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Old 03-28-2008, 11:33 AM
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Tomcomm Tomcomm is offline
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Join Date: Nov 2007
Location: Santa Ynez, CA
Posts: 353
21CT55 Progress with Background

Thanks for your response to my 21CT55 postings. Seems the screen display keeps getting more impressive as I learn thru trial and error how to get it setup properly. It operates as a video monitor with the imbedded IC video op-amp I installed that presently allows two matched switched inputs to the CTC2B's 1st video amp grid. This 3vpp level matches the original RCA designed diode video detector output. Those engineers did everything right on these first CTVs in 1953. I went to work for RCA in west Los Angeles in 1953 straight out of high school as a lab tech. Made engineer in 1956. I did defense stuff, no interest in color TV until my Dad won a new '56 CTC4 in a raffle. I stayed up the first night till 3am trying to "improve the convergence". Not a good start in color TV but I was hooked on the technology.

When I bought my 21CT55 for $50 in '64, I brought it into the house after I got it working and ran it along side my Dad's old CTC4 he left me. Both had 21FBP22s so it was a good comparison of narrow bw color R-Y B-Y vs. full bw color I Q. The extension of full color into fine detail on the CTC2B was startling! Color persisted in fireworks until extinction which I never saw before. The CTC4 fireworks turned into white long before extinction. The CTC2B carried full color way into the shadows, the CTC4 went gray to black. I kept the CTC4 in the house for the kids but brought the CTC2B back to the garage workshop for further study. Ease of working on the chassis and CRT "forced" me to destroy the cabinet and configure the remains into the vertical chassis configuration I am blessed with today. That’s alright with me. I respect the original CTV restores but that’s not my thing.

Since ota NTSC is headed for oblivion in Feb '09, I see little incentive to go thru the futile exercise of getting the chassis's tuner, video and sound IF sections operational. I intend to open the heater string to all involved tubes and just let them hibernate. Probably lose about 100w off the present > .5kw it draws from the "mains". I've got plenty of quality NTSC composite video sources to keep the "old guy" demonstrational indefinitely. In addition to the C-Band Big Dish analog and 4DTV digital I've got a Koss DVD player (don't laugh) and a Magnavox Laser Disk player with about 20 disks including most of the Star Wars transfers. And of course, I expect to get my ASTC tuner coupons any day now (sic) for ota digital reception. I'm sure I'll be disappointed with the PQ of network SDTV, but then its free.

Big problem now is the poor quality of off-screen digital camera images. I get really awesome displays on the 21FBP22A with vibrant, accurate colors. Having the CTC2B's super wide dynamic range due to full bandwidth I Q demodulators feeding low level I-Q-Y matrixing to the CRT grids only. So I grab my Canon S40 digital and try to capture what I see. Results are disappointing to say the least. I tried everything possible with this full feature camera to no avail so far. If I manage a good shot, its got moiré that I can't get out. Surely there must be a technique described that will allow me to convey the picture quality of this 53yr old beast in digital camera form for emails and on the web? Anyone out there have good results or is my disappointing experience typical? I need to show the CTC2B's picture to some knowledge person on site in real time to get their opinion and critique.

I live in the country, 25mi north of Santa Barbara CA. This is wine and horse country, not techi antique Hi Fi, color TV and classic car country, so I don't communicate with anyone who shares my interests. If any of you ever get out my way, let me know, I'd surely like to show you what I got here. Right now is the best time, all the hills are lush green and the oak trees are fresh with new leaves .....Tom
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