Troubleshooting WWVB Antenna Hardware
To troubleshoot a condition causing a red Antenna status lamp, remove the antenna cable from the clock. With a DC voltmeter, measure the antenna voltage output from the NetClock/2. Place the positive lead on the BNC center and the negative lead on the shell. The voltage under this no-load condition is 10.7 VDC. If no or low voltage is present, the NetClock/2 has a failure; contact Spectracom tech support.
To test the antenna cable, temporarily place a BNC "T" connector onto the antenna cable. Reconnect the antenna to the clock and measure the antenna voltage using the "T" connector. Typical voltage is around 4 VDC. If the voltage falls to 0 VDC, a short exists. If the voltage remains at 10.7 VDC, an open exists. Check the coax, connectors and surge arrestor for failures.
If the antenna voltage measures within the comparator window of 2.0 to 8.0 VDC but the antenna lamp is still red, the comparator circuit has failed. This failure could be due to lightning damage; contact Spectracom tech support.
Also check the continuity of the cable disconnected from the Netclock/2 from center conductor to shield. The table shows the resistance values based on the specific antenna configuration.
| Device |
Typical Resistance Value |
| Model 8206 active loop by itself |
6 Mohms |
| Model 8206A active loop antenna by itself |
6 Mohms |
| Model 8207 preamp (output side) with Model 8219 antenna |
12.2 kohms |
| Model 8207 preamp by itself |
3 Mohms |
| Model 8219 passive antenna by itself |
6.7 kohms |