Hello.
Just two thoughts...
1. The calibration is out of date. Probably the 87V is quite in spec...
- but you can't be sure without a new one.
2. The 87V from 2008 is sensible for GSM-Frequencies.
Look at Dave's Video-Blog #112:
Fluke fixed it in the middle of 2011. With a modified PCB.
Because that's a hardware- issue, there's no updating possible.
Look at Dave's Video-Blog #185:
Greetings,
Hartmut