Hi,
The vintage Fluke PM6685 frequency counter allows an optional GPIB interface card (option PM9626) to be added. The EPROM on the card should have a firmware version matching that of the main board. The one I have is running on v1.05B, but I have not been able to find a corresponding B-version firmware for the PM9626 GPIB card. Fluke opened two support tickets, but I don't think they will be searching their attics for this. Maybe someone here on the forum with this instrument is able to read the EPROM content and send an image file? Any firmware file for the PM6685 or PM9626 would be highly appreciated.
Best regards,
Radko