Keyboard Shortcuts
ctrl + shift + ? :
Show all keyboard shortcuts
ctrl + g :
Navigate to a group
ctrl + shift + f :
Find
ctrl + / :
Quick actions
esc to dismiss
Likes
- TekScopes
- Messages
Search
|
Re: Fair Radio Sales Lima Ohio
I first visited Fair Radio around 1970. A lot of other Ohio based surplus
toggle quoted message
Show quoted text
dealers are long gone.I worked for an asset recovery company in the Orlando area in the early '90s. Part of the business was to sell scrap mainframe boards to IC recovery businesses. The people that ran these companies were mostly stupid. The would measure the remaining length of IC leads on the solder side of boards, and reject most of them as too short to reuse. Thes boards were almost as thick as the tapered part of the pins were long, so I started recovering and selling popular ICs to our regular customers. The only condition was that they had to buy entire tubes of one part number. I could recover, and retin the leads of several thousand DRAMs per day. We sold them for $2.75 each. The IC recovery companies had turned them down at 15 cents each. The same for common EPROMs at the time. They offered a nickel, each for the few that they bought. I sold them for $1.50 each. Just those two groups supported a lot of small computer stores, and development companies. As stated above, most people have no clue of the value of surplus. A lot of businesses were started from WW-II surplus, Millions were made from what most thought was trash. The termination of many government contracts dumped billions of components on the surplus market. Many claimed that early Heathkit scopes were built from mostly surplus, and some parts had a pre war look to them. A lot of kids went into Electronics because of the availability of cheap surplus components. On Fri, Nov 27, 2020 at 8:21 PM Tim Laing <laingt@...> wrote:
Hello, I live about 2 miles from Fair radio. I know the owner Phil, not a |
|
Re: 528A TV waveform monitor.
There were several Tektronix TV studio vectorscopes. They were of three designs- stand alone, high precision like the 520, smaller simpler and less precise self contained models with the color decoder built in for use with video recorders, and simple X-Y displays like the 602 that had no decoding circuitry and were used in video recorders and with video monitors like the 650. Most you will find will have been on constantly for years and the jugs will take fifteen minutes to come up to their best brightness. They are not of much use for anything besides monitoring 480 I video, but if you collect and restore older studio equipment they are all quite useful. VHS and even old DVDs are having a quiet resurgence in popularity, and these monitors are valuable for working with this older equipment. Try to find them a home instead of trashing them.
toggle quoted message
Show quoted text
Bruce Gentry, KA2IVY On 11/27/20 5:30 PM, Ed Breya via groups.io wrote:
I just took a quick look at the 528 on tekwiki. As it is, it's pretty much only good for the original purpose. But, it appears to have an electrostatic deflection CRT (since it's basically a scope, not a TV display, which would tend to use raster-scan), so you could convert it to a nice little low speed X-Y monitor, with simple changes to the guts, if you're so inclined, and need such a thing. I don't know if the graticule is built into the CRT face (probably) - if so, you'd be stuck with the IRE etc scales, instead of a nice grid. If you really want to fix and make it into an X-Y monitor, you can probably find some Tek scope or other CRT that is the same except for the faceplate, and swap it in. |
|
Re: Fair Radio Sales Lima Ohio
When I started going to surplus stores in the mid to late 70's, we had many options.? The best was Haltek.? Being in Mountain View, it was full of both ancient (to me) oddities, and recent scrap.? When I was building my first PET computer from scrap, I needed "storage", and Haltek just happened to have a large box of Commodore cassette drives and some test shot or prototype cases. I even sold them some of my findings.??
toggle quoted message
Show quoted text
They are long gone, as are Allied Electronics in Palo Alto (the junk store, not the disty), two places in Sunnyvale I can barely recall, Halted (Haltek's overpriced competition; which moved a while back, then closed.? Apparently they are open again, having been sold to Excess Solutions); Even the newer Weird Stuff is gone, but I rarely found anything I was looking for there.? I have vague memories of short-lived stores further south too.? Rents are so high now that an existing store would need to own it's building outright and sell a lot of material just to survive.? Most people want shiny, new things these days, not dusty old scrap. -Dave On Friday, November 27, 2020, 08:12:36 PM PST, ken chalfant <kpchalfant@...> wrote:
Greetings, I feel like I¡¯m jumping in somewhere in the middle of this story (thread), but I can¡¯t help it.? This sounds all too familiar. I live in Colorado Springs, Colorado.? There has been a ¡°surplus¡± electronics store here for 34 years and I have been a customer for all that time.? It¡¯s funny now that I think about it.? I was 34 when they opened, now I¡¯m not. Anyway, they started trying to go out of business in mid to late 2019 and finally managed to close the doors for the last time just a couple of weeks ago.? That store was priceless to me and others and it is a great loss although many may never realize that.? For years I cared for old, obsolete printing equipment as well as other machines and equipment.? Often what had failed on a machine was as obsolete as the machine itself.? On very rare occasions I would find the exact - otherwise unobtainable part - waiting for me on a shelf.? Other times I would stand there in an aisle and design a repair solution from what lay before me. If I hadn¡¯t kept those old machines running people would have lost their jobs. Now that store is gone - forever. Funny though, in the last fleeting moments I couldn¡¯t let it all go so I bought all the semiconductors.? I don¡¯t even know yet what I have, but the store owner guessed I bought about 100,000 individual parts.? Fortunately, it was all in bin boxes but even so it required two full loads of a topper covered 3/4 ton truck and about 5 loads of my topper covered smaller truck. Crazy huh¡ I have known about Fair Radio as far back as I can remember and I have purchased a few items over the years. I think these stores are far more important than most realize.? Not everything in the world is shiny new and a lot of people depend on some very old and sometimes very tired ¡°things¡± to keep their lives moving forward and even the thought of another such place approaching the end of the line is very, very sad. Forgive my use of our bandwidth to take a walk down memory lane. Regards, Ken On 27Nov, 2020, at 6:21 PM, Tim Laing <laingt@...> wrote: |
|
Re: Fair Radio Sales Lima Ohio
Greetings,
toggle quoted message
Show quoted text
I feel like I¡¯m jumping in somewhere in the middle of this story (thread), but I can¡¯t help it. This sounds all too familiar. I live in Colorado Springs, Colorado. There has been a ¡°surplus¡± electronics store here for 34 years and I have been a customer for all that time. It¡¯s funny now that I think about it. I was 34 when they opened, now I¡¯m not. Anyway, they started trying to go out of business in mid to late 2019 and finally managed to close the doors for the last time just a couple of weeks ago. That store was priceless to me and others and it is a great loss although many may never realize that. For years I cared for old, obsolete printing equipment as well as other machines and equipment. Often what had failed on a machine was as obsolete as the machine itself. On very rare occasions I would find the exact - otherwise unobtainable part - waiting for me on a shelf. Other times I would stand there in an aisle and design a repair solution from what lay before me. If I hadn¡¯t kept those old machines running people would have lost their jobs. Now that store is gone - forever. Funny though, in the last fleeting moments I couldn¡¯t let it all go so I bought all the semiconductors. I don¡¯t even know yet what I have, but the store owner guessed I bought about 100,000 individual parts. Fortunately, it was all in bin boxes but even so it required two full loads of a topper covered 3/4 ton truck and about 5 loads of my topper covered smaller truck. Crazy huh¡ I have known about Fair Radio as far back as I can remember and I have purchased a few items over the years. I think these stores are far more important than most realize. Not everything in the world is shiny new and a lot of people depend on some very old and sometimes very tired ¡°things¡± to keep their lives moving forward and even the thought of another such place approaching the end of the line is very, very sad. Forgive my use of our bandwidth to take a walk down memory lane. Regards, Ken On 27Nov, 2020, at 6:21 PM, Tim Laing <laingt@...> wrote: |
|
Re: 528A TV waveform monitor.
If it was in use at a TV station, the CRT is probably shot.
toggle quoted message
Show quoted text
The only use that I know of for this specialized scope is to monitor analog video to set levels and for signal verification. It has use in amateur TV or if you are recording analog video. Glenn On 11/27/2020 3:19 PM, Roy Thistle wrote:
Hi All: --
----------------------------------------------------------------------- Glenn Little ARRL Technical Specialist QCWA LM 28417 Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178 QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR "It is not the class of license that the Amateur holds but the class of the Amateur that holds the license" |
|
Re: Resistor in series
Dennis,
toggle quoted message
Show quoted text
I saw similar things when I was working on Silicon Valley 700W FM amplifiers. The physical orientation of the ATC caps was critical. We noted that sometimes two or three caps needed to be placed on edge or even stacked on top of each other. RF is always fun but this added a new twist. Regards, Stephen Hanselman Datagate Systems, LLC On Nov 27, 2020, at 14:50, Dennis Tillman W7pF <dennis@...> wrote: |
|
Re: (OT) Where to go for 70s IBM hardware? I'm looking for a terminal.
In addition, smartphones use Wi-Fi and other comms methods to navigate.? Much superior to those TomTom boxes that only used GPS.JimSent from my Verizon, Samsung Galaxy smartphone
toggle quoted message
Show quoted text
-------- Original message --------From: stevenhorii <sonodocsch@...> Date: 11/27/20 3:54 PM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] (OT) Where to go for 70s IBM hardware? I'm looking for a terminal. Jim,Yep. I'm pretty sure the navigation system in my car uses GPS primarily butmust have a dead reckoning system as it shows me where I am when I amdriving through an underground tunnel. The system updates as soon as theGPS signals are again available, so there are sometimes funny jumps fromshowing me somewhere off the highway to back on it. GPS-aided inertialseems to be the way many navigation systems are being designed.On Fri, Nov 27, 2020 at 6:46 PM Jim Ford <james.ford@...> wrote:> FWIW inertial navigation systems and GNSS (Global Navigation Satellite> Systems) are complementary.?? INS tend to drift over time, and GNSS provide> corrections.? Navigation in GNSS-denied or -degraded areas is a whole other> ballgame.Jim Ford? Sent from my Verizon, Samsung Galaxy smartphone> -------- Original message --------From: stevenhorii <sonodocsch@...>> Date: 11/27/20? 1:04 PM? (GMT-08:00) To: [email protected] Subject: Re:> [TekScopes] (OT) Where to go for 70s IBM hardware? I'm looking for a> terminal. Harvey and Bill,Yes - I've tried that trick. For small gyros it> works. Gyros with electricspin motors tend to draw the most current at> startup as do most motors.After that, the current usually drops quite a> bit. Some of the 400Hz gyrosuse two-phase power. The usual trick is to put> a capacitor across the twospin motor inputs - it provides the phase lag for> the second phase. I haveNOT tried this, but I have seen some gyros -> usually the small ones thatare about one-inch in diameter and three inches> long and almost always rategyros - that had a phase-splitting capacitor> already soldered in place.This white paper describes a basic 2-phase power> supply for gyro spinmotors:> > was fortunate - at a hamfest years ago, I picked up a couple of> AbbottTransistor Labs inverters. These took 24-28 VDC and output AC 400Hz> singlephase at up to about 2 amps. Not enough to run a large gyro, but> enough forthe smaller ones. I even ran a fairly large gyro - a Honeywell> rate gyro -with one of these. They do need a heatsink.I sometimes do an> eBay search for "Behlman Invertron" as they made somevery useful frequency> converters - 115 VAC to variable 400Hz AC. Some werevariable frequency and> some versions also had single to three-phase output.They tend to be> expensive (and heavy for the higher output ones) and Inever managed to find> one at what I thought was a reasonable price. Someversions had> interchangeable plug-in oscillators so you could run evenhigher frequency> AC devices (some gyros use 800 Hz - the Apollo programgyros ran with 800> Hz, 2-phase power). There are currently a couple ofBehlman Invertrons on> eBay, though they are not cheap.If you can find them, some of the WW II and> even early missile (Nike) gyrosran on DC (24-28 v). Those are fun to run> up. However, I've had some forwhich the bearings almost certainly were bad> - they were very noisy whenrunning and spin-down after power was removed> was quite fast. Likely whythey were surplus.Years ago, a surplus dealer on> Canal Street in NYC sold me a WW II Bendixvertical gyro. It was a 400Hz> gyro and he told me I could run it on 60Hz ACby putting a current limiting> incandescent lamp (no choices - there were noLED lamps then) in the power> circuit and running at a lower voltage via aVariac. I did not have the guts> to try it, but I do know those who did andsaid it works, but you will not> get the gyro up to full speed.Messing about with gyros can lead you down a> deep hole much as gettingfascinated by Tektronix equipment and then> desiring to get some (plusspares "for parts" and all the manuals). Now you> can get fairly accurategyros made using IC fab techniques - the MEMS units.> These things live insmart phones and tablets now. These plus GPS have> radically changedinertial navigation. Fun stuff, though.Steve H.On Fri, Nov> 27, 2020 at 1:52 PM Harvey White <madyn@...> wrote:> Hi-fi> amplifier of sufficient output capability driven by a sinewave> generator> sitting at 400 Hz?>> Harvey>> On 11/27/2020 11:52 AM, Bill E wrote:> > Even> though way off the off topic topic (parse that), still a fun> discussion. I> scored a box of 10 real gyros and logic pulled from DC-10s.> Cute little> rate gyro, etc. Problem is, all that stuff takes 28v 400Hz.> Haven't gotten> around to making a power supply for them yet.> >> >> >> >> >> >>>> >>>>> >>>
|
|
Fair Radio Sales Lima Ohio
Hello, I live about 2 miles from Fair radio. I know the owner Phil, not a close friend though. I am not sure what will happen when he retires....
I do not know if the show room is open to the public at this time. I can do some checking. I can stop in but if I do I generally need to have at least 2 hours free to wander around and get my fix.... I have gone there on missions for other people in the past. I could check on plug ins. My first visit was probably when I was 13 or 14 years old, I am 59 now. I took my future wife to Fair Radio on our first ¡°date¡±. Maria and I are still Married going on 31 years. Prices are not cheap but he has a lot of overhead costs. I have a bunch of pictures that I have taken there in the past, I am afraid of the day I find out they are closing. I wish I had taken pictures in the old dairy buildings located on Eureka Street. Tim Laing |
|
Re: Different Versions of XYZs of Oscilloscopes
Roy Thistle wrote:
The copy I have, from '81, is also well written as well as being beautifully illustrated and typeset. If you have a copy illustrated with 500 series scopes, then the document must date back to at least the mid-70s. I would be really jazzed if I could find a copy (printed or electronic) that used the 400 series scopes as examples. The discussion of the delayed time base, alone, would make it worthwhile. My copy has a fold-out sheet as the back cover with a photo of the 2213 as its subject, and I've got a version on order that uses the 2213A in the same way (copyright 1985). None of the PDFs that I've seen, even those that appear to be scans of the 1981 version, have included scans of the back cover fold-out. -- Jeff Dutky |
|
Re: Different Versions of XYZs of Oscilloscopes
On Fri, Nov 27, 2020 at 03:13 PM, Jeff Dutky wrote:
There are different "versions" of the "book" (They are more like primers, or some kind of sales tool/handout for Tektronix sales engineers) By "versions" I mean primers/books/sales-tools which are in the same vein, and have the title "The XYZs of..." As in Tektronix(1993)The XYZs of Analog and Digital Oscilloscopes(070-8690-01). Tektronix(1981)The XYZs of Using a Scope(). IMO, the watershed, for classical Tektronix copy, happens when they start to mention digital oscilloscopes. Somewhere, I have a very old one of these... something a Tek sales-person could give to a potential customer... who was mostly clueless about oscilloscopes... but could get an "understanding" by reading through it. If I'm thinking right... that one is illustrated with 500 series scopes. It's not only a masterpiece of typesetting, and graphic arts... it's clearly and informatively written too. |
|
Re: (OT) Where to go for 70s IBM hardware? I'm looking for a terminal.
I suspect that the same "I'm on a road, I must stay on a road because a car doesn't go off a road" algorithm that keeps the fifty foot uncertainty (or so) invisible to the operator.
toggle quoted message
Show quoted text
To test this out, test on a route that takes a diverging exit off a turnpike/freeway/etc.? Don't take that exit and see where the autopilot thinks you're going, Harvey On 11/27/2020 6:54 PM, stevenhorii wrote:
Jim, |
|
Re: (OT) Where to go for 70s IBM hardware? I'm looking for a terminal.
Jim,
toggle quoted message
Show quoted text
Yep. I'm pretty sure the navigation system in my car uses GPS primarily but must have a dead reckoning system as it shows me where I am when I am driving through an underground tunnel. The system updates as soon as the GPS signals are again available, so there are sometimes funny jumps from showing me somewhere off the highway to back on it. GPS-aided inertial seems to be the way many navigation systems are being designed. On Fri, Nov 27, 2020 at 6:46 PM Jim Ford <james.ford@...> wrote:
FWIW inertial navigation systems and GNSS (Global Navigation Satellite |
|
Re: (OT) Where to go for 70s IBM hardware? I'm looking for a terminal.
Bill,
toggle quoted message
Show quoted text
A really good book on the history of inertial navigation and the impact it had - somewhat frightening in that improvements actually made the use of nuclear weapons easier to imagine on the part of military folks - is fascinating. It's called "Inventing Accuracy" by Donald MacKenzie. There is also an out-of-print series I would love to find - it came from the AGARD folks and is a history of gyroscopes. I have one volume, but I think there were three of them. I like mechanical gyros as well. The problems the engineers had to face - mostly to do with bearings and maximizing angular momentum while keeping the weight reasonable - tend to cross multiple engineering disciplines from metallurgy to materials science, not ignoring how to make the things and the electronics of picking off the signals. The amazing gyros to me are the gas-bearing ones. No metal bearings to wear out, though I wonder about dealing with the bearings before spin up (at least for the hydrodynamic bearings that need to spin to produce the film of gas that keeps the bearing surfaces from contacting each other). The G300 gyro from Litton had a gas bearing wheel. It's a beautiful gyroscope - almost all beryllium so manufacturing them must have been a challenge. Many were scrapped by surplus folks for the beryllium and the small gold alloy balance weights on the float assembly. They were very widely used - commercial aircraft (the Litton LTN-51) and numerous military aircraft. The one inertial instrument I would love to find is a gyro-accelerometer. These use an unbalanced gyro and the torque it generates with acceleration. I believe the Saturn V used them in the inertial platform. I think some of the later strategic missiles do as well - the MX/Peacekeeper comes to mind. I did set up one of the DC gyros - surplus from the Nike missile - to look at the output. Bringing this back to a Tek thread, the output of that gyro was a change in resistance. So putting the pickoff resistor in a simple circuit to change an output voltage from a power supply and I looked at the output on a Tek scope. If I recall, I did this with a 547 that I had. The gyro was a rate gyro. I don't have a rate table, but it was fun to twist the thing around and watch the scope trace out the rate it sensed. The gyros with the synchro outputs are more difficult to deal with. An engineer I was working with at the time went a little further - he sent my gyro circuit output to an opamp and then digitized that output with an A-D converter. More circuitry, but not as much fun as simply looking at the output in real-time on the scope. I was writing code in the days of punched cards (spent many hours at an IBM 026 and later, an 029 keypunch machine) and waiting for my output after submitting my card deck. FORTRAN on an IBM 7094. Later, I ran code on a PDP-8 and on a PDP-11. I used DEC Vax machines, but by that time, often just running my data on application software, not writing my own code. I spent hours at an ASR-33 teletype running timeshared stuff on a DECSystem 10. I don't miss punching cards or batch processing computer jobs, but it makes for great stories to share. My young colleagues regard some of those stories I am sure like we did when our parents told us about having to walk to school even when it snowed, writing homework longhand, and doing their math problems with pencil and paper. I tell the young folks that their smartphones are many times more powerful than the computer that got us to the moon. Steve H. On Fri, Nov 27, 2020 at 6:05 PM Bill E <solartron@...> wrote:
MEMS? Dang newfangled stuff. Give me rotating mass any time. :) The DC-10 |
|
Re: (OT) Where to go for 70s IBM hardware? I'm looking for a terminal.
FWIW inertial navigation systems and GNSS (Global Navigation Satellite Systems) are complementary.? ?INS tend to drift over time, and GNSS provide corrections.? Navigation in GNSS-denied or -degraded areas is a whole other ballgame.Jim Ford??Sent from my Verizon, Samsung Galaxy smartphone
toggle quoted message
Show quoted text
-------- Original message --------From: stevenhorii <sonodocsch@...> Date: 11/27/20 1:04 PM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] (OT) Where to go for 70s IBM hardware? I'm looking for a terminal. Harvey and Bill,Yes - I've tried that trick. For small gyros it works. Gyros with electricspin motors tend to draw the most current at startup as do most motors.After that, the current usually drops quite a bit. Some of the 400Hz gyrosuse two-phase power. The usual trick is to put a capacitor across the twospin motor inputs - it provides the phase lag for the second phase. I haveNOT tried this, but I have seen some gyros - usually the small ones thatare about one-inch in diameter and three inches long and almost always rategyros - that had a phase-splitting capacitor already soldered in place.This white paper describes a basic 2-phase power supply for gyro spinmotors: was fortunate - at a hamfest years ago, I picked up a couple of AbbottTransistor Labs inverters. These took 24-28 VDC and output AC 400Hz singlephase at up to about 2 amps. Not enough to run a large gyro, but enough forthe smaller ones. I even ran a fairly large gyro - a Honeywell rate gyro -with one of these. They do need a heatsink.I sometimes do an eBay search for "Behlman Invertron" as they made somevery useful frequency converters - 115 VAC to variable 400Hz AC. Some werevariable frequency and some versions also had single to three-phase output.They tend to be expensive (and heavy for the higher output ones) and Inever managed to find one at what I thought was a reasonable price. Someversions had interchangeable plug-in oscillators so you could run evenhigher frequency AC devices (some gyros use 800 Hz - the Apollo programgyros ran with 800 Hz, 2-phase power). There are currently a couple ofBehlman Invertrons on eBay, though they are not cheap.If you can find them, some of the WW II and even early missile (Nike) gyrosran on DC (24-28 v). Those are fun to run up. However, I've had some forwhich the bearings almost certainly were bad - they were very noisy whenrunning and spin-down after power was removed was quite fast. Likely whythey were surplus.Years ago, a surplus dealer on Canal Street in NYC sold me a WW II Bendixvertical gyro. It was a 400Hz gyro and he told me I could run it on 60Hz ACby putting a current limiting incandescent lamp (no choices - there were noLED lamps then) in the power circuit and running at a lower voltage via aVariac. I did not have the guts to try it, but I do know those who did andsaid it works, but you will not get the gyro up to full speed.Messing about with gyros can lead you down a deep hole much as gettingfascinated by Tektronix equipment and then desiring to get some (plusspares "for parts" and all the manuals). Now you can get fairly accurategyros made using IC fab techniques - the MEMS units. These things live insmart phones and tablets now. These plus GPS have radically changedinertial navigation. Fun stuff, though.Steve H.On Fri, Nov 27, 2020 at 1:52 PM Harvey White <madyn@...> wrote:> Hi-fi amplifier of sufficient output capability driven by a sinewave> generator sitting at 400 Hz?>> Harvey>> On 11/27/2020 11:52 AM, Bill E wrote:> > Even though way off the off topic topic (parse that), still a fun> discussion. I scored a box of 10 real gyros and logic pulled from DC-10s.> Cute little rate gyro, etc. Problem is, all that stuff takes 28v 400Hz.> Haven't gotten around to making a power supply for them yet.> >> >> >> >> >> >>>> >>>
|
|
Re: Resistor in series
Bob Albert wrote:
Here's an oral history video discussing the history of industrial design at Tek: The speaker is the former head of industrial design at Tek (Gale Morris) and he mentions (possibly hyperbolically) that the 453 sold 70,000 units in a single shot to IBM, so the pennies can really add up. -- Jeff Dutky |
|
Different Versions of XYZs of Oscilloscopes
I have a copy of The XYZs of Oscilloscopes that appears to have come with an early 2213, but I have seen PDFs with the same title with much later copyright dates, and have seen similar for sale online.
My question is how many different versions were there of this book? The one I have discusses both the 2213 and 2215, but uses pictures of the 2213 in almost all the examples (except for one that illustrates the dual time base, which the 2213 doesn't have). Were there different versions of the book produced for the different scopes in 2200 series? Were there versions of the book for the 400 series scopes (or the 2400 series)? -- Jeff Dutky |
|
Re: (OT) Where to go for 70s IBM hardware? I'm looking for a terminal.
MEMS? Dang newfangled stuff. Give me rotating mass any time. :) The DC-10 gyros I have (part of the fight stability system) are 2 phase, but have a phase-shift cap. I've managed to spin up a few using random hackery (old audio amp, TEK frequency synthesizer, some fets, not pretty). They are amazingly sensitive. Interestingly, if you're an INS nerd, the gyros are set up for strapdown, but they just run using an analog resolver. I have a breadboarded inverter I never finished because we were moving. Giving me incentive to pick that project up again. As for 'bad' bearings, frequently because of hardened lubrication. If you're daring, dismantle, use some new lube, all set to go.
Ok, to bring more back on topic, did Tek have any INS plugins for the TM500x frames? (of course not, but hey, I can dream) Bill PS - if this is going to be a continuing OT thread, maybe a name change? OTOH, I did use a lot of IBM hdw back in the '70s. IBM 1130, 360, 370, card punches, etc. Something I've managed to mostly forget. BALR! Also DEC 6, 8, 10, and 11. Spacewar on the 6 at the MIT AI lab, classic :) Even more so, Mazewar on the 10/Imlacs. I have an 8 replica running OS/8 and an 11 replica running RSX, with real blinking lights and switches, in my living room. Oh, and a random assortment of TMS plugins, and several 2465's, last of the truly great analog scopes. |
|
Re: Resistor in series
Bob Albert
Les obvius is that the engineer had stock in a resistor company/? Sure, a resistor is only 2? but multiply that by 1000 and you get into some real money,
toggle quoted message
Show quoted text
On Friday, November 27, 2020, 02:50:13 PM PST, Dennis Tillman W7pF <dennis@...> wrote:
There is another explanation for doing something like this which is not as obvious. If you look at the schematic for the 067-0681-01 Tunnel Diode Pulse Generator designed by John Addis at Tektronix There are three 1/8W 1Kohm resistors (R4, R5, and R6) connected in series going to the tunnel diode. Several years ago I asked him why he did not use one 3Kohm resistor instead. What he knew and I learned was that the body capacitance of each of these 3 resistors in series was far less than the body capacitance of one 3Kohm resistor. The TD is being driven by the collector of the transistor which is high impedance, and the three 1Kohm resistors in series reduces the time constant of the pulse going to the Tunnel Diode without adding any additional capacitance across the Tunnel Diode that would slow it down. I doubt this had anything to do with Tek portable scopes since their frequency response is almost two orders of magnitude slower than the fast edge of the Tunnel Diode Pulse Generator but sometimes there are other explanations for why you might encounter things that are not obvious. Dennis Tillman W7pF -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Milan Trcka Sent: Tuesday, November 24, 2020 9:09 PM To: [email protected] Subject: Re: [TekScopes] Resistor in series Jeff, the resistors connected end to end are an attempt to make a required resistance that was not available as a standard resistor value. Shortage of parts? Engineering change? Select in test? Who knows. I have a few of those in my 453 scope. -- Dennis Tillman W7pF TekScopes Moderator |
|
Re: Resistor in series
There is another explanation for doing something like this which is not as obvious.
toggle quoted message
Show quoted text
If you look at the schematic for the 067-0681-01 Tunnel Diode Pulse Generator designed by John Addis at Tektronix There are three 1/8W 1Kohm resistors (R4, R5, and R6) connected in series going to the tunnel diode. Several years ago I asked him why he did not use one 3Kohm resistor instead. What he knew and I learned was that the body capacitance of each of these 3 resistors in series was far less than the body capacitance of one 3Kohm resistor. The TD is being driven by the collector of the transistor which is high impedance, and the three 1Kohm resistors in series reduces the time constant of the pulse going to the Tunnel Diode without adding any additional capacitance across the Tunnel Diode that would slow it down. I doubt this had anything to do with Tek portable scopes since their frequency response is almost two orders of magnitude slower than the fast edge of the Tunnel Diode Pulse Generator but sometimes there are other explanations for why you might encounter things that are not obvious. Dennis Tillman W7pF -----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Milan Trcka Sent: Tuesday, November 24, 2020 9:09 PM To: [email protected] Subject: Re: [TekScopes] Resistor in series Jeff, the resistors connected end to end are an attempt to make a required resistance that was not available as a standard resistor value. Shortage of parts? Engineering change? Select in test? Who knows. I have a few of those in my 453 scope. -- Dennis Tillman W7pF TekScopes Moderator |
Michael A. Terrell
Tim Laing
to navigate to use esc to dismiss