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I know what the technical definition of a shunt is. However this is an HP inline device that they call a "tracking generator shunt (50 ohm output)" It is used and came with the 8556A low frequency RF module as an accessory.

I doubt it is a simple shunt. But I may be wrong. It is used with the tracking generator on the 8556A, which has a 600 ohm output impedance. When you connect the TG output to a 50 ohm input you are to use this shunt to properly match the two different impedances. They also specify and provide with the unit new a 600 ohm Feed Thru Termination and a 50 ohm Feed Thru Termination. But this device they refer to as a shunt with 50 ohm output.

I am thinking it is something like a 550 ohm resistor with a 50 ohm resistor in series. The 550 ohm resistor input would be connected to the output of the 600 ohm TG. The 550 to 50 ohm junction would be connected to the input of the 50 ohm load, and the remaining end of the 50 ohm resistor would be connected to coax shield ground. That configuration would show a 600 ohm impedance for the TG and 50 ohms to the load and technically still be considered a shunt.

I built such a device and used it for the performance test (Para 4-18) and got reading within specifications for the first 10 out of 12 measurements. The two that were outside of specifications were only outside by 0.278% and 0.827%. Which may be because my resistors were not precision enough (50.22 ohms and 552.58 ohms measured with Fluke 45). Ideal is a 11/1 ratio this is a 11.032/1 ratio so may be a contributing factor. Or it maybe that my design is not what HP used. All of this is measured between 1 KHz and 300 KHz with my outside the specifications measurements being at the 250 KHz and 300 KHz frequency.

These external accessories seem to always disappear and never go with the used units. I was hopping someone might be familiar with them and give me some specific information as to exactly how they are built. At these frequencies construction is not a problem.

Steve, KJ5RV

br4av01 wrote: