From 2014: Tektronix Announces Winner of Europe’s Oldest Working Oscilloscope Contest
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Kevin Wood G7BCS
Exactly the same story with my 546, but with a different ending. It was donated to the school by the local Marconi factory and sat in the science lab at school gathering dust for several years while we used the basic junk that the school was issued.
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Eventually I asked why it was never used. Too many knobs! Nobody could understand it. I made a cheeky offer and it came home in my mother's wheelbarrow! 30+ years later and with the benefit of one of Chuck's transformers it still works very nicely! Kevin G7BCS
On 16/09/2019 21:57, Dave Wise wrote:
Closest I got was high school (Benson Polytechnic in Portland OR) in the early 70's, where one electronics classroom had a 514D in a back corner. I always felt sorry for the poor old thing, which was never touched as far as I know. Also covetous; but the teacher wouldn't give it up. It was the best instrument in the room, our assigned tools being RCA service-grade boxes.
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Chuck Harris
:-)
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Kevin Wood G7BCS wrote:
Exactly the same story with my 546, but with a different ending. It was donated to
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Chuck Harris
The old 500 series worked quite differently from what
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became the standard analog scope interface, the 545. The vertical amplifier, and attenuator wasn't calibrated, so to make things work, you adjusted the vertical amplifier variable attenuation to exactly fit the waveform on the graticule lines. Then you switched the vertical input to the calibrator, and adjusted it to match the same graticule lines... reading the peak-peak voltage off of the calibrator's pointer dial. The horizontal time was similarly odd.... but at least it was calibrated to the graticule. The main time switch selected the decade you were in: 1000us, 100us, 10us, 1us, 0.1us per cm. The secondary time switch was a two dial multiplier, that had 0-10 on one dial, and 0-0.9 on the second. Typically, you adjusted the timing so that you had one cycle on the graticule, and read the time off of the dials. -Chuck Harris OBTW, the HV section was in a sealed can full of oil. Which was a good thing for the bumble bee capacitors in it, but not too convenient when a 5642 rectifier burned out. You unscrew the HV insulators, to keep the pressure down, unsolder the can lid, and extract the HV section. It is exactly the same configuration as all of the later 500 series, only the HV transformer is the much larger 2.75" W5 E core... and ran at 400Hz, as I recall... maybe 1KHz. Dave Wise wrote:
Closest I got was high school (Benson Polytechnic in Portland OR) in the early 70's, where one electronics classroom had a 514D in a back corner. I always felt sorry for the poor old thing, which was never touched as far as I know. Also covetous; but the teacher wouldn't give it up. It was the best instrument in the room, our assigned tools being RCA service-grade boxes.
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Dave Wise
< The vertical amplifier, and attenuator wasn't calibrated, so to make things work, you adjusted the vertical amplifier variable attenuation to exactly fit the waveform on the graticule lines. Then you switched the vertical input to the calibrator, and adjusted it to match the same graticule lines... reading the peak-peak voltage off of the calibrator's pointer dial.>
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Thanks for explaining that so clearly. I suppose that using the graticule as a transfer standard was a good idea back when the amp and CRT deflection were not so linear. I used to think "calibrated graticule" was just marketing. I didn't realize it was an inversion of methodology. Still, if they gave me one now, I'd be happy to fix it and play with it, oil can and all. Dave Wise
-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Chuck Harris Sent: Monday, September 16, 2019 2:38 PM To: TekScopes@groups.io Subject: Re: [TekScopes] From 2014: Tektronix Announces Winner of Europe’s Oldest Working Oscilloscope Contest The old 500 series worked quite differently from what became the standard analog scope interface, the 545. The vertical amplifier, and attenuator wasn't calibrated, so to make things work, you adjusted the vertical amplifier variable attenuation to exactly fit the waveform on the graticule lines. Then you switched the vertical input to the calibrator, and adjusted it to match the same graticule lines... reading the peak-peak voltage off of the calibrator's pointer dial. The horizontal time was similarly odd.... but at least it was calibrated to the graticule. The main time switch selected the decade you were in: 1000us, 100us, 10us, 1us, 0.1us per cm. The secondary time switch was a two dial multiplier, that had 0-10 on one dial, and 0-0.9 on the second. Typically, you adjusted the timing so that you had one cycle on the graticule, and read the time off of the dials. -Chuck Harris OBTW, the HV section was in a sealed can full of oil. Which was a good thing for the bumble bee capacitors in it, but not too convenient when a 5642 rectifier burned out. You unscrew the HV insulators, to keep the pressure down, unsolder the can lid, and extract the HV section. It is exactly the same configuration as all of the later 500 series, only the HV transformer is the much larger 2.75" W5 E core... and ran at 400Hz, as I recall... maybe 1KHz. Dave Wise wrote: Closest I got was high school (Benson Polytechnic in Portland OR) in the early 70's, where one electronics classroom had a 514D in a back corner. I always felt sorry for the poor old thing, which was never touched as far as I know. Also covetous; but the teacher wouldn't give it up. It was the best instrument in the room, our assigned tools being RCA service-grade boxes.
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Dave Seiter
What kind of oil was used? I ask because one of mine (I think the 511a) seemed like it was filled with wax, or at least what leaked out long ago looks/feels like wax. What was the reason for burying the HV in oil? One of these days I'm going to have to open both of them up because neither works.
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On Sep 16, 2019, at 3:13 PM, Dave Wise <david_wise@...> wrote:
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Chuck Harris
They were loaded with oil/paper capacitors, known as
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bumble bee type capacitors... all leaky, both physically, and electrically. They were also loaded with 20uf/20uf - 450V Sprague FP can type capacitors... one for each tube's screen. All leaky. And, they had wafer switches, which were often sprayed to dripping by some user at some point. The HV was in an oil filled can, which would leak if the scope was stored on its side... but shouldn't if it was stored upright. The ceramic insulators were the seal. -Chuck Harris Dave Seiter wrote:
What kind of oil was used? I ask because one of mine (I think the 511a) seemed like it was filled with wax, or at least what leaked out long ago looks/feels like wax. What was the reason for burying the HV in oil? One of these days I'm going to have to open both of them up because neither works.On Sep 16, 2019, at 3:13 PM, Dave Wise <david_wise@...> wrote:
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Chuck Harris
The 513D HV module is a little different from the 511, as
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I recall, with the 511 having a bolt on top... and the 513 having a solder on top. The 513D's oil is about an SAE30 transformer oil, smells heavy of bakelite, or micarta, but not of PCB. I was told years ago by someone at tek, that it was just mineral oil. I would imagine the 511 used the same. As to why, they didn't want the whole thing to arc over. You can have electrodes much closer together when you use a material with a high dielectric strength, like oil, than you can when you use simply air. I can't make any promises, but I think I still have the innards of a bad 513D HV module. If I do, I will take some pictures. I'm not sure when I will do this, but I will add it to my mental calendar. -Chuck Harris Dave Seiter wrote:
What kind of oil was used? I ask because one of mine (I think the 511a) seemed like it was filled with wax, or at least what leaked out long ago looks/feels like wax. What was the reason for burying the HV in oil? One of these days I'm going to have to open both of them up because neither works.On Sep 16, 2019, at 3:13 PM, Dave Wise <david_wise@...> wrote:
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