Electronics > Repair
E4407B Tracking Generator Repair
smgvbest:
I installed a tracking generator I got off ebay into my repaired E4407B and after making the LO and 600Mhz Reference Cables fire it up and found it does have an issue.
When it fire up and enabled the TG I received a Source TG Unlevel, i double checked my cabled and snugged up the LO cable at the LOIS side and the Source TG Unlevel went away and was replaced with a Source Unlevel. Doing some checking at 0.5DdB intervals I checked from 4dB to -66dB and got the table below.
Interesting that at a fairly regular interval it goes from Source Unlevel to No Error (Pass in the table)
--- Code: ---Start End Range Status
3.0 -6.5 -9.5 Source Unlevel
-7.0 -9.5 -2.5 Pass
-10.0 -14.5 -4.5 Source Unlevel
-15.0 -17.5 -2.5 Pass
-18.0 -22.0 -4.0 Source Unlevel
-22.5 -25.5 -3.0 Pass
-26.0 -29.5 -3.5 Source Unlevel
-30.0 -33.5 -3.5 Pass
-34.0 -37.5 -3.5 Source Unlevel
-38.0 -41.5 -3.5 Pass
-42.0 -45.5 -3.5 Source Unlevel
-46.0 -49.5 -3.5 Pass
-50.0 -53.5 -3.5 Source Unlevel
-54.0 -57.5 -3.5 Pass
-58.0 -61.0 -3.0 Source Unlevel
-61.5 -66.0 -4.5 Pass
--- End code ---
At the suggestion of Jürgen over on the HP-Agilent-Keysight group.io group I disconnected the RF out to the attenuator and ran same test. I got same result
the idea being is the issue with the LO on the control board or in the BITG which is not documented.
So I'm going to basics and starting with a visual inspection then checking the LO Path on the control board.
So what follows is a boat load of images of the control board. after those images I will continue posting on testing
smgvbest:
This is the top side of the control board E4403-60004
smgvbest:
rest of top board
smgvbest:
Board side of Control Board
smgvbest:
Close up of the LO Amps and Pin Modulator sections
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