The HX2410 was originally a oversized black box on a Holzworth test bench. It was designed and used by Holzworth engineering to observe the true channel-to-channel phase coherency performance (relative ch-ch stability) of the HS9000 Series Multi-Channel Synthesizer products. At one point, a customer phoned into to the Holzworth support line to discuss his observation that although the channel to channel stability was very good, it was not as good as specified. What is often overlooked is that a low frequency sinusoidal trigger signal has a slow slew rate which induces jitter into the measurement.