Two Questions:

The 3 V battery for the NVRAM in my Tek 494 spectrum analyzer is down to 2.62 V. I understand memory is safely preserved down to the 2 V level; but is there any way to predict how much time is left?

While the backup battery is mounted in the GPIB board, it also feeds power to the Memory board. In pulling out the Memory board I realize I lost the information stored in its NVRAMs. Does anyone know offhand just how stored parameters are allocated between NVRAMs on these two boards? I am experiencing a phase-lock problem at upper frequencies of the 1st LO, and assume I may have lost tracking information.

Bruce, KG6OJI

2.6V is getting low, so I'd replace the battery fairly soon, but it's not an emergency. An ordinary CR2032 or similar 3V battery and holder is fine as a replacement. No internal calibration data is stored in NVRAM, other than the basic user calibration constants (shift-CAL button) which are easy enough to restore.

I'd suggest going through the frequency control system calibration procedure in service volume 1, and see if that helps. Skip the steps involving the PLL module unless you have board extenders. Then, if the error still occurs, you may have to delve further into it.

-- john, KE5FX