A couple of Sunday morning observations.
It appears these receiver chassis were inspected at a standard inspection station that used a steel stamp punch to verify the inspection. I have found this 5/16 inch stamp on the outer left and right chassis side panels on both the main set receiver and the remote receiver. these two units are roughly 2,000 apart by serial number in Marconi's 1944 production.
The other interesting discovery relates to the Crystal Calibrator chassis in the upper left corner of the receiver. If you check back at the photo in Post #4, you will see a large daub of blue paint on the calibrator chassis at the left end of it. I found the remains of a similar daub on the Remote Receiver calibrator chassis.
This mark was applied at the factory to denote that all the valves in the calibrator have been 'aged'. That means they have been run for 12 hours to ensure the electrons will feel right at home in the valves when they are put to work. In addition, the receiver manual notes that Marconi has aged all essential and spare calibrator valves issued with the set. These valves have also been marked with a blue dot of paint on the end of the locating pin.
Whenever a valve has been replaced in the calibrator, the calibration test needs to be performed. With an aged replacement valve, this test can be done straight away. If the valve has not been aged, the calibrator needs to be run for 12 hours before the test can be performed.
David
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