The Agilent HP 5341A Frequency Counter performs exceptionally fast measurements of frequency up to 4.5GHz

Other Info:
Using a unique HP-designed microwave switchable filter, its automatic heterodyne measurement technique insures high tolerance of FM on the measured signal.
In the normal mode of operation, the Agilent HP 5341A will automatically measure and display the lowest CW signal within its sensitivity;
in the manual mode, the operator can choose to search within any of ten frequency bands which cover the counter's full range.
Type N & BNC connectors; ±1% accuracy; 50-ohms.