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519: Difference between revisions
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CRT part number is 154-308. | CRT part number is 154-308. | ||
== | == 125 Ω Input Impedance == | ||
The input to the 519 has an impedance of | The input to the 519 has an impedance of 125 Ω. | ||
The input connector is a special 125-ohm | The input connector is a special 125-ohm [[GR-874 connector]] made by Tektronix | ||
[[GR-874 connector]] made by Tektronix | that is neither electrically nor mechanically compatible with the much more | ||
that is neither electrically nor mechanically compatible | common 50 Ω GR-874 connector. Tek made a resistive impedance matching | ||
with the much more common | adapter, the [[017-053]], which presents a 50 Ω input (but attenuates the signal). | ||
== Rigid Coax Delay Line == | == Rigid Coax Delay Line == | ||
To allow viewing of the leading edge of pulses, there is a | To allow viewing of the leading edge of pulses, there is a | ||
rigid coaxial | rigid coaxial 45 ns [[delay line]] between the input and the CRT. | ||
[[ | [[File:519delay.jpg|thumb]] | ||
Note that 45 nanoseconds is an unusually short delay. | Note that 45 nanoseconds is an unusually short delay. | ||
For comparison, the delay line in a [[547]] is | For comparison, the delay line in a [[547]] is 170 ns. | ||
Keeping the delay short minimizes degradation of fast pulses, | Keeping the delay short minimizes degradation of fast pulses, | ||
but it necessitates a trigger and sweep circuit with quick response. | but it necessitates a trigger and sweep circuit with quick response. | ||
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by forced air sent from a blower through a duct. | by forced air sent from a blower through a duct. | ||
The total accelerating voltage of the 519 is | The total accelerating voltage of the 519 is 24 kV. | ||
The 519 contains a calibration step generator that produces voltage steps with 100 picosecond rise time, and a rate generator that generates pulses with 500 ps | The 519 contains a calibration step generator that produces voltage steps with 100 picosecond | ||
rise time, and a rate generator that generates pulses with 500 ps rise times. The step generator | |||
utilizes a charged line which is discharged through a reed relay, while the rate generator uses | |||
a transistor in avalanche configuration. The reed relay in the step generator is tuned in part | |||
by listening to it. | |||
== Unusual Physical Construction == | == Unusual Physical Construction == | ||
The physical construction and styling of the 519 | The physical construction and styling of the 519 differs from that of the other Tek scopes of | ||
differs from that of the other Tek scopes of the same period. | the same period. There are multiple reasons for this. First, it has an unusually long CRT. | ||
There are multiple reasons for this. | Also, the large 125 Ω coaxial delay line (seen in the photo) had to fit inside the cabinet. | ||
First, it has an unusually long CRT. | |||
Also, the large | |||
delay line (seen in the photo) had to fit inside the cabinet. | |||
Finally, the 519 has an extra-large power transformer | Finally, the 519 has an extra-large power transformer and a large blower for the 4CX250 tube. | ||
and a large blower for the 4CX250 tube. | The mass of these extra components necessitated a larger, sturdier cabinet than, for example, the [[545]]. | ||
The mass of these extra components necessitated a | The sheet aluminum used in the case of the 519 is thicker than that of the other Tek scopes of the period. | ||
larger, sturdier cabinet than, for example, the [[545]]. | The 519 weighs 99 pounds and uses 650 watts. | ||
The sheet aluminum used in the case of the 519 is thicker | |||
than that of the other Tek scopes of the period. The 519 | |||
weighs 99 pounds and uses 650 watts. | |||
== Different CRT Bezels == | == Different CRT Bezels == | ||
The 519 came with two different bezels. | The 519 came with two different bezels. | ||
Pictured in Tek Catalog 20 through 26 is the early | Pictured in Tek Catalog 20 through 26 is the early version which was actually a camera mount designed to | ||
version which was actually a camera mount designed to | be compatible with the C19 camera. It had a unique removable part with a graticule that could be slid down | ||
be compatible with the C19 camera. It had a unique | such that it would not be in between the CRT beam and the camera lens. | ||
removable part with a graticule that could be slid down | Most of the non-used area of the CRT faceplate was covered by the black plastic material of the graticule cover. | ||
such that it would not be in between the CRT beam and the | This graticule cover was changed slightly as is shown in the pictures of the 519 in Tek Catalogs 27 and later. | ||
camera lens. Most of the non-used area of the CRT faceplate | It still was designed to mount the C19 camera. ''(For what reason was the bezel design changed?)'' | ||
was covered by the black plastic material of | |||
the graticule cover. This graticule cover was | |||
changed slightly as is shown in the pictures of the | |||
519 in Tek Catalogs 27 and later. It still was | |||
designed to mount the C19 | |||
camera. For what reason was | |||
the bezel design changed? | |||
The 519 is probably the only Tek scope to come standard with a | The 519 is probably the only Tek scope to come standard with a camera mount for a bezel. You had to buy camera | ||
camera mount for a bezel. You had to buy camera | |||
mounting frames as accessories for the other scopes. | mounting frames as accessories for the other scopes. | ||
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later period was Mark Balcom. | later period was Mark Balcom. | ||
The distributed deflection plate delay network had to be hand-trimmed, which was done | The distributed deflection plate delay network had to be hand-trimmed, which was done | ||
to putting it inside the CRT envelope. It is possible that this was done using a TDR. | |||
a TDR. | |||
== 519C: A 3 GHz Version of the 519 == | == 519C: A 3 GHz Version of the 519 == | ||
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The 519 came with a set of adapters performing various functions such as interfacing the | The 519 came with a set of adapters performing various functions such as interfacing the | ||
125 Ω input impedance of the 519 with the more common 50 Ω impedance of many cables | |||
and instruments. One example is the [[017-0019-00]]. | and instruments. One example is the [[017-0019-00]]. | ||