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647: Difference between revisions
added some circuit descriptions
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the plug-ins drive the deflection plates directly. The 647A followed the Type 647, which is similar | the plug-ins drive the deflection plates directly. The 647A followed the Type 647, which is similar | ||
but has 50MHz bandwidth. There is also an RM647A. | but has 50MHz bandwidth. There is also an RM647A. | ||
The vertical amplifier contained in the 647A indicator unit (mainframe) is made of | |||
NPN and PNP bipolar transistors. The output transistors, Q484 and Q494, | |||
are selected 2N3866 NPN transistors. | |||
The datasheet for the 2N3866 lists Ft as 800MHz and specifies an absolute maximum value of Vceo | |||
of 30V. The quiescent value of Vce on Q484 and Q494 is about 30V. So it seems likely that the | |||
selection process for these transistors involved testing their performance at the high end | |||
of their specified voltage range, and probably beyond. | |||
The power supply of the 647A is all solid state, with a zener voltage reference and NPN pass transistors | |||
at the outputs. | |||
The horizontal amplifier in the 647A uses selected 2N3119 NPN bipolar transistors for the output. | |||
These are specified as having and Ft of 250MHz and a Vceo max of 80V. | |||
Is it the only scope to use those plug-ins? It is unusual to see only one scope in what appears to be the beginning of a series. Was it discontinued because of lack of demand? What replaced it? | Is it the only scope to use those plug-ins? It is unusual to see only one scope in what appears to be the beginning of a series. Was it discontinued because of lack of demand? What replaced it? | ||