I think you are comparing apples to oranges here. :) NTSC monitors and TVs can display only so much picture information. Plasma displays are higher resolution with better contrast, but they can display more picture information than a NTSC set. Compare a really nice NTSC set of today to a roundie. There shouldn't be much difference.

And don't most color roundies contain a 3.59MHz crystal in their chroma oscillators? My Felton with a CTC9 chassis does. I know it's not much of a difference from NTSC's 3.58MHz, but maybe that could limit color reproduction, I really don't know. Can I replace the 3.59MHz crystal in my CTC9 with a 3.58MHz HC49/U crystal? Will that give me better color or is it just a waste of my time?

Jonathan

I've got three old 21" round color sets and love them to death but I'd have to be smoking something potent and illegal to agree that any of them even come close to a really nice bright 60" plasma set with 3000:1 contrast showing an HDTV program and at eye level on the wall instead of on the floor.

I didn't compared 30 or more years ago tv to lcd and plasma. I compared modern crt televisions to plasma and lcd. The difference is quite obvious if you have the chance to see an lcd and a picture tube type television at the same time, receiving the same signal. The lcd doesn't give the same quality at all! Perhaps in your country you have perfect tv signal or high definition ( anyway I don't remember having seen any tv with astonishing picture during my trip in u.s.a...) but also with a good digital signal ,in my opinion you can't compare a good picture tube based (recent) tv to a plasma or lcd! sorry!

A CRT of the same resolution as the LCD will give a better picture than a crappy LCD.

<rant>LCD TVs contain an LCD panel that can only display one resolution. If you watch 480p on an LCD at 1024x768, the 480p signal is upscaled to LCD resolution. It's pretty much the same with plasma TVs. If it's not a 1080i signal, then an LCD or plasma will look like crap. With CRT,you get a clarity you get nowhere else. The sharpest, clearest, and brightest pictures I've seen have only been on CRTs. I realize everyone loves the lightness and smallness of plasma and LCD, but they won't give you the sharpest picture. And with most properly aligned color roundies, the picture quality is just as good as any decent NTSC TV of today.</rant>

Jonathan

Fair enough I would not really say there's a great difference between a modern CRT set and a roundie other than a lot of the picture carved off by the roundies. Except of course when watching a DVD or something like that and you get twice the horizontal lines displayed or something like that.
I agree LCDs are at the bottom of the tv heap, but shouldn't the newest plasmas be pretty comparable to even a very good CRT? Seems like basically the same idea, a panel made of fixed phosphor-type pixels, except on a plasma, sharpness and convergence are both essentially perfect since there is no concerns about 3 different beams and how sharp each is. Maybe I would not have thought this when plasmas first came out but with the brightness and contrast going thru the roof on them lately, I think I'd pick one over a same-sized and priced CRT. (Low priced plasma, right!) I'd really like to hear an explanation of why a plasma would not have as 'sharp' a picture as a crt if it had the same # of fixed pixels (like CRT dots) except they are individually controlled with no convergence or beam alignment/spot size issues. Is there an issue as far as the ratio of black space between the CRT dots and between the plasma pixels? What is the contrast ratio of the best CRTs that are still made?
As far as standard def looking like crap on a plasma or LCD, to me that is a much more a byproduct of the picture being blown up to 50 or 60 inches vs. a 36 inch CRT. You're talking about making the picture 3 to 4 times the size so of course 'Gilligan's Island' eventually looks like garbage. If it wasn't for HDTV resolution, no way would I have sprung the $ for a set bigger than the CRTs I've owned.

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This is what I LOVE about this place;We have the "smarts" here enuff to have a complicated thing like CRTS Vs Plasma Vs. LCDs explained so even an old dummy like me could understand it-You'll NEVER hear a sales guy "'splain" it that way w/so much clarity...Doubt that many of 'em would know, anyhow...-Sandy G.

<<They also can't do continuous tones of brightness. You'll notice that continuous light to dark shades show up as bands of brightness.>>

So is that due to what you said about the difficulty in dimming the plasma dots compared to a CRT, or just that they aren't using enough brightness resolution when they are driven? I.e. even if you multiplied the resolution of the plasma's driver system by 100, the plasma dots are just not capable of showing that resolution anyway? Can you still see those bands when they are displaying HD? I never looked close enough to notice.

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One big design problem I've seen with plasmas especially is their use of COF(chip on film) ics.The actual drive ics for the plasma panel are mounted on the ribbon cables going to the panel.If one should fail they are not replaceable and the panel must be replaced.Usually causes vertical lines or horizontal lines in the picture.If they short they can shut the whole set down.None of the boards in Plasmas are component level repairable making them expensive to repair and have to get the propietary boards from the manufacturer.A lot of times they'll only sell the parts to a factory authorized repair center.Same with the boards in LCDs.The lamp is expensive in the DLPs and LCD projectors and short lived.Depending on use and on-off cylces I've seen a year or so on average.A lot fail long before a year is up.They advertise 2 years.Also Plasmas are power hogs.Look at the wattage rating on a Plasma.Some of them exceed the wattage of an old tube type color console.

I have an RCA (Thomson) CTC-185A7 19" set, bought new almost six years ago when I moved here. The set has worked just wonderfully all that time, with only a slight problem a few months after purchase (the RF connector for antenna/cable snapped off the tuner PC board). Other than that, the set works extremely well on cable (antennas don't work well in this area :no: ). The auto color circuits work very well also, as I have not had to adjust the onscreen color controls in months. It is for these reasons I intend to keep this set fully as long as it works as well as it does. Digital? Doesn't bother me. I use the set with a cable box now, so if I still have this set when everything goes all-digital, all I'll have to do is call the cable company and have them put in a HD-capable box--if the one I'm using now won't handle the new channels, that is.

I agree with the posters here who have said that plasmas and LCDs, particularly the former, still have bugs which must be worked out. I was particularly interested in one post, in which the writer said some LCDs now are built with some of the video ICs actually incorporated in a cable which requires the entire panel to be replaced if those ICs go bad. The projection lamps in DLPs and other projection HDTV sets are something else yet again. These lamps can open after only a year or two, depending entirely on how much the set is used, and are expensive as all get-out to replace (I saw one for an RCA/Thomson projection set listed for something like $400). Compare this with standard TV CRTs. If you get a good one in a modern analog set, it can last years. (The CRT in my set is the original and still looks as good as the day I purchased the TV; I had a Zenith b&w solid-state 12" portable that was still making a great picture on its original CRT, after 22 years, and I also have a 10-year-old Zenith Sentry 2, original CRT and fantastic picture.)

There are still problems with image burn-in in plasmas. I was browsing ebay earlier this evening and saw a listing for an RCA or Zenith 27" CRT set, in which the seller mentioned the burn-in problem with plasmas and that the CRT set he was selling could last another 25 years without the tube burning out or burning up the screen. Some day, plasma panels will have a similar reliability record (with the panel lasting up to, say, ten years or so; I wouldn't expect a plasma or LCD to last anywhere near 25 years), but the current technology is still new enough that it has bugs in it yet. Perhaps when all TV is digital in 2009 (or whenever; I read recently where some Washington bigwigs are trying to move the deadline up to late 2006 or 2007) this may change for the better, but for the time being we are stuck with what's currently available. Compare today's plasma sets with the first CRT televisions 55+ years ago. Back then, the idea of sending pictures over the air was new, and the technology to receive those images was primitive by today's standards. The same thing can be said for today's plasma/LCD TVs. The technology is still very new and has more than a few bugs (heck, even some TV stations are having problems with their digital signals; for example, several stations in Cleveland are transmitting poor-quality, on-again off-again DTV signals because of problems with the transmitters and so forth), so it is not realistic, IMHO, to come to the conclusion that digital or HDTV has "arrived" yet. Far from it. In five years, maybe, but for now the technology is still evolving, so we have to tolerate the bugs in the current system. Speaking for myself, I won't even think of getting a flat-panel plasma or LCD TV until they work as well as and are as reliable as any good CRT set.

IMHO, the FCC really jumped the gun on HDTV and DTV. Hey look, the standard was hammered out in '98. Well, video codecs, processors, etc have advanced lightyears since then. We're stuck with a 1998 standard though. At least NTSC left some wiggle room, and NTSC was better than could be achived practically in the 50's anyway.

Do any NTSC TVs today even come with full I/Q demod, or NTSC correct phosphors? The former should be a no brainer - it's just another few transistors on a chip. The latter? Aren't there tinted phosphors that can get you there, too?

Actually, didn't RCA's colortrak have I/Q, along with some Panasonics?

Actually the FCC almost went with an analog style HDTV system. Something like the Japanese MUSE HD system. Then some company announced that they could do an all digital system with compression that would make an HDTV signal fit in a 6MHz TV channel. The FCC said "Great, do some refinements, field test it and make it good, and we'll do it, an all digital HDTV standard". About the only real arguement was about the transport stream modulation onto the TV channel, 8VSB or COFDM. COFDM is a little better with ghosting, but with its 2000 or 8000 subcarriers, severe clipping in transmitters and intermod in receivers is a big problem. If all 8000 subcarriers decide to turn completely on full ampliitude at the same time, you'd have a huge power spike to try to transmit or receive without overload.

With my over the air HDTV reception and quality, the ONLY complaint I have is when networks add those stupid subchannels. It almost exclusively affects 1080i main channels quality, you start to get pixelization, sometimes not even on fast motion. Here in Los Angeles area it's NBC which is 1080i and one stupid weather subchannel. Other night on Conan, they had Dolly Parton on, and just her slightly moving around and her large amount of hair made pixelization around her chin and neck that looked awful. Jeez NBC who were the forerunners of color can't even show someone sitting in a chair talking and no camera movement without it degrading?? Also it may be a problem of them not broadcasting using the full 19mbs or something but I have no idea how to measure it. But they are by far the worst out here. Otherwise CBS, ABC etc look great out here and to me HDTV looks incredible unless they screw it up and don't give a damn like NBC L.A. Really hard to believe the people there just accept this lousy quality, sometimes NTSC would look BETTER! The TWO subchannels have almost no effect on ABC out here which is 720p. CBS is superb, 1080i and no stinking subs. I'm using a 51 inch crt-based projection Hitachi.

It's the old 'It's digital, it's a computer, it's perfect' syndrome. Just like most CDs are done like crap these days because, hey, it's digital, it's perfect....

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Or ads for satellite tv I hear constantly where the guy asks the announcer - "with digial quality?". Yup. Lousy quality! Yeah you lose the static and shadows but get pixelization and artifacts.

Same here on the east coast. WCBS New York: no subs. But the WB channel has a 1080i sub on its 1080i main channel. I don't/won't watch it out of spite. :D

Not watching the WB out of spite is the same as "not" poking your eye with a stick because you hate trees. I don't even have a digital TV, yet I have no problem ignoring the WB! :D

Back in 1988 I won an RCA Dimensia 27" floor model console in a contest (I could never have had to been able to justify buying it as I was in the process of restoring 2! CT-100's at the time, John Folsom now owns one of those 2). The Dimensia had wide I and Q demod on chip! Upon completion of the first CT, I parked it next to the Dimensia with a parallel RF feed. The similarities in the color reproduction was nothing short of amazing. The only plusses to the Dim. other than acreage was overall brightness and HV regulation. Even the signal sens. was comperable. I played that Dimensia brutally until '03 when the crt started to slide! Not too shabby. I still have it in queue waiting for rebuild. One of my all time worst offenders of the faith candidates is the RCA CTC-18x family. I quit counting how many of them I've had to do the tuner ground resolder routine (along with Bad regulator darlingtons, regulator ic's, up in smoke yokes, HOT's, and oh yes, EEproms!) I'll still fish them out of dumpsters, but only if they are near the top with no soured milk or other grossities stuck to them.

Oh yeah, I nearly forgot that a friend of mine ( he's still a friend in spite of this) knowing my reluctance to throw away anything tv related, gave me a '67 vintage Motorola 21" rect. tube floor model. Since then I've only seen one other rect. 21" floor model and that was an RCA XL-100 and that was a pretty decent set. This set had a Channel Master CRT in it in good shape and the cabinet was mint. Thats all I have good to say about it as far as my initial assesment goes. Aside from half the tubes in it testing marginal, the horizontal output tube was cracked and the flyback melted (then I got to looking at the Sams for it and noticed their novel 1! tube based color demod circuit and how it resembled the one that was used in the Magnacrap tube chassis - the one with the push pull focus control - and neeeever looked good to me). Anyway, I thought about risking censure by the collecting community and going ahead and making a bookcase or a bonfire out of it. Then it dawned on me, the entire front mask assembly was identical to a TS-919 gen 1 Quasar table top set I had "restored" and was very fond of except for it's scratched up contact paper on steel cabinet. They even both had the tint control (like the maggie chromatune control) and the convergence paanels were in the same place behind the speaker! Needless to say, I have the only floor model 21" Quasar I've ever laid eyeballs on and it is a sweet little set (the ho-made back cover looks a little cheesy but it keeps the cat alive). If anybody has a better use for one of these abomin-ola's, let me know.

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I don't beleive anyone is doing a 1080i sub on top of a 1080i main - what you are probably seeing is the same as what WGN (WB channel in Chicago) is doing - two program table entries for the same video, perhaps with Spanish audio on the second entry when available.

Yeah, thats my set. flattest crt I had seen up till that time and a multi-funtion remote that will still control most RCA products(even my Proscan vcr). I did have the typical scan rectifier board solder problems and the ex - XYL snatched ant. 1 coax connector out of the tuner can, but with a little weller and 90/10, I WON! Wow, what a contrast to those mid 90's CTC-18x dumpster dunnage sets , huh?

That Dimensia IQ demod design was ingenious in that they found a way to make an I channel delay line with only one IC pin (plus one external transistor). As an analog IC designer, I thought that was one of the neatest tricks I ever saw. Essentially, they tied the input of the delay line to ground, then drove the delay line output and what would normally be the delay line ground up and down with the input "I" baseband voltage. They then used the same driving pin to sense the output current!

Despite my admiration for the IC design, When I tested one of those sets for chroma resolution (working at Zenith), it was essentially no better than the R-Y/B-Y sets. The I channel high frequencies were quite attenuated. It appeared that there was too much phase distortion in the IF to allow the I channel high frequencies to be boosted to a useful level. I went through some effort to design a better IF for a possible wideband design myself, but concluded that the NTSC got away with their system design partly because tests were done on small screens. My basic conclusion was that NTSC needed a more symmetrical Q filter in the transmitter - it should have traps on the upper and lower edge that match the 4.5 MHz sound trap (+/- 900 kHz from the chroma carrier). If the Q sidebands transmitted would be sharply curtailed beyond +/- 500 kHz, there could be no quadrature crosstalk from Q into I, and it would behave like the NTSC intended - but NTSC Q filter specs were too broad, and any reasonable IF would show quadrature distortion and therefore the I response could not be boosted to the theoretical value. I proved this by modifying the filters in an NTSC encoder -and when we saw how well it worked, we gave up trying to design an I/Q set, since there was no way to go back and modify every encoder out there.

Gee, it's a shame I don't live near the Illinois area Old Tv nut, I would really love to pick your brain more intensely! An old friend of mine who just recently passed was a long time employee and xmtr super for our local CBS afilliate. When I got eat up with the vintage color bug in the 80's, we talked at lenght about the challenge of getting a color signal through those old RCA 25kw coffee cans and on the air. Seems as though there was an issue with dfferential phase distortion that reeked havoc with satisfactory hue reproduction and that it was more apparent on I/Q sets. BTW, was RCA the only man. to try and reintroduce I/Q demods in the 80's and didn't this coincide with their introduction of real comb filters? Shame they didn't have those in "54. Sorry if I'm off thread topic.

Well, okay, that means it isn’t a bad as it looks. And you’re right about the Spanish audio — but I’m still not watching the WB!

Here’s what I misinterpreted.

In the NYC reception area, WPIX channel 11 is the NTSC WB over-the-air signal. UHF channel 33 is the actual ATSC broadcast channel for the WB. (To reduce confusion, the actual broadcast channel doesn’t appear; it is replaced with the NTSC channel designation with a -n to indicate the individual, or sub, channels.)

As you can see in these screen shots taken last night, the channel 11-1 WPIX-DT image shows an icon for Dolby digital 5.1 as opposed to the channel 11-2 image with its icon for Dolby digital stereo (sometimes in Spanish).

It’s the same 16:9 1080i HD video; just the audio changes. I feel better about the technical thing, but I’m still not watching the WB! :no:

May I add that once Thomson took over, RCA went so down hill that I never bother with their products again. It's a shame they took them over and went with cheap designs, parts, and manufactoring. I do like most of their directv receivers and HDTV receivers, but that it pretty much it.

old_tv_nut, you know so much. I want to be an engineer like you doing analog designs. :)

Pete, what kind of HD receiver is that?

Thanks.

Jonathan

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It's quite a shame now, but modern tv stations and programming is going down the toilet. :(

Jonathan

infromercials
 

Don't forget about the infromercials, seems like theres more and more stations are running them where other programs used to be. I can remember one day when all of the local stations with the exception of PBS, where running them. Then I click over to some some low power independent station coming in from who knows where, very poor reception in and out. Channel 11 I think. Was running I love Lucy.

I have figgered out a way to put the infomercial blitzkrieg to use. It is a sigal to me to turn off the silicon sandman an go crawl in the back of an old Zenith or under the hood of my Z-28.

Exactly. Much in the same way of radio. The only thing I listen to anymore is my local NPR station on FM and as far as TV goes, it's more miss than hit there.

circa 2003, 52-inch projection w/built-in ATSC tuner, RCA HD52W140

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There are three kinds of phase distoriton that can happen in an NTSC transmitter. The "indcidental phase distortion" is a non-linear effect where the chroma phase is changed according to the luma it's riding on - so bright parts of a face get a different hue compared to the shadows. Then there are two linear distoritions: if the tramsmitter doesn't have a flat frequency response, it will roll off the upper chroma sidebands - this makes the Q sidebands non-symmentrical, causing crosstalk into the I channel of an I/Q set. The receiver IF can do the same thing. I think that's part of what I was seeing in the receiver. Third, the transmitter can have a poor phase response near the band edge (due to sound diplexer), which causes color transients (edges) to be wrong. Probably some of that in the receiver too. NTSC specifies the group delay response of the transmitter be precorrected to match the NTSC committee's idea of what a receiver IF would do. (Called a "Friedendall" precorrection filter after the guy who managed to design a workable one.) PAL does not use a precorrection, and lets any phase (hue) distortion be cancelled by the alternating phase.

As far as comb filters, reasonable ones came in in the mid 60's with the invention fo the glass delay line for PAL, so this wasn't really tied to the abortive I/Q revival.

Sounds like that incidental phase distortion must be similar to IM distortion in audio. I bet that I've seen this in older sets and thought it was localized purity problems due to mask doming on strong beam current on bright fleshtones. NTSC color transmission fascinates me as much now as it did 20 years ago. I,ve met a lot of good bench techs that really don't fully understand color transmission and reception but are competant none the less. I'm just a restless inquiring mind I reckon. One of my pet projects that I've already taken one stab at is a homebrew matrix adder similar to the one in a CT-100 that I want to apply after a Zenith Beam demod. section just to see what improvement it would have over the typical 60's crt matrix. I've got a copy of the schematic for 15" Zenith set and it appears that is what they were doing there. I'm hoping for an all tube circuit that will come close to those tight black levels and improved gamma that I see on those first gen. chromacolor sets. If that works out, maybe add driven clamps for DC restoration ( I,m gettin a little carried away now..). Anyway, it seems to me that the luma/chroma area of a color set has to have some complexity for a good picture. It seem to me that the "simple" one tube approach in those old Motorola's an Maggies just didn't cut the mustard to my eyes. They should have stuck with cloning RCA's ( i'll still keep em around, space permitting).

In the "conflict" CRT vs Plasma/LCD: I think the peoples want LCD/Plasma tv's because for 2 BIG reasons:
- 1. The LCD/Plasma tv's and monitors are friendly with your eyes (for eg., if you stay too much with yout eyes in the fornt of an old CRT tv, your eyes will hurt you after a time)
- 2.They are space saving
Well, the big problem with the LCD/Plasma tv's and monitors is that the image haves lower qualty than at an CRT tv/monitor (I only watch normal television, not HDTV, maybe in HDTV the image provided by the LCD/Plasma tv's is better; I saw an 16:9 17"? monitor conected to an "Apple" computer that provided an image way above than that provided by CRT's monitors-well that moniutor cost unleas $1000); and another problem with the LCD/Plasma tv's/momitors is that of the side wiew: if you stay to much on the left or on the right side of the screen you risk to see nothing.
I have a question: there is an adapter that allows you to conect an roudie to HDTV?

I've got a 1995 Zenith 19" Sentry 2 also. Been my main TV the entire almost 11 years now. Never had a problem with it. Been used TONS. No problems.

Los Angeles channel 5 WB (KTLA) does the same thing, I was told this does not use any more bandwidth than one main channel since it's the same data. It's an excellent digital channel out here, they zoom in on almost everything fully or nearly fully so not much in the way of annoying black or grey side bars, only channel in LA that does that. They really do a good job at it too as I never seem to notice stuff getting chopped off vertically, maybe they zoom a little and stretch a little, but it looks great. Don't know if it's WB doing it or KTLA.

My Hitachi HDTV has video or RF outputs but you have to have the TV on to use them, but yes I can just run that into a video/audio box that converts to RF, or right from the RF out to the antenna of any of my old tvs. Probably applies to any of the hdtv standalone tuners I would think, but not sure.