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HP 8761A SPDT RF SWITCH
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The HP 8761A SPDT RF Switch is a single-pole, double-throw coaxial switch with excellent electrical and mechanical characteristics for 50 ohm transmission systems operating from dc to 18 GHz. It features broadband operation, long life, low SWR, excellent repeatability, and magnetic latching solenoids. The 8761A cost $325 in 1990 and is still a current Keysight product.
Top view
Bottom view
October 2014
I bought these 2 8761A's to make a change-over system so I can switch between either a direct cable connection or via the DUT (Device Under Test).
Although they have a 12 to 15Vdc coil voltage, a special driver circuit is required.
November 2016
Downloaded the Keysight 8761A/B Microwave Switches Technical Overview, which provides details of the switches and the driver circuit. This requires a 7404 Inverter and a DS0026 Driver ICs.
January 2017
More investigation into a control circuit. The RF switches are 'break before make'. The DS0026 Driver is available, but a logic control circuit is only required if remote control from a TTL pulse or HP-IB is required. A simple momentary 12V is adequate to connect port C with port 1, with polarity reversed for port C to port 2. The switch solenoids have magnetic latching and are not designed to withstand continuous current.
I bought these 2 8761A's to make a change-over system so I can switch between either a direct cable connection or via the DUT (Device Under Test).
Although they have a 12 to 15Vdc coil voltage, a special driver circuit is required.
November 2016
Downloaded the Keysight 8761A/B Microwave Switches Technical Overview, which provides details of the switches and the driver circuit. This requires a 7404 Inverter and a DS0026 Driver ICs.
January 2017
More investigation into a control circuit. The RF switches are 'break before make'. The DS0026 Driver is available, but a logic control circuit is only required if remote control from a TTL pulse or HP-IB is required. A simple momentary 12V is adequate to connect port C with port 1, with polarity reversed for port C to port 2. The switch solenoids have magnetic latching and are not designed to withstand continuous current.
Azur SCU120 Switch Control Unit
A Switch Control Unit was built in a plastic box and for portability 2 x 9V Batteries were used as the power source. A 12V Regulator circuit drives the 8761A's. Two momentary action switches (DP3T) operate the 8761A's solenoids. The N-type connectors are good for a bandwidth of 18GHz approx. See also HP 33312B Coaxial Switch for operation to 2GHz.
Front and rear views of Azur SCU120 Switch Control Unit
This is a useful accessory. It can be used to: switch two inputs to one output; or switch one input to two outputs; or switch a device (attenuator, cable, filter, mixer, test item, etc.) in and out of circuit. This all saves time when making repeated measurements.