Connectors

Tektronix equipment makes use of a wide variety of connectors. Most of the connectors were standard parts when the instruments were designed. Occasionally custom connectors were designed. What follows is a partial list of connectors used in Tektronix equipment.

BNC

BNC is the most common connector for measurement equipment up to 1GHz. It was patented in 1951 by Hazeltine Research, Inc. It is available in different impedances. 50-ohm is the most common. Tektronix gear transitioned from UHF connectors to BNC connectors in the early to mid-1960's. For some pieces of equipment, a conversion kit was available.

• BNC Connector Patent (PDF)

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  BNC Female

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  BNC Male

SMA

SMA type are coaxial 50 Ω connectors good to about 20 GHz. The male connectors have a protruding center pin and ground shroud that screws on. The female is threaded on the outside. (Note that in the "Reverse Polarity" or "RP-SMA" connectors found in WLAN equipment, the pin is swapped to the shell with the exterior thread.)

SMA are somewhat similar to UHF connectors, but much smaller - initial Tektronix literature^(Note1) calls them "3 mm connectors" - and with much tighter tolerances and better controlled impedance. SMA connnectors are used on the S-50, S-51, S-52, 7T11, S-4, S-6 and many later GHz-class instruments such as the SD-xx series sampling heads.

(1) See Service Scope No. 52, Oct 1968 p.16, Something New in Oscilloscope Connectors

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  SMA Male

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  SMA Female

SMB

SMB connectors are small snap-on RF connectors developed in the 1960's. They come in 50-ohm and 75-ohm variants. Their RF performance in somewhat inferior to SMA connectors, but they are more compact and have the convenience of being snap-on instead of having a screw-on grounding nut. They are used in 1960's sampling and pulse gear like the 1S1, 4S1, and 284. They are also used in later equipment like the DC5010 and the 7D15. In general, SMB connectors are more widely used inside of RF equipment (on module interconnects, for example) than on front panels where SMA is more frequently found.

• Tyco SMB Connector Brochure (PDF)

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  SMB Connector as Strobe Input to 4S1 Sampler

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  SMB Connector as Tripper Pulse Input to 284 Tunnel Diode

GR-874

The GR-874 is a hermaphroditic (asexual) RF connector developed by General Radio in the late 1940's. They are typically for 50 Ω impedance, but versions for 75 Ω and 125 Ω were available using the same ground shield and housing, but different center pin geometry. Different versions of the connector have different maxiumum voltage ratings; 1000 V is typical. There are locking and non-locking versions.

GR-874 connectors are carefully engineered to keep a constant impedance throughout the signal path, by varying connector diameters between free-air and dielectrically supported sections. These connectors therefore exhibit very little reflection and are well suited for gigahertz and pulse applications.

The Tektronix 519 uses a 125 Ω GR-874 connector which has the same ground housing as the 50 Ω variant, but has a center pin that is thinner and shaped differently.

The regular 50 Ω version is used in the 1S1, 1S2, 3S1, 3S7, 3T7, 4S1, 4S2, 5T1, 5T1A, 5T3, 7M11, N, S-1, S-2, 106, 109, 110, 113, 280, 281, 282, and 282.

By the 1970s, GR-874 connectors were being supplanted by SMA connectors in test equipment, see e.g. the progression from the S-1 to the S-4 sampling heads.

Links

• 017-053 adapter
• GR-874 Section of 1973 General Radio Catalog (PDF)
• US Patent #2548457, Coaxial connector for high-frequency transmission lines. Filed 10 Jan 1947, granted 10 Apr 1951.

Pictures

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  50 Ω GR-874 connector

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  125 Ω GR-874 connector

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  Two 75 Ω and one 50 Ω GR-874 connectors

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  An assortment of GR-874 connectors and adapters

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  GR-874 50 Ω Terminator

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  7M11 delay line front panel with four GR-874 connectors

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  GR-874 connector on S-1 sampling head

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  Patent drawings from US2548457

Gremar

Gremar made many different connectors, but Tek scopes seem to use only of one of their connector systems. So in the context of Tek scopes, "Gremar connector" refers to that system. It is used in the 661 and 568 for trigger signals that are passed through the mainframe and into the plug-ins. It is a self-centering slide-in coaxial connector.

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Peltola

schematic drawing of Peltola connector components

The Peltola coaxial connector was developed by Ron Peltola at Tektronix for in-house use. These connectors are used extensively inside 7000-series scopes for all coaxial inter-board signal wiring and plug-ins as well as in some other instruments of the era.

According to the Tektronix website,

The Male coaxial connector consists of the RG-174 coax center conductor as the male pin, with the braided shield pressed between two eyelets, part number 210-0775-00 (smaller one) and part number 210-0774-00 (larger one). The outer eyelet is then "dimpled" to secure the eyelet-shield-eyelet combination.

The Female (circuit board mounted) connector consists of 2 pieces. In the center is the socket pin connector, part number 136-0252-07 and the connector recepticle (with 3 circuit board mounting tabs), part number 131-1003-00.

The tool used to swedge the two pieces of the Peltola together was custom-made, tool-by-tool in the Tek machine shop. They began with an inexpensive, common parallel-jaw fish cleaning pliers. The two opposing jaws were replaced by a new set, the end of each machined with a "mouse hole", one the width of the outside diameter of the larger eyelet, the other the width of the outside diameter of the cable. The smaller eyelet was placed over the end of the stripped cable and the braid spread out over the outside and trimmed off. Then the larger eyelet was positioned over the end of the smaller one, the tool carefully put into place, and the handles squeezed to press the eyelets together with the braid trapped between. That was all. There was no further dimpling step.

The Peltola shares simplicity and economy with the RCA phono connector common on stereo systems and the "F" connector, commonly used for television antenna connections. It's certain that the Peltola wins as the cheapest, simplest and highest-performance of the three.

(See also US Patent 3742425.)

Note that the shield may be at a non-ground potential. For example, the two connections between the interface board & readout board on the 7834 have their shields connected to the +15 V rail.

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  Mated connectors

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  Socket

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  Side view

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  Tip

UHF

The UHF connector is an early coaxial connector, basically a banana connector with a screw-on shield. The male is often called a PL-259, and the female is often called an SO-239.

Although it is called a "UHF" connector, the connector's construction does does not provide a controlled impedance that matches the impedance of the cables it is typically used with. Manufacturers usually specify this connector as suitable for use up to 200 or 300 MHz only.

The design has been used since the 1930's, and it is used on many pieces of early Tektronix gear, initially having the advantage that 4 mm (banana) plugs as used on earlier equipment could be inserted directly.

Like other test equipment manufacturers, Tektronix moved away from UHF connectors in the mid-1960s Tek provided kits that allowed owners or field technicians to convert instruments from UHF connectors to BNC connectors, which are smaller, quicker to attach and remove, and have better high-frequency characteristics (controlled impedance).

Contemporary use of UHF connectors is limited mostly to ham radio gear.

The UHF connector is used in the 511, 512, 513, 514, 515, 516, 517, 524, 525, 526, 531, 533, 535, 541, 543, 545, 551, 555, 575, 127, 1121, A, B, C, D, G, H, K, L, R, S, T, Z, 2A60, 60, 63, 72, 75, 104, 105, 107, 013-045, 013-045, 013-001-00, and 360.

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  The 013-045 has one male UHF connector and two female UHF connectors.

Banana

According to Wikipedia, the banana connector was invented in 1924 by Richard Hirschmann. The male (plug) is a 4mm shaft that has a springy shroud so it fits snugly in the female (socket), which is a 4mm hole. In American equipment, when banana plugs are used in pairs (e.g., power and ground), it is customary to place the two banana connectors 3/4" apart. Although the 3/4" spacing is a de facto standard in America, it is problematic in Europe, where a 3/4" double banana plug can easily be inserted into a wall (mains) power receptacle by accident.

N

The N connector is a threaded, weatherproof, medium-size RF connector used to join coaxial cables. It was invented in the 1940s by Paul Neill of Bell Labs, after whom the initial was chosen (although it is often claimed incorrectly that "N" is for "Navy").

The initial design was a 50 Ω connector for military systems operating below 4 GHz. In the 1960s, improvements pushed performance to 12 GHz and later to 18 GHz. 75 Ω variants exist (using a smaller center conductor diameter) but are rare (e.g. on some spectrum analyzers) and not compatible with 50 Ω connectors.

The N connector is seen as the input connector for Tektronix spectrum analyzers 1L20, 1L30, 1L40, and 492, the output on the 108 pulse generator, and others.

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BSM

Several Tektronix products use BSM connectors, such as the 7T11, 11B2, 3S2, S-50. S-51, and S-52. These look like minature BNC connectors. They are much less common than BNC connectors. There are two-lug variants and three-lug variants. Tektronix used the two-lug variant. They are also sometimes called MB connectors. The 067-0587-01 uses one for TRIG OUT. The 012-0127-00 converts from BSM to BNC.

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  BSM female on front lower right of 7T11

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  BSM to BNC adapters

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  BSM panel jack

IEC

IEC 320 (60320) C14 power inlet

IEC connectors are electrical power connectors specified by IEC standards. Mostly, the term is used for connectors in the IEC 320 standard issued in 1970 (since re-numbered to IEC 60320), and most often for the ubiquitous C13 / C14 type mains power inlet connector.

Lemo S-series

LEMO is a Swiss connector company founded in 1946. Tektronix used LEMO connectors to provide power to probes. 7000-series scopes have this connector.

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  Probe power connector on rear panel of 7104.

Octal

In some Tektronix equipment such as the 160 series, an octal connector is used. The plug resembles the bottom of a tube like a 6L6. The socket is an octal tube socket. The 160 power supply has octal sockets on the back, and octal cables bring the power to the modules such as the 161, 162, 163, and 360.

XLR

The XLR connector is most often used as a connector for microphone cables. It is used in the Tektronix Type E.

Amphenol 165-15

The Amphenol 165-15, which mates with a 165-14, is a MILSPEC connector with 9 #20 contacts and a current rating of 7.5A. It is used for the cable that connects the 175 to the 575.

• Amphenol 165 Data Sheet (PDF)

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  Rear Connector on 175

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  Rear Connector on 575

GPIB

GPIB connector on back of a Tektronix TDS210 scope

GPIB aka IEEE-488 uses a 24-pin Amphenol-designed micro ribbon connector. Micro ribbon connectors have a D-shaped metal shell, but are larger than D-subminiature connectors. They are sometimes called "Centronics connectors" after the 36-pin micro ribbon connector that Centronics used for their printers.