7503
The Tektronix 7503 is a 90 MHz 7000-series mainframe with three module bays, introduced in 1970. It was effectively replaced by the larger-screen 7603 in 1972.
The 7503 project was managed by Phil Crosby, and was supposed to be a 7504 but with one fewer plug-in. The 7503 was Tek's first scope to use a harmonica connector for inter-board wiring. Prior to this, inter-board wiring had either mainly been point-to-point soldered. Other approaches were taken on certain instruments, for example the 7704, in which pins sticking out of the chassis mate with holes in the boards that receive the pins and make electrical contact.
Unlike later three-slot (7xx3) mainframes, the 7503 does supply the +5 V lamp rail, which helps with the contemporary 7A12 plug-in. It also features the 7000-series remote control connector at the rear of the unit.
Key Specifications
| Bandwidth | 90 MHz with 7A11, 7A16 (and faster plug-ins); 75 MHz with 7A12, 7A13, 7A14 |
|---|---|
| Fastest calibrated sweep | 5 ns/Div |
| CRT | T7500 (154-0608-xx), 18 kV total acceleration (+15/-2.96) |
| Vertical modes | Left / Alt / Add / Chop / Right |
| Trigger Source | Left / Vert Mode / Right |
| Calibrator | 4 mV to 40 V in five decade steps, 40 mA, 1 kHz ±0.5% |
| Outputs | Side panel: Vert signal, +Gate, +Sawtooth; At CRT: Camera power |
| Line Voltage | 90-110 V / 104-126 V / 112-136 V / 180-220 V / 208-252 V / 224-272 V, 50—440 Hz |
| Power | Max. 258 W |
| Weight | 21.3 kg / 47 lb (instrument only) |
| Rear connectors |
|
Internals
In addition to two custom Tek ICs, the 7503 uses CA3046 transistor arrays (156-0048-00) in eight places (five on the regulator board). The vertical and horizontal amplifiers are built using discrete transistors.
The 7503 has an X-Y delay compensation network that is activated when the H plugin is an amplifier or a timebase in amplifier mode (see 7000 Series plug-in interface). This network is switched in using a pair of 148-0034-00 miniature relays on the horizontal amplifier board.
Like other 75xx and 76xx mainframes and the 7504, the 7503 has a linear power supply, as opposed to the switchmode supplies used in the later 4-slot mainframes. In addition to the +5 V, ±15 V, ±50 V rails common to the 7000 series, internally (not on the plug-in slots) it has a +75 V output not found in later models, and a +150 V instead of the later +130 V.
The 7503 contains a mercury-based elapsed time meter on the rear of the main interface board.
Pictures
-
Front
-
Plug-in bay
-
Plug-in connectors missing sides
-
7503 backplane PCB mid-repair
-
Horizontal amp on top
-
Vertical amp on the side
-
Left view, delay cable, CRT
-
Left view, power supply
-
Right view, mains frequency transformer
-
Readout board
-
Right side connector panel
-
Rear
-
-
-
Custom ICs used in the 7503
| Page | Model | Part nos | Description | Designers | Used in |
|---|---|---|---|---|---|
| 155-0011-00 | M012 | 155-0011-00 | clock and chop blanking | Les Larson | 485 • 7313 • 7403N • R7403N • 7503 • 7504 • 7514 • 7603 • AN/USM-281C • 7613 • 7623 • 7623A • 7633 • 7704 • R7704 • 7704A • 7834 • 7844 • 7854 • 7904 • 7904A • R7903 • R7912 • 7912AD • 7912HB • 7934 • 7104 • R7103 • AN/USM-281C |
| 155-0022-00 | M036 | 155-0022-00 • 155-0022-01 | analog multiplexer | Gene Andrews | 147 • 148 • 149 • 335 • 468 • 1430 • 1441 • 1461 • 1900 • 1910 • 2220 • 2221 • 2230 • 5223 • 5403 • 5440 • 5441 • 5443 • 5444 • 5A38 • 7313 • 7403N • 7503 • 7504 • 7514 • 7603 • AN/USM-281C • 7613 • 7623 • 7623A • 7633 • 7704 • R7704 • 7704A • 7834 • 7844 • 7854 • R7912 • 7912AD • 7912HB • 7904 • R7903 • 7904A • 7934 • 7A12 • 7A18 • 7A18A • 7A18N • 7B52 • 7B53N • 7D10 • 7D11 • 7D12 • NT-7000 • P7001 |