nRF52840 Preview DK v0.9.x

RF measurements

The nRF52840 Preview DK board is equipped with a small size coaxial connector (J1) for conducted measurements of the RF signal.

The connector is of SWF type (Murata part no. MM8130-2600) with an internal switch. By default, when no cable is attached, the RF signal is routed to the on-board PCB trace antenna.

A test probe is available (Murata part no. MXHS83QE3000) with a standard SMA connection on the other end for connecting instruments (the test probe is not included with the kit). When connecting the test probe, the internal switch in the SWF connector will disconnect the PCB antenna and connect the RF signal from the nRF52840 SoC to the test probe.

Figure 1. Connecting a spectrum analyzer
A spectrum analyzer connected to J1 on the nRF52840 Preview Development Kit board.

The connector and test probe will add loss to the RF signal, which should be taken into account when measuring, see the table below.

Table 1. Typical loss in connector and test probe
Frequency (MHz) Loss (dB)
2440 1.0
4880 1.7
7320 2.6