310

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The Tektronix 310 is a compact portable oscilloscope introduced in 1955. It was designed by Frank Hood and John Kobbe. It is a 4 MHz single-trace, single-timebase scope with a 3" (7.5 cm) round CRT.


The Hickok company produced a clone of the 310 under a US military contract as the AN/USM89B.

Key Specifications

Bandwidth 4 MHz (3.5 MHz below 0.1 V/Div, AC coupled)
Rise time 90 ns (100 ns below 0.1 V/Div, AC coupled)
Sweep 0.5 μs/Div to 0.2 s/Div 1–2–5
Deflection 10 mV/Div to 50 V/Div, 1–2–5 (below 0.1 V/Div only AC coupled)
Input impedance 1 MΩ // 40 pF
X input 1.5 V/Div, 500 kHz, 100 kΩ
Z input 20 Vp-p at rear "CRT Cathode" binding post
Calibrator 0.5 Vp-p to 100 Vp-p, 1–2–5; 1 kHz
Power 175 W

Internals

Cooling

The 310 is a tube scope and uses 175 watts, but it does not have a fan. It therefore tends to run hot, particularly when used in a hot environment with still air. It has a 165 °F (74 °C) thermal cutoff switch in series with the primary of the power transformer. For extended use in one place, a tilted fan base, the FB310 (part number 016-012) was available. The fan base blows air upward through the perforated bottom panel of the 310.

The 310 is hinged at the rear, allowing reasonably convenient access to the circuitry despite the fact that the components are packed more densely than in other Tektronix scopes of the era.

310A

A revised version, the 310A, was introduced in 1959. The 310 uses printed-circuit boards but the 310A returned to ceramic strip construction. P2 phosphor was standard. P1, P7 and P11 were also available.

Is this the only time that a Tek design was moved from PCB back to ceramic strip?

This is a nearly true pure vacuum-tube scope, but in the power supply there are some silicon rectifiers and in the circuit is one germanium point contact diode. It is sometimes very useful because it contains a 1 kHz calibrator output with up to 100V level combined with a step attenuator.

Early examples of the Tektronix Type 310A used commodity 3WPx CRTs. At some point in production, they switched to the Tek-made T3100 CRT, which is compatible with the 3WP2.

Unlike later Tek instruments, where the incremental model designated by an “A” suffix only occurred with a significant specification or performance enhancement, the original 310 and 310A were essentially identical. They even shared the same manual and schematics. The main difference was the wiring construction. needs to be checked - different tubes used according to the manuals

The original 310 pioneered the use of circuit board construction, rather than the trusted ceramic strip point to point wiring. The circuit boards were two sided, however plated through hole technology to interconnect the layers had not been invented yet. Rather, all of the holes for component mounting and interconnect contained a rivet which was expanded in a press before the components were installed in the board. The rivets themselves were not soldered to the copper foil traces, and relied on the pressure from the crimp to make contact. This proved to be extremely unreliable, with many intermittent connections resulting in high warranty- and after-warranty failure.

The 310A model essentially used the identical circuit design, but returned to the trusted ceramic strip construction method.

The 310A also replaced the selenium plate rectifiers in the power supply with silicon diodes. Tek offered a retrofit kit, to be installed in the service centers, to upgrade older scopes with selenium rectifiers.

During the lifespan of the 310, Tek evolved its color scheme. The original 310 scopes had a case painted with a blue metallic hammer tone color. Later units moved to the crinkled “Tek Blue” color still in use today.

The scope cabinet was hinged to allow it to be opened like a book and operated for access to the circuitry for service purposes. The 310 and 310A were convection cooled, and required free access to air through the cabinet vent holes to avoid overheating. It contained a thermal cut-out to protect it from damage if the supply of cooling air was inadequate. The scope has feet on the rear panel to allow it to be operated on the floor with the front panel facing up, but the manual warns against prolonged operation in this orientation. Shortly after introduction, Tek offered a Fan Base accessory, which the scope would sit on and provide forced air for better cooling. While the scope had universal primary wiring options, the fan base did not. Separate models were available for 115 VAC or 230 VAC operation.

Like most old Tektronix devices the mains transformer holds an indefinite(!) warranty, so hold an eye to that. The device goes away on ebay here often for 30€ to 60€.

Fun on

  • But its not quite clear what the "indefinite" means, live long for the device, the first owner, the company (Tek), the universe, or the transformer itself? ;-)

Fun off

Links

Pictures


Some Parts Used in the 310

Page Class Description Used in
12AT7 Vacuum Tube (Dual Triode) dual high-gain triode 161 180 310 310A 315 316 360 502 502A 512 513 513D 514 514AD 514D 516 524AD 529 RM529 544 546 547 556 3A2 3A75 1M1 A B C G H K L M N K R S Z
12AU7 Vacuum Tube (Dual Triode) dual medium-μ triode 122 160 161 162 181 190 310 316 317 502 502A 512 516 517 517A 526 535 536 545 545A 545B 547 549 555 575 581 581A 585 585A C D E N Q
12B4 Vacuum Tube (Triode) power triode 126 310 310A 316 317 502 502A 526 541 541A 535 535A 545 545A 546 547 549 551 555 513 581 581A 585 585A
3WP CRT series of flat-faced 3" mono-accelerator CRTs 315 310 360 Telequipment S31
5642 Vacuum Tube (Diode) directly-heated high-voltage rectifier 310 310A 316 317 360 453 502 502A 503 504 506 513 515 516 529 RM529 533 533A 535 536 543 543A 543B 545 545A 545B 547 551 555 556 567 575 581 581A 585 585A 647
6AL5 Vacuum Tube (Dual Diode) high-perveance dual diode 163 181 190 310 310A 315 316 317 502 502A 503 511 511A 512 516 517 517A 526 535 535A 545 545A 549 581 581A 585 585A 551 C T Telequipment S52
6AN8 Vacuum Tube (Triode/Pentode) triode-pentode combo 310 310A 316 317 360 502 502A 516 517 517A 526 575 N
6AQ5 Vacuum Tube (Pentode) beam pentode 310 310A 316 360 512 517 517A 536 575
6AU6 Vacuum Tube (Pentode) RF pentode 2A60 80 107 160 181 190 310 310A 316 317 360 502 502A 512 513 516 517 517A 526 529 RM529 531 531A 535 536 545 545A 546 547 549 555 575 581 581A 585 585A C CA Q
6BH6 Vacuum Tube (Pentode) pentode 162 310 310A 512 517 517A Nelson-Ross PSA-011
6BQ7A Vacuum Tube (Dual Triode) dual triode 107 163 310 316 360 181 315 524 531 532 535 536 541 545 T
6CL6 Vacuum Tube (Pentode) miniature power pentode 132 310 310A 316 317 515 524 525 531 535 535A 545 545A 545B 549 581 581A 585 585A 3A74
6U8 Vacuum Tube (Triode/Pentode) triode-pentode combo 130 160 163 310 315 316 535 545 T
T3100 CRT 3" CRT 310 310A 315 360


Some Parts Used in the 310A

Page Class Description Used in
12AT7 Vacuum Tube (Dual Triode) dual high-gain triode 161 180 310 310A 315 316 360 502 502A 512 513 513D 514 514AD 514D 516 524AD 529 RM529 544 546 547 556 3A2 3A75 1M1 A B C G H K L M N K R S Z
12B4 Vacuum Tube (Triode) power triode 126 310 310A 316 317 502 502A 526 541 541A 535 535A 545 545A 546 547 549 551 555 513 581 581A 585 585A
5642 Vacuum Tube (Diode) directly-heated high-voltage rectifier 310 310A 316 317 360 453 502 502A 503 504 506 513 515 516 529 RM529 533 533A 535 536 543 543A 543B 545 545A 545B 547 551 555 556 567 575 581 581A 585 585A 647
6AL5 Vacuum Tube (Dual Diode) high-perveance dual diode 163 181 190 310 310A 315 316 317 502 502A 503 511 511A 512 516 517 517A 526 535 535A 545 545A 549 581 581A 585 585A 551 C T Telequipment S52
6AN8 Vacuum Tube (Triode/Pentode) triode-pentode combo 310 310A 316 317 360 502 502A 516 517 517A 526 575 N
6AQ5 Vacuum Tube (Pentode) beam pentode 310 310A 316 360 512 517 517A 536 575
6AU6 Vacuum Tube (Pentode) RF pentode 2A60 80 107 160 181 190 310 310A 316 317 360 502 502A 512 513 516 517 517A 526 529 RM529 531 531A 535 536 545 545A 546 547 549 555 575 581 581A 585 585A C CA Q
6BH6 Vacuum Tube (Pentode) pentode 162 310 310A 512 517 517A Nelson-Ross PSA-011
6CL6 Vacuum Tube (Pentode) miniature power pentode 132 310 310A 316 317 515 524 525 531 535 535A 545 545A 545B 549 581 581A 585 585A 3A74
6DJ8 Vacuum Tube (Dual Triode) dual triode 80 132 161 310A 316 317 3A75 502 502A 503 504 515 516 519 526 529 RM529 533 535 536 543 544 545 545A 545B 546 547 549 555 556 565 581 581A 585 585A 661 2A60 63 2A63 3A7 3A8 1121 1A4 67 81 82 86 3B1 3B4 1S1 B O W Z Telequipment S32A Telequipment D52 Telequipment TD51 Telequipment S52 Telequipment S51 Telequipment Type A
T3100 CRT 3" CRT 310 310A 315 360