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1502: Difference between revisions
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Fixed typos, added CT100 link,
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The first version used a CRT and is an almost completely analog design except for some discrete digital | The first version used a CRT and is an almost completely analog design except for some discrete digital | ||
logic used to pre-fire and fire the [[tunnel diodes|tunnel diode]] pulser. The later models (1502B/C) | logic used to pre-fire and fire the [[tunnel diodes|tunnel diode]] pulser. The later models (1502B/C) | ||
used a liquid-crystal display and a microprocessor. | used a liquid-crystal display and a Z80 microprocessor. | ||
The other major difference between versions is the line charging method. | The other major difference between versions is the line charging method. | ||
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''[http://www.ise.pw.edu.pl/~tomi/papers/wilga2006_50ps.pdf Low cost programmable pulse generator with very short rise/fall time]''. | ''[http://www.ise.pw.edu.pl/~tomi/papers/wilga2006_50ps.pdf Low cost programmable pulse generator with very short rise/fall time]''. | ||
There appears to have been an optional "static suppressor" in a BNC M-F package, Tek [[011-0132-00]], used to protect the sampler and TD. It's pretty obscure. The BNC connector on later 1502s contained an internal shorting bar that shorted the center conductor to the shell with no mating connector installed. In use, it was to short out the connecting cable so that any static on the line would be discharged before opening up the BNC connector to the internals of the TDR. Often, this shorting bar would break off, rendering the connector unable to discharge a cable to be connected. Replacing this BNC connector (or any front-panel component, for that matter) is a laborious process involving resealing the front panel for waterproofing. The original 1502 and 1503 were the first Tektronix instruments to be fully waterproof (with the X-Y Module installed) such that it could actually be operated while submerged to a shallow depth. The front panel sealing is a very involved process utilizing several different silicone (grease and RTV) products to do the job. Tektronix produced a separate | MOHR Test and Measurement manufactures a direct replacement to the 1502B and 1502C using an updated version of the same pulser/sampler ''[http://www.mohr-engineering.com/ct100 CT100B TDR Cable Analyzer]''. | ||
There appears to have been an optional "static suppressor" in a BNC M-F package, Tek [[011-0132-00]], used to protect the sampler and TD. It's pretty obscure. The BNC connector on later 1502s contained an internal shorting bar that shorted the center conductor to the shell with no mating connector installed. In use, it was to short out the connecting cable so that any static on the line would be discharged before opening up the BNC connector to the internals of the TDR. Often, this shorting bar would break off, rendering the connector unable to discharge a cable to be connected. Replacing this BNC connector (or any front-panel component, for that matter) is a laborious process involving resealing the front panel for waterproofing. The original 1502 and 1503 were the first Tektronix instruments to be fully waterproof (with the X-Y Module installed) such that it could actually be operated while submerged to a shallow depth. The front panel sealing is a very involved process utilizing several different silicone (grease and RTV) products to do the job. Tektronix produced a separate instruction manual specifically for waterproofing details of the 1500-series. | |||
The other common failure is the battery. The power supply was designed to protect both the instrument | The other common failure is the battery. The power supply was designed to protect both the instrument | ||