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The Set: Pete Deksnis's Site about the CT-100

Restoring a Vintage Color Television Set

THE SET

restoration log

3-15-00. Our immediate pursuit is the acquisition of mechanical drawings that detail the electron gun used in the 15GP22 tricolor picture tube. To that end, we are indeed fortunate -- the archives of the former RCA tube manufacturing plant at Harrison, NJ are being inspected on our behalf. However, the production tricolor CRTs were almost certainly all built at the Lancaster plant, so there's only guarded optimism that mechanical drawing will be found in the Harrison archives.

Part of the RCA cathode ray tube manufacturing operation does survive today in Lancaster as part of Burle Industries. We have also made preliminary contact with them. It's possible they hold the Lancaster archives. Our thanks to Peter Keller, author of "The Cathode-Ray Tube: Technology, History and Application" for his help in spawning the archival search.

3-18-00 Heard directly from a curator of Harrison archives who had the following unexpected and welcome non-CRT restoration information and story.


Hi - I'm reasonably friendly with Dave, who pointed out your CT-100 site, and Peter Keller, who asked me to check the RCA-Harrison records for 15GP22 drawings (sadly, but expectedly, there were none).

Anyway, let me offer the following re the two-letter date codes on tubes in your sets. For RCA renewal tubes, there was a date-of-shipment code reflecting when the tube was sent from the warehouse (*not* the time the tube was made at the factory). For yours, the codes were:
(6BQ7A) - LA: Sept. '58
(12BH7A and 6AU4) - ND: Apr. '63
(6BC7) - MF: Apr. '61

This, from the RCA-Harrison archive, as reprinted in "Tube Collector," April '99. Can't tell you anything about the GE or Sylvania date codes, however. The diversity of the RCA dates hints at a probably rich history of service calls on your set!

When I entered college in the late '50s, I lived in a dormitory having eight sub-houses, each with its own entertainment budget. One house had a CT-100. The legend had it that the set went to whichever house had enough money to get the set fixed after its latest failure.

Anyway, I enjoyed your site (altho not specifically a TV guy) and wish you success on the restoration! --Lud

4-5-00 Brief 15GP22-rebuild update: Spoke with Bruce three days ago. The electron gun removed from a dud is on its way to Frederick Glass. Object is to have them investigate the availability of an existing stem that might be an economical alternative to developing a new one, so that rebuild costs are held as low as practicable.

4-21-00 Here's the latest leeward tack in our 15GP22-rebuild voyage. I quote Bruce: "I continue to work toward getting a source for a suitable stem. Although things have moved slowly, it looks good that ETI [a Fredericks acquisition] will be able to produce the need stem. Though they have not located the mold for the stem, they are sure that they have in their inventory a mold that was once used for making stems used on the 15GP22 bulb. As I have explained earlier, they own the stem-making equipment purchased from RCA in the 50s. I talked to HB, a glass specialist who consults with ETI and who is in the plant a couple of times a month. He will look up our mold when he is there the next time."

4-22-00 Probably due to my building a 300-MHz AMD-based computer months ago (to replacing an aging 100-MHz Pentium), an interesting e-mail from Gary got misplaced, misdirected, or somehow overlooked. It seems in our quest for information and expertise, someone skilled in the science of glass technology was right in our backyard. Kind of an Acres of Diamonds thing. Anyway, here's an April 21 e-mail from Gary.

"To all in this group: We build vacuum tubes for a UV photocell application in high end flame detection systems. We have 3 skilled stem molding operators, three envelope sealing operators and three more tip off operators who can torch seal or electrically heat seal tubes which must be reliable for 25 years in harsh environments. I am staff engineer for this group.Given a little recognition and some resources, maybe we can help in this project. PS: I have two 15GP22's and one rebuilt chassis. Gary F.; Staff Engineer, Sensors; Detector Electronics Corp."

6-5-00 To all of you who follow this 15GP22 rebuild saga, rest assured that additional information will be posted as it becomes available. Thanks for checking in.

6-14-00 Another progress report and a BIG milestone. What you see is a stem, made an unknown number of years ago, but made specifically to rebuild the 15GP22! This single specimen reached Bruce today from Fredericks where it was found in a search initiated by Bruce in his quest for an economical rebuild protocol for the 15GP22. The stem was photographed and rushed off to John B. at Global, the gun rebuilder. It should arrive by this Monday, June 19. If Global determines that it can use this stem to rebuild the gun, one of Steve's duds will probably be the first in line to test the process. The completed gun assembly will be sent from Global to Hawkeye where the 15G' gets its rebuilt gun installed and the bottle evacuated and tested. And finally, Fredericks' people believe a few more existing stems can be found, but they can build as many as we need. The difference will be the conductor material. This specimen was made with nickel wire. New stems will have Sylvania #40 pins. So there may be an issue or two with the connector, but nothing critical. And so it goes...

Our sample has all 20 positions populated with wire leads. The two unused pins before and after pin 13 will have the leads cut back. Apparently all 15GP22's were manufactured this way. Some consideration is being given to manufacturing new stems without the four unused leads. This decision has yet to be made.

[When the run of new stems was manufactured in early 2003, they were made with all 20 leads.]

9-28-00 After a summer hiatus, the 15GP22 rebuild process is again under active development. There will be updates posted here very soon....

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(Updated June 5, 2005)