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Reinhard
01-07-2016, 11:24 PM
Hi,

I'm 65, a just retired electrical engineer from Bell Labs/AT&T/Lucent. When I was 15 in 1965 and tinkering with all things electronic, my dad signed me up for a vocational school TV repair class, taught by the owner of a local repair shop. Needless to say, I was the youngest in the class! But it launched me on a sideline TV repair hobby that ended up paying for a good portion of college eventually, and got me enamored with the technology, and got free discarded and then repaired color TVs into our family room, when they were still pretty expensive!

But, here's the important, and ultimately unfortunate part of this story: Because of my great interest and youth, the repair shop owner and class instructor gave me a vintage color TV, which was described to me as an RCA prototype, which I actually got to work, though not very well. At the time I had no formal electronics education and only learned by trial and error. In the end, the TV's performance was so unstable, and my parents annoyed by its bulky presence, that I reduced it to parts, for curiosity and use in other projects.

To this day, I don't know exactly what it was, except it did not say CT-100 on it, but it was RCA. I already had Grob's book with the -100 schematic foldout in it, and it did not match this TV. I was told it was made in the 1950-1952 time frame. What I recall also is that it had about 43 or 44 tubes and two chassis, and if I remember correctly 5U4 rectifiers in sockets on top of the two power transformers. I could be wrong about this detail - time fogs the mind some - but I also seem to remember the tube was metal, because I remember a big white polyethylene high voltage shield around it. And the shadow mask and glass phosphor dot plate were in a somewhat self continued assembly inside the front of the tube. Unfortunately, my curiosity led me to dismember it as well. Does anyone have any idea what this set might have been? In any case, I kick myself over and over that in my youthful ignorance I destroyed a piece of history!

Electronic M
01-08-2016, 12:03 AM
The model 5 prototype was IIRC the last before the CT-100 (and nearly identical to it), and I hear the 4 used selenium rectifiers for the B+ so it was probably an earlier prototype....

What a shame that it was destroyed, CT-100 and Model 5 sets have fetched as much as $10K in the past...There may not be another one like that left.

About the only pre-model 5 proto type in existence that I know of is owned by my friend Nick Williams (Miniman82) and probably is still on display at the Early Television Museum.

Reinhard
01-08-2016, 11:42 AM
Thanks for the info. Yes, having recently found out about the museum, I plan to go visit it soon....seems I'm on a nostalgia streak. BTW, I grew up in Milwaukee, and the subject color TV prototype came from a repair shop around the corner from 35th an Oklahoma....don't know how the shop owner came to a have it. It's tough to know closer to the origin that an item will some day be a collectible. However, I'm also a big Tektronix fan, and have a small collection of landmark Tek pieces. I have what is likely one of, if not the last 485 scope produced, in pristine working condition. Got started with the fascination with CRTs when I was 11 and a kid in my grade school gave me a 7JP4, which I was bound and determined to light up, and succeeded, with a train transformer, old radio vibrator, and car ignition coil....just a bright spot in the middle! Unfortunately, again I had to know how the insides of that tube were made, so it came apart as well. I guess those you can still find reasonably on eBay. Does the museum have an electostatic deflection TV with the 7JP4? Would love to see one work!

Cheers!
Reinhard Metz
Wheaton, Il.

Electronic M
01-08-2016, 02:06 PM
Thanks for the info. Yes, having recently found out about the museum, I plan to go visit it soon....seems I'm on a nostalgia streak. BTW, I grew up in Milwaukee, and the subject color TV prototype came from a repair shop around the corner from 35th an Oklahoma....don't know how the shop owner came to a have it. It's tough to know closer to the origin that an item will some day be a collectible. However, I'm also a big Tektronix fan, and have a small collection of landmark Tek pieces. I have what is likely one of, if not the last 485 scope produced, in pristine working condition. Got started with the fascination with CRTs when I was 11 and a kid in my grade school gave me a 7JP4, which I was bound and determined to light up, and succeeded, with a train transformer, old radio vibrator, and car ignition coil....just a bright spot in the middle! Unfortunately, again I had to know how the insides of that tube were made, so it came apart as well. I guess those you can still find reasonably on eBay. Does the museum have an electostatic deflection TV with the 7JP4? Would love to see one work!

Cheers!
Reinhard Metz
Wheaton, Il.

They have several. http://www.earlytelevision.org/
You may be able to buy one at the spring convention/swapmeet/auction.

I've got 3 7JP4s and 2 sets that use them. The Motorola VT-71 is the most common set that uses that tube.

electronjohn
01-10-2016, 09:48 AM
Welcome to VK!