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Frequency Mixers - How not to overload

Jan 4th 2013, 21:53


Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
I have a TUF-3 frequency mixer from Mini Circuits. The data sheet can be found at

The data sheet says the LO input power to the mixer should be +7 dBm. So if I have built an LO, how do I know if the power it will transfer to the mixer is +7 dBm? I have an oscilloscope, so I can measure the voltage at the LO output, but without knowing the impedance of the LO port on the mixer, I can't convert this to a power level.

The data sheet for the mixer says nothing about impedance at the various ports, and I can only assume that it depends on the impedance present at the other ports. So, perhaps the underlying question is "how is the input impedance of the IF strip connected to the IF port reflected back through to the LO port and the RF port?"

The mixer data sheet also contains data on the VSWR at both the RF and LO ports at various frequencies, but without any information about impedance I am not sure how to interpret this.

Any help appreciated.

Jan 4th 2013, 23:12


Super Moderator

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0

Typically, if your LO will deliver +7 dBm to a 50 ohm load, it should work just fine.

Zack Lau W1VT
ARRL Senior Lab Engineer

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