Collins Aerospace Museum

Jun-11 ···
233D Transmitter Restoration Project

We completed testing the HV rectifier system and filter networks today. While everything was out, I hooked up the modulation transformer and subjected the primary and secondary windings to full voltage. I couldn’t find any high impedance resistors that I thought would handle the voltage and power, so wired up three strings of 470K 2 watt CCs with 9 in each leg for a little over 4 megohm in each leg. I applied HV to the center tap of the primary and one side of the secondary and attached the strings on the other end of the secondary and the two plate terminals of the primary. Grounded the three strings to both the case of the transformer and the negative for the power supply. No major problems observed, so I think that means the mod transformer windings can stand the full plate voltage with no indications of shorted turns or winding to case low impedance’s.

Mike is getting the lugs we need to build the high voltage cabling system between the plate transformer and the HV rectifier chassis.

Next week, we’ll be restoring the power connections to the contactor and the racks, so we can continue testing. Jules has finished work on the Autotune motor so we will check that next. We will work on getting the HV filter networks installed and get the high voltage wiring replaced in the racks. Goal is to have everything installed in two weeks.

Kelly is getting all of the Western Airlines documentation digitized, so it should be available for anyone to review.

In the next couple of days, I’m going to pull together all the notes and punch lists and publish what I think we need to complete to make the transmitter operational. I would appreciate any suggestions regarding additional tasks I may be overlooking.