29:03 AM Eastern Standard Time, paul@... writes:
Regarding the TFT ?Marconi? power meter ?they had 2? thermisters? at 100 ohm each
?And connected so that DC they added up to 200 ohm but presented a 50? to an AC signal
?
The power sensor was easily tested as the 2 large pins on the convector should read 200 ohm
?
?
I have such an animal here a GM 460B with that TFT hermocouple. It is an ancient beast. They got bought up by Marconi down the line.
https://patents.google.com/patent/US3384819
No virus found in this message. Checked by AVG - www.avg.com Version: 2016.0.8048 / Virus Database: 4793/15883 - Release Date: 08/14/18 Internal Virus Database is out of date.
No virus found in this message. Checked by AVG - www.avg.com Version: 2016.0.8048 / Virus Database: 4793/15883 - Release Date: 08/14/18 Internal Virus Database is out of date.
?
|
On 11/23/2018 01:52 AM, Richard Knoppow wrote: Around here, meaning Los Angeles in general, used book stores are getting to be a rarity. Most used books are on the internet. I also buy a lot of books of the non-technical sort, at the bookstores in many public libraries. Mostly not technical books but there are a few. Typically, soft cover are 25c to 50c and hard cover a dollar unless they are something really special. I agree with whoever said that many of the older books are just as good as the new ones, plus IMO, they are often much more clearly written. I have been collecting technical books, mostly on electronics and photography, for decades See if you can find "Toward Better Photography" by Vincent McGarrett, copyright about 1946 or so. He was my Dad, and he spent a year or more writing the book and took about a thousand pictures. It was commissioned by a magazine called "American Photography," and unknown to him, it was in financial trouble. He took about a thousand pictures, and I helped him develop and print them in our cellar. Because of the financial difficulties, very few of the photographs were printed in the book, and Pop didn't make much money out of it. American Photography went out of business right after that. He became so bummed by it that he hardly took any pictures the rest of his life. --doug
|
Around here, meaning Los Angeles in general, used book stores are getting to be a rarity. Most used books are on the internet. I also buy a lot of books of the non-technical sort, at the bookstores in many public libraries. Mostly not technical books but there are a few. Typically, soft cover are 25c to 50c and hard cover a dollar unless they are something really special. I agree with whoever said that many of the older books are just as good as the new ones, plus IMO, they are often much more clearly written. I have been collecting technical books, mostly on electronics and photography, for decades. Many if not all of them are not on archive sites like archive.org or tubebooks.org (there are others) including some I have never been able to find. Someone else pointed out that the complete set of the Radiation Lab series is available. Don't remember where I saw them but maybe one of the sites above. I have a couple of actual books but have all of them in scanned versions. I also prefer "real" books to the electronic versions but my curiosity is satisfied with whatever feeds information to it. I have a couple of times tried to read a romance novel. I get maybe ten pages into it and the next thing I know is I am startled awake by the book falling on me. There must be people who like them because they seem to sell an awful lot. Perhaps all those sales wind up in the thrift shop. AKA bodice rippers, some fairly well known writers have produced them under pen names. I am addicted to detective stories, there are good ones, although some seem pretty awful. I use them as sleeping pills. Most Good Will stores seem to have mostly old clothes. This is still the -hp-/Agilent/Keysight list I hope, I think I saw a question about a 606A/B go by a while back. Anyway, I couldn't help but comment on this even though its a bit OT.
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Show quoted text
On 11/22/2018 10:15 PM, Dave McGuire wrote: On 11/22/18 7:39 PM, Brad Thompson wrote:
Last stop is your local secondhand shop. But based on what I've seen at Goodwill and Salvation Army stores, most of what gets donated are romance novels... (&) There's definitely a lot of garbage in the book section of most Goodwill stores. I mean, how many copies of the Twilight books did they really print? I think ALL of them are on the shelves of Goodwill stores; apparently even the "tweenagers" bore of them eventually But in Goodwill stores in some geographic areas, there are some goodies to be found. Pittsburgh is an extremely high-tech city...there's a Goodwill store downtown in which my lady and I found a copy of Terman and a few nice books on the 8085 microprocessor this past summer. It's always worth a quick peek. -Dave
-- Richard Knoppow dickburk@... WB6KBL
|
Re: Warning to buy equipment on Ebay on auctions using GSP (global shipping programme)
I once bought some old Fluke?6070A and 6080A signal generators at an online military base auction.? Nothing super high tech: these are 500 MHz and 1 GHz signal generators. To be honest, I wasn't happy with the purchase as the generators were in really poor condition; a fact that wasn't so obvious in the bad quality auction photos.? But, I reluctantly carted them back home and chalked up the experience as a lesson learned.
A year or two later, I received a letter from the auctioneers.? The letter said that my Fluke signal generators were on the ITAR list and it gave me the option of returning them for a full refund.? YES!!!!!!!? Another option was to submit an affidavit stating that the equipment had been disposed of, or destroyed (which wouldn't invoke the refund).? I promptly returned the JUNK for a full refund!
I don't know why such old, obsolete technology was on the ITAR list.? Someone suggested that it might appear on a list of equipment necessary to repair some more complex military hardware, like a radar system or some sort of avionics.
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On 11/22/18 7:39 PM, Brad Thompson wrote: Last stop is your local secondhand shop. But based on what I've seen at Goodwill and Salvation Army stores, most of what gets donated are romance novels... (&) There's definitely a lot of garbage in the book section of most Goodwill stores. I mean, how many copies of the Twilight books did they really print? I think ALL of them are on the shelves of Goodwill stores; apparently even the "tweenagers" bore of them eventually But in Goodwill stores in some geographic areas, there are some goodies to be found. Pittsburgh is an extremely high-tech city...there's a Goodwill store downtown in which my lady and I found a copy of Terman and a few nice books on the 8085 microprocessor this past summer. It's always worth a quick peek. -Dave -- Dave McGuire, AK4HZ New Kensington, PA
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I'd like to call attention to the EEVblog.com forum.
I was put off by Dave's YouTube persona and didn't pay attention to it for a long time. Yes, there is no shortage of Bozos, but it is the damndest collection of PhDs, both papered and common-law I've ever come across on line.
Obviously, anyone with a user name including "Dr" or Wizard" is almost certainly full of BS. But I have verified a number of times by PM that the person did indeed have a PhD, though generally not in EE.
Probably my favorite example was a post entitled, "Has Anyone Built a Mass Spectrometer". The OP is working on a quadrapole mass spec. About the 4th post in was someone who had built two. The first an academic instrument. The second a commercial instrument with a $750K budget.
But there are many more people playing around at that level. So it's a lot of fun. At least if you like hanging out with people who know more than you do. And helping others trying to get there.
There's an amazing thread on building a picoradian tiltmeter using a $12 Chinese vial and a capacitance sensor. Though a slightly more expensive British vial gives better performance because the interior finish on the $12 vials is not very good. These are instruments which placed on a concrete slab have a strong response to walking near it. And register clearly that a car pulled in or out of the driveway from inside the garage.
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Locked
Very OT: A response to Toby
This will not be long, but I'll make a brief comment on my reasoning.
If you look back to the bronze age, that was only possible because there were high tenor (high metal content) ores close to the surface which could be readily mined. And there were abundant trees with which to make charcoal to smelt the ores. Neither of those still exist. The natural resources left whether minerals or fossil fuels are difficult to reach and in the case of metals, *very* low tenor. It takes tens of thousands of people to get a single drop of oil in 9000 ft of water at 30,000 ft BSL. I worked a little bit on St Malo, a Unocal discovery before Chevron bought them. I was riding home on the bus and chatting with a Brit who was subsea systems manager for Jack, a nearby Chevron discovery. All he was responsible for was the equipment that sits on the sea floor and ties in to the production system. He had a $2 billion dollar budget. This was in 2006 or 2007 Jack, St Malo and another field produced first oil in2014. They were discovered in 2003 and 2004. The FSPO (floating storage, production and offloading) system cost $7.5 billion dollars.
How many welders, machinists, fitters and other skilled tradesmen do you think it takes to spend that much money? This was 10 years of intense hard work by a vast number of people. My wild guess is that there were probably about 50-60,000 people involved at some point. Maybe only a few hours like me. All I did was do some synthetic seismograms for the well tie.
If the trucks stop delivering food for a week, there will never be food on the shelves again. Almost everyone has less than a week's supply of food. So it they can get it, they'll stock up as much as possible. In the context of a "just in time" inventory management environment there is *no* capacity for increasing the supply if demand increases. And if demand increases because of a shortage of truck drivers because most of them are sick or dead from influenza, or there has been a Carrington even, a high altitude nuke detonated above the US, a Crater Lake or Yellowstone level caldera collapse or any of a *very* long list of events I can recite., there will be even less capacity to supply food. My doctor, whom I've known since we were 10, tells me people can survive without food for about 60 days.
The net result i will be a period of 30-60 days of incredible violence during which 90% or more of the population will perish. The survivors will be scared and isolated. So social organization will be very difficult.
The Hollywood "Mad Max" version of this is ludicrous. Look at thew costumes. Clothing laced together with leather strips through metal eyelets? Where in the hell are they going to get eyelets? There are no refineries at well sites. There is very little oil left that is not 1000's of ft down. What is left is in places like remote parts of Mynamar.
There was a great article in the Oil and Gas Journal about 15-20 years ago about oil production in the interior. The wells are drilled by setting up a tripod with a pulley. A length of pipe with a beveled edge is attached to a rope. The length of pipe is raised and dropped until it fills with dirt. It is then hauled to the surface, the dirt removed and they start over. Periodically they drop plastic bags off water down the hole as they have found it increases the penetration rate. Once they reach the target, the oil is brought up using a bailer such as the well bucket a childhood friend used to draw water in the 60's.
From there it is transported by young women in 5 gallon jugs to the refinery which consists of a still made from 55 gallon drums.
The wells go dry pretty quickly, so they move over a few feet and rill another one. They even do this "offshore" in a lake using bamboo platforms.
They are very resourceful people, but they are not going to be making semiconductors or machine tools anytime soon unless someone provides a lot of assistance. But those are the only people who have *any* readily recoverable resources. They will survive a collapse of civilization far better than the rest of us. But they will also have no access to the knowledge that makes modern technology possible.
"Oh, but we can use scrap." Oh, yeah? And how many years before all the cars, trucks and other pieces of iron an steel are just brown spots on the ground? Far too low a tenor to be recoverable. A few metals such as gold don't oxidize, but most do. And all the metals important to technology do. Iron is extremely abundant and cast iron is just amazing. It's almost an argument for creationism it's so amenable to primitive methods. But if you don't have high tenor ore, you cannot dig up and smelt an ounce of it. Too much digging and too much tree cutting required.
I got interested in DIY technology around age 20. So at 65, I have spent 45 years trying to prepare for such things. But after reading all those books on the history of technology it sank in that there were two problems: social organization at a large scale (how may people did it take to build the pyramids) and resources which were accessible to technology such as used in Mynamar. Which is only slightly more refined than Drake used in 1859.
I have the tools to do *almost* everything and a library to tell you how. But I'm 65 and have glaucoma. So I'm in a race between dying and going blind. Both my parents lived into their 90's. I hope I do not. I can play guitar and harmonica rather well. Good enough that I can walk on stage and rip a tune with a band I've never played with. But I don't relish the idea of being "Blind Boy Rufus" (I was born with red hair and was given the nickname by my dad. I dropped when I graduated college with my BA in English lit).
I came to realize a few years ago that I am a modern day Noah. I have built an Ark to carry technology. But I have no children and most of the under 30 population considers books as door stops.
So, Toby, that's a short version of why I abandoned the project. It's a very gloomy future. And after 65 years of learning everything (except biological sciences) that I could I can offer no solution. The Silicon Valley elite imagine that when the collapse comes they and their family will get in their personal jet and fly away. Which is possible if they can fly the plane themselves. But the pilot is more likely to shoot the owner and family and take his family than take theirs and leave his own behind.
This is a wretched platform for writing. Doubtless there are many things in my writing which would make me cringe. I took a degree in literature because I wanted a good liberal arts education. The sole criticism I should make of it today is I should have taken math at least up to ordinary differential equations. I did do that later and a *lot* more.
Kids in high school don't learn algebra, geometry and trigonometry because their teachers don't know anything about applying it. But every good skilled tradesman uses them *every* day. And then are insulted because they didn't go to college. It's hard to be motivated to learn something which is difficult if you don't have a clue why you are doing it and neither does the teacher.
I'm going to end it here. Thank you Toby for asking. I hope that at least a few of you found it worthwhile reading.
Reg
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On 11/22/2018 4:03 PM, Mike Feher wrote: Hi Guys – My question is what do I do with all my engineering college texts both undergrad and grad type. They are mainly from the ‘60s and I believe relatively worthless now. I cannot stand to throw them away. Ideas appreciated. – Mike
Hello, Mike-- I volunteer at a local book sale as the sorter/pricer for science and technology books. We typically reject almost all texts, especially older editions and those which have been stricken by the Mad Highlighter (*). Recent editions may get shipped to a used-book wholesaler. Professors may specify that their students use the prof's own text, for which he or she may receive royalties from the publisher-- hence, older editions are no longer welcome and the poor students are out $100 per text or more. For our book sale, I'm free to accept books that I deem saleable or of classic interest (e.g., Terman, Rad Lab, ARRL Handbooks) and I price them inexpensively. The next possible outlet is your local public library, which may have a free-to-take cart. Some libraries charge a small amount for discarded or donated books and may accept your gift books. Local libraries may welcome donations of books that are in good condition for their fundraising sales. Last stop is your local secondhand shop. But based on what I've seen at Goodwill and Salvation Army stores, most of what gets donated are romance novels... (&) 73-- Brad AA1IP (*) The Mad Highlighter typically approaches a textbook with yellow marker in hand and and begins highlighting every other sentence (regardless of content) on page one. Twenty or so pages into the book, the highlighting thins out, and thirty pages in stops altogether.. At that point, it's safe to assume that the luckless book owner has dropped the course.... (&) "Oh, Harold!" she breathed, as he frantically fumbled with the restraining fasteners on her GPIB harness connectors.... [From "Fifty Shades of Gray Pixels"]
|
On Nov 22, 2018, at 11:58 AM, Jeff Kruth via Groups.Io <kmec@...> wrote: Hi Paul! Look them up, there are 28 volumes. They are GREAT! I finally bought a complete set in great condition for 100.00 off a museum Paul, Thanks for your comments on the Rad Lab and its work. The introduction to (at least) one volume tells that “After the cessation of hostilities, many of the scientists and staff “agreed to stay on to document the work” and did so in about 6 to 12 months! In one set of books, we gave to the world the secrets of how to build a radar! The Magic of Microwaves explained!! It seems to me that much of the content would have been classified, especially during the war. I wonder if there was a wholesale classification-release program in effect. ...You can look at Hewlett Packard waveguide instrumentation from the 1950-1990 time frame and see that it is directly derived from the Rad Lad designs with HP niceties added! This phenomenon is parallel to the amateur radio gadgets offered commercially that were taken quite directly from the RCA Hints and GE Ham News publications. Two examples are the Millan 92101 receiver preamplifier and the B&W LPA-1 linear. In a related happening (briefly), General Radio mostly avoided making military-specific equipment. One exception perhaps is the APR-1 and APR-4 ECM receivers. They were developed from a GR instrument meant as a detector/receiver for VHF/UHF/Microwave work, the P-540 receiver. See GR Experimenter March 1947 for further information. Direct link: At least go to the KO4BB website and download the PDF’s. I should download the whole lot as a project. After all, my computer local backup external disk holds TWO TERABYTES, and cost about $80.00. (It is partitioned into 4 separate drives for such purposes.) My personal connection to the Rad Lab was that my EE professor at Tufts (1964-’66) was Prof. Hammond. He’d been at the Rad Lab, and referred to MIT as “Tech”. I have to wonder if he contributed to the books and what he worked on there. Here were guys figuring out how to make all the stuff we use now, and EXPLAINING IT. Indeed: schematics, tube types, resistor and capacitor values (some pulse transformers are mysterious), and so on. My favorite volume is “Vacuum Tube Amplifiers” by Valley and Wallman. I have two examples of tube type IF amplifiers I assume are radar IF strips. The design and implementation of these things are covered in this volume: the technology used to achieve wide bandwidth with proper phase charcteristics involves stagger tuned stages, specific tuned circuit Q values set with parallel resistances and more. I didnt even mention the books on timing, waveforms, vacuum tube circuits, servomechanisms, radomes, so on and so on. Analysis and design of servo systems is a faint memory now, perhaps that is just as well! Long live this fundamental archive of good stuff, and may our interest in it survive long. Roy Roy Morgan K1LKY since 1958 k1lky68@...
|
Réf. : Re: 50 ohm thermocouples was RE: [HP-Agilent-Keysight-equipment] 478A power sensor recal for HP meters (was diode mounts)
may be this news can help
F1CHF
?
?
?
?
?
-------Message original-------
?
Date : 22/11/2018 17:34:46
Sujet : Re: 50 ohm thermocouples was RE: [HP-Agilent-Keysight-equipment] 478A power sensor recal for HP meters (was diode mounts)
?
Thanks Jeff! Nice read.
Best 73 de
Harke
On Thursday, November 22, 2018, 5:30:52 PM GMT+1, Jeff Kruth via Groups.Io <kmec@...> wrote:
The screws are weird!? Back in the late '70's when a 478A head was worth $250 working (real money then!), I used to repair these. I ran a lab at Westinghouse Defense in Baltimore that did MIC work, microwave micro-assembly and wire & ribbon bonding. I used to pay the technicians on their lunch hours to mount salvaged thermistor beads for me. If you blow out a 478A with too much RF, the reference pair is still good. I used to salvage these and match them to the Ref pair in another head, replacing the blown RF pair.? Made a bit of cash that way!
The screws do NOT contact anything, instead they "approach" the thermistor beads, being aligned directly above them. My take on it is that they change the ambient temperature environment by adding a small bit of "hotter" metal closer to the bead, sort of like the DC offset adjustment on an op-amp. However, I could be wrong: instead of adding heat, they may change the reactance of the bead to the chopper frequency, but this seems less likely, as the size is so small (not much capacitance and the frequency of the chopper is low (IIRC, about 10 KHz).
The general failure in adjustment in an attempt to re-calibrate the head is to insert the screw a little too far so that it hits the bead and snaps a wire lead off it.
Hi Paul!? I found that the "driftiness" of the head can sometimes be improved by working the re-balance adjusting the screw pair alternatively, back and forth. 1/8 turn out on one, 1/8 turn in on the other, etc.? YMMV.
I used to leave the head shell off and hold the mount in my hand to heat it, release and watch the behavior of the re-compensated mount as it settles back to ambient. I could get them pretty good after a while.?
Oh well, all that was a really long time ago now, it seems, in a period when I had more time than money, now the other is true. Found a box the other day of a pile of 478 & 8478 guts, left over bits from these days, some beads missing. Off to gold scrap, I guess!
73
J. Kruth
Hi Jeff??
good to talk to you again regarding the 478 and rebalancing the head using the screws
I have found that the temperature? compensation isn’t as good after you have to rebalance using the screws
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By the way never opened the 478? to find out how the screws work
Paul B
In a message dated 11/22/2018 11:01:39 AM Eastern Standard Time, yrrah53@... writes:
Interesting point. I have not worked with thermistor heads since ages but I always wondered how the screws work on the HP478 and HP8478?
73 de
Harke
On Thursday, November 22, 2018, 4:58:38 PM GMT+1, Paul Bicknell <paul@...> wrote:
Hi Jeff??
good to talk to you again regarding the 478 and rebalancing the head using the screws
I have found that the temperature? compensation isn’t as good after you have to rebalance using the screws
?
By the way never opened the 478? to find out how the screws work
Paul B
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From: [email protected] [mailto: [email protected] ] On Behalf Of Jeff Kruth via Groups.Io Sent: 22 November 2018 15:38 To: [email protected] Subject: Re: 50 ohm thermocouples was RE: [HP-Agilent-Keysight-equipment] Issue with homemade diode power sensor for HP meters
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Really? Because HP used the same idea in the 478A & 8478A heads, they were 200 ohms series under AC bias, 50 ohms to RF, but when measured "cold" with an ohm-meter they were approx 3-4K ohms. I would have thought G-M would have used a similar method.
The big thing with the HP heads was the balance between the ref thermistor pair and the measurement thermistor pair. If the measurement pair was damaged by excess RF power, the "rest" resistance was too different from the temperature reference pair (say 7K instead of 4 K). SO you could no longer balance them with the screws.
In a message dated 11/22/2018 9:29:03 AM Eastern Standard Time, paul@... writes:
Regarding the TFT ?Marconi? power meter ?they had 2? thermisters? at 100 ohm each
?And connected so that DC they added up to 200 ohm but presented a 50? to an AC signal
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The power sensor was easily tested as the 2 large pins on the convector should read 200 ohm
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I have such an animal here a GM 460B with that TFT hermocouple. It is an ancient beast. They got bought up by Marconi down the line.
https://patents.google.com/patent/US3384819
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