_After the repair of the low band (up to 2 GHz ) now I have a drop in power at 13.5 GHz .

From the block diagram attached inside the doubler block I can see just switches and the amp for the doubler .

Following the signal from the RF mother board I discover a signal named HAMPLIFY that toggle with HPASSTHRU in band 3 switching off the bypass .

If there are no amplifier in multiplier unit it is an HW SW FW error if there is an amplifier is an amplifier fault ..

If someone Knows the HP83651B can help me?

Thanks

Gianni