233D Transmitter Restoration Project
I misspoke about the crystal holders: we have four installed. They are type 249 by B.L. Davis, Seattle. See the attached image. The stamped frequencies are 1500.5, 2327.25, 3309.75 and 5033. I expect these are submultiples of frequencies used by airlines in the HF AM days. I havenít been able to find much on the web regarding airline HF ops during the early Ď50s but perhaps someone will have better info. The holders are apparently capable of holding two crystals although our 4 have only one in each holder. The compression spring is much larger than I would have expected. It would be possible to install modern crystals in the holders if it becomes problematic to get exact replacements.
Jules came by yesterday and reviewed some of the Autotune circuits.
Still struggling with the power contactor assembly. Jules noticed that the test mode contactor has some indications of extreme heat on the coil so we need to investigate that. I did remove the cover over the contactor contacts (disregarding the Allen Bradley dire warnings about not attempting to clean or file the contacts). The test mode contactor has some pitting on one of the contact pairs continuity appears good, although I noticed that manually closing the switch did not make contact, so it is likely that coil power will have to be applied; I think there are adjustments, if necessary. Unable to determine why one of the phases that supplies the racks is not wired as shown on the schematic. The cable harness doesnít appear to have any evidence of rewiring, so we need to investigate before we attempt to apply rack power. Would like to make this a priority for next Wednesday, so would appreciate some help then.
Electricians are planning to install some heavy wiring over the July 4th holiday over the Byrd transmitter, so they wanted to know if we would agree to move it. Lawrence suggested we move it into the 233D/Starship room. The electricians said the floor should be able to handle it since the HF-8022 were likely heavier so they moved it and it looks pretty nice behind glass now. I moved the coat rack down the hall and plugged it back in so it looks good with the lights off. If we put an HF-80 rack on the south side of the room, it could be a nice exhibit of early, old and more recent technology.
Electricians will also check to determine why the overhead lights over the hallway exhibit and the overheads in the room are not coming on. Appears that the feed to the sliders is dead, so they will investigate. The directed light from both of those strings would really high light both the hallway exhibit and the big transmitter; and we donít need a work order to get them fixed. I vaguely recall the hallway lights being on as well as those in the radio area when Comm Central was still there.
Iím taking a break after next Wednesday until the week of June 17th. We may be getting the chassis back from the Quality Plating that week. If anyone is coming back from the Chicago area, it would be great if they could be picked up. Otherwise, I think it would be better to have them shipped than having another 230 mile round trip. Quality thinks the work will be done before they shut down for the last week in June; if not they are sure to have them complete by July 8.
Jim Stitzinger will be in town this evening with his TSC-60 shelter, so will happy to demo it to anyone who is interested. He is getting copies done at FedEx, so will either be there (in the Best Buy parking lot) or in one of the RC parking lots. He expects to be in Cedar Rapids around 5 PM. If anyone is interested, call me around that time to determine more details. Jim will consider staying around Friday morning for a while, if anyone is interested, but would really like to get back to California, since he has been gone for sometime.
| May 30, 2013