I recently purchased a Boonton 8210 modulation meter, and have two questions about its operation. At turn-on, the display shows "12.88" for a few seconds, then "CAL". Does any one know the reason for the "12.88" display? Also - this unit has Option S/3, which places 2 AAA batteries inside the unit, connected to the "digital/PS" board. The military tech manual mentions this option, but does not explain it. Any ideas?