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#1
07-20-2016, 11:53 PM
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Wayne, why does high-def Saticon sound like an oxymoron? Now back to our regular thread.
__________________
“Once you eliminate the impossible...whatever remains, no matter how improbable, must be the truth." Sherlock Holmes. 
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#2
07-21-2016, 10:35 AM
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Frankly, it's been quite a while since I got this camera working and I don't remember whether or not the spot was there from the beginning, but it sure has been there for several months now. I might suggest, that if any of you are in the Los Angeles area, you'd be welcome to come over and take a look. Just let me know and I'll send you directions, etc. Write to: ralphsargent@earthlink.net
(PS: I have noticed that a number of these tubes improve their quality of picture when they have been run daily (for several hours) over a period of days or weeks since their long hibernation!)
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#3
07-21-2016, 01:23 PM
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Quote:
 Actually, special models with extra-fine spot size. As a result, the expected life was considerably shorter than the standard-def ones. We ran our first set for much longer than the expected life and replaced them eventually just out of caution, but kept the original set as emergency spares. The replacement set cost $85,000. (The camera originally cost $800k, which represented Zenith fully funding the engineering charges. AT&T bought a second one.) They were straining to get sufficient bandwidth without excessive noise. BTS limited the bandwidth in their cameras to about 22 MHz, where something more like 33 MHz was needed for full resolution. We had to wide-band ours for the proposed 1280x720 progressive format, and then we had a huge shielding problem because the BTS cameras used a 27 MHz internal clock for the control system. Sony supplied the Saticons to BTS, but Sony had proprietary low-noise FETs for their cameras and insisted BTS remove them and use BTS preamps. The preamps were soldered directly to the front of the Saticon, so BTS had a critical desoldering and soldering job to avoid damage. And now back to the original thread again! I still wonder if the multiplier focus voltage isn't off towards one end.
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#4
07-22-2016, 12:49 PM
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Dave: You had the same idea I did. Yesterday I went through the complete dynode divider chain and here are the results I found:
Typical voltages suggested by the datasheet: Grid #1 and 1st dynode 300 vdc 2nd dynode 600 vdc 3rd dynode 800 vdc 4th dynode 1000 vdc 5th dynode 1200 vdc Anode Voltage 1250 vdc Voltages measured after changing a few off value resistors due to aging: Grid #1 and 1st dynode 68 vdc 2nd dynode 490 vdc 3rd dynode 613 vdc 4th dynode 987 vdc 5th dynode 1160 vdc Anode Voltage 1187 vdc Not bad, but not terrible either. Any other guesses or opinions? The white spot is still there!
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