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Wierd Spike 1 with VMC and ELO

Question asked by neilbaliga on Sep 12, 2013
Using Agilent 5224 FW Rev A.09.85.06
Frequency translated device using ELO in a VMC channel

Issue 1: Swept POWER Test

A spike ALWAYS occurs at the FIRST point after the second division in the X scale
The spike occurs regardless of the power range swept : it is always the first point after the second division
The spike is on the order of 1dB
The spike is a SINGLE point spike at the EXACT same location regardless of how many points are swept or how many dB is swept
There is also a corresponding phase drop in VC21 phase at the same point
The spike is present in the R1 and VC21, but NOT in the B channel measurement from the DUT
The spike DOES NOT occur when I hot switch the DUT test configuration to an LO locked configuration (leaving ELO on and everything the SAME on the PNA)
The spike DOES NOT occur in the LO locked configuration with ELO off

The spike IS NOT at the ELO tuning point. 
(We are also experiencing another phenomenon AT the ELO tuning point I will create a new thread for that)
I have moved the tuning point closer/further and it makes no difference. 
The spike is always at EXACTLY the same point (first point after the second X axis division)

If I add a measurement dwell time of at least 20 mSec, the spike appears to go away in VC21 Mag, but not in VC21 Phase

I looked through the release notes and did not find anything to indicate this was a known problem or has been fixed

Please advise....