Collins 233D-3 Autotune Transmitter

[K5UJ]

This beast deserves to be fed the proper AC power and run just like it did when new, not 'restored' as a dummy.

I agree.  Some of the hams who are in the manufacturer fanatic clubs (Ten Tec, Drake, Collins come to mind) seem to prefer putting a rig up on an altar and worshiping it rather than operate it. 

that was a good story Slab.

[Steve - K4HX]

It's just as likely big rigs like that will sell for less than smaller rigs given that the market is so much smaller. The number of people willing or able to deal with the size and power   is small compared to those who can deal with a single cabinet sized typical 1 kW BC box.

[Todd, KA1KAQ]

compared to those who can deal with a single cabinet sized typical 1 kW BC box.

Which is, in itself, a very small slice. I doubt that price/value/originality are terribly important to the guys who hunt, haul, and operate the monster transmitters. No one on the other end can see what you're running, and plenty of guys running Flex/SDR rigs into big amps sound just as good as a big plate modulated rig. It's a labor or love and sometimes adventure more than anything else. Not for the ego-centered types as few will be impressed and far more will think you're crazy.

[Mike/W8BAC]

It's a labor or love and sometimes adventure more than anything else. Not for the ego-centered types as few will be impressed and far more will think you're crazy.

Well put Todd! It is a labor of love. That group in Cedar Rapids have that same ethic. The 233D-3 will be well cared for and will be back on the air soon. They don't build hanger queens.

Mike

[w0nkn]

An update on the Collins 233D-3:  The transmitter is currently in the old Comm Central equipment room in Cedar Rapids and several of us Collins oldtimers (along with a few Rockwell Collins employees) are attempting to revive it. 

The Rockwell Collins Museum web site has a section on the project that includes a blog based on my ramblings related to the project.  We have torn everything down and have had three of the chrome plated chassis replated and are in the process of gradually bringing everything up.  The filament circuits, bias supply, audio power supply and low voltage supply all appear to be working properly.  We are starting to "condition" the 872As in the high voltage system and expect to have that system working by the end of the month.  We hope to have the restoration work complete on the exciter (push-pull 813s) done by June and should be able to start RF tests then. 

The transmitter uses 450TLs in both the modulator and the finals.  The TDH-2 (1943) and similar age 231D transmitters used 750TLs in the finals, so we are trying to determine if any of the very early 231Ds had 450TLs in the final.

We have found very little in the Collins archives related to the 233D-3.  We expect it was special for Western Airlines. 

73
Jim w0nkn

[Todd, KA1KAQ]

That's excellent news Jim, thank you for the update. It's odd that you've had trouble locating infor about it in the archives there. It must have seen very limited/specialized use. I've seen more common military versions, but never that particular type.

It sounds like your HV supply is okay and you're just getting the mercury vaporized again in the tubes? If that's the case and the only hold up, you probably know that you can drop in 4B32 xenon replacements for testing etc in the meantime. They require no conditioning or extended warm up time, and are free of the arc-over issues the 872s display as they age.

Keep us posted, maybe include some photos as you move forward. We'd enjoy seeing it come back to life.