Collins Aerospace Museum

233D Transmitter Restoration Project

As we discussed last Wednesday, I think Mike’s suggestion about bypassing the suppressor grid divider network and putting a jumper from the tap for channel 4 directly to the tube pin would at least eliminate the switch as a potential issue. If that solves the oscillator problem, then we need to attempt to align the switch wafer until we get the proper position relative to the channel select switch.

It appears that the switch wafer that sends the channel select agreement signal is working because we always get reversal on the Autotune motor. Problem is that we can’t consistently select a channel as indicated by the exciter Autotunes. What I don’t know is whether we are having agreement between the dialed channel and the crystal select switch.

We are no longer getting A0 shutdown. It is necessary to put the switch on the power control panel to “Remote” and then put the mode switch on the tone control panel to local to make the shutdown work. Of course, if we are using the “snubber” to reduce the relay buzz from the big filament relay, we won’t get shut down at all. One of the problems is that I get Autotune rotation when a dial an “A” and I don’t that is proper.

One more problem that has just popped up: we are no longer getting HV when we select the tune position. We get full voltage when we select the operate position. Since we usually hear quite a bit of contactor noise when we select either level and we are not getting any in the Tune position, I’m assuming we have a loose connection somewhere. Not a real big problem, but as soon as we get RF, I’d really like to like to have 1KV on the 813 plates while we are tuning up rather the full 2 KV.

I may start coming in on additional days in next couple of weeks. I’m working through a fairly long list of honey-do’s that will likely grow, but hopefully will get cleared next week.