7844: Difference between revisions

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{{Spec | Z axis input | 2 V<sub>p-p</sub> for full intensity range (positive decreases), input impedance 500 Ω, rise time 15 ns, max. 1 MHz }}

{{Spec | CRT | P-31 or P-11 (Opt. 78) ~~phosphor~~, acceleration 24 kV (-3/+21) }}

{{Spec | CRT | [[154-0713-00]] with P-31 phosphor, or [[154-0713-04]] with P-11 phosphor (Opt. 78), acceleration 24 kV (-3/+21) }}

{{Spec | Calibrator | 4 mV, 40 mV, 400 mV or 4 V into >100 kΩ, 0.4 mV, 4 mV, 40 mV or 400 mV into 50 Ω; 1 kHz }}

{{Spec | Power | 90-132 V or 180-264 V, 48 to 440 Hz, max. 235 W }}

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The 7844's CRT has [[distributed vertical deflection plates]]. It uses a number of custom ICs, such as [[155-0065-00]] and [[155-0059-00]] in the vertical amplifiers, [[155-0095-00]] in the vertical interface, [[155-0078-00]] in the trigger selector, and [[155-0022-00]] in the horizontal interface. The horizontal and Z axis amplifiers are discrete.

The 7844 is more complex than all other 7000 mainframes because vertical and horizontal amplifiers as well as the Z axis control boards exist twice, and there is an extra switching logic board. As a consequence, verifying correct operation requires testing many possible combinations of settings – for example, a defect on the vertical switching board could cause a problem only in the case of both beam 1 and 2 using horizontal bay B, but not if beam 1 used A and beam 2 used B.

The 7844 is more complex than all other 7000 mainframes except the [[7854]] because vertical and horizontal amplifiers as well as the Z axis control boards exist twice, and there is an extra switching logic board. As a consequence, verifying correct operation requires testing many possible combinations of settings – for example, a defect on the vertical switching board could cause a problem only in the case of both beam 1 and 2 using horizontal bay B, but not if beam 1 used A and beam 2 used B.

Moreover, calibration and adjustment is significantly more work than in a single-beam scope, e.g. CRT geometry trimpots need to be adjusted for matching both beams, not only for best geometry, and these adjustments slightly ~~interact~~.

Moreover, calibration and adjustment is significantly more work than in a single-beam scope, e.g. CRT geometry trimpots need to be adjusted for matching both beams, not only for best geometry, and these adjustments even interact slightly.

The power supply is a resonant switch-mode inverter with linear post-regulation, similar to the one in the [[7904]]. It uses the [[155-0067-02]] controller. Despite having an SMPS, the 7844 is fairly heavy behause of the duplicate internal components, especially the second vertical delay line. The delay lines need extra space and are located vertically to the right of the CRT instead of below the CRT as in other 7xx4s.

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* [http://www.firstpr.com.au/tequip/R7844/ R7844 page with frequency response measurements]

* [http://www.jvgavila.com/tek7844.htm Tek R7844 page @ EB5AGV], lots of internal photos

==Prices==

{| class="wikitable"

@@ Line 25: / Line 25: @@
 {{Spec | Horizontal bandwidth | DC to at least 1 MHz }}
 {{Spec | Z axis input | 2 V<sub>p-p</sub> for full intensity range (positive decreases), input impedance 500 Ω, rise time 15  ns, max. 1 MHz }}
-{{Spec | CRT | P-31 or P-11 (Opt. 78) phosphor, acceleration 24 kV (-3/+21) }}
+{{Spec | CRT | [[154-0713-00]] with P-31 phosphor, or [[154-0713-04]] with P-11 phosphor (Opt. 78), acceleration 24 kV (-3/+21) }}
 {{Spec | Calibrator | 4 mV, 40 mV, 400 mV or 4 V into >100 kΩ, 0.4 mV, 4 mV, 40 mV or 400 mV into 50 Ω; 1 kHz }}
 {{Spec | Power | 90-132 V or 180-264 V, 48 to 440 Hz, max. 235 W }}
@@ Line 34: / Line 34: @@
 The 7844's CRT has [[distributed vertical deflection plates]].  It uses a number of custom ICs, such as [[155-0065-00]] and [[155-0059-00]] in the vertical amplifiers, [[155-0095-00]] in the vertical interface, [[155-0078-00]] in the  trigger selector, and [[155-0022-00]] in the horizontal interface. The horizontal and Z axis amplifiers are discrete.
-The 7844 is more complex than all other 7000 mainframes because vertical and horizontal amplifiers as well as the Z axis control boards exist twice, and there is an extra switching logic board.  As a consequence, verifying correct operation requires testing many possible combinations of settings – for example, a defect on the vertical switching board could cause a problem only in the case of both beam 1 and 2 using horizontal bay B, but not if beam 1 used A and beam 2 used B.
+The 7844 is more complex than all other 7000 mainframes except the [[7854]] because vertical and horizontal amplifiers as well as the Z axis control boards exist twice, and there is an extra switching logic board.  As a consequence, verifying correct operation requires testing many possible combinations of settings – for example, a defect on the vertical switching board could cause a problem only in the case of both beam 1 and 2 using horizontal bay B, but not if beam 1 used A and beam 2 used B.
-Moreover, calibration and adjustment is significantly more work than in a single-beam scope, e.g. CRT geometry trimpots need to be adjusted for matching both beams, not only for best geometry, and these adjustments slightly interact.
+Moreover, calibration and adjustment is significantly more work than in a single-beam scope, e.g. CRT geometry trimpots need to be adjusted for matching both beams, not only for best geometry, and these adjustments even interact slightly.
 The power supply is a resonant switch-mode inverter with linear post-regulation, similar to the one in the [[7904]].  It uses the [[155-0067-02]] controller.  Despite having an SMPS, the 7844 is fairly heavy behause of the duplicate internal components, especially the second vertical delay line.  The delay lines need extra space and are located vertically to the right of the CRT instead of below the CRT as in other 7xx4s.
@@ Line 47: / Line 47: @@
 * [http://www.firstpr.com.au/tequip/R7844/ R7844 page with frequency response measurements]
 * [http://www.jvgavila.com/tek7844.htm Tek R7844 page @ EB5AGV], lots of internal photos
 ==Prices==
 {| class="wikitable"

7844: Difference between revisions

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