Harry's at it again, Westinghouse this time

[miniman82]

Looks like a power chassis, but I know squat about these forgotten stepchildren of early color.

[ChrisW6ATV]

Originally Posted by Phil Nelson

A fascinating set from the technological viewpoint, but dang is that cabinet ugly.

Just my $0.02.

Phil Nelson

One thing about the CT-100, I really like how they look. This set kind of emphasizes how small the picture is compared to the cabinet, in contrast with the RCA. Regardless, I would love to have it anyway. Just no money in my budget even if it wasn't across the whole country, and it isn't going to sell for just $2200 in any case. I will be happy with my CT-100, and when funds are available they will go toward completing it and getting its restoration going.

[andy]

...

[JBL_1]

Originally Posted by rcafan

I have Had 2 ct100 over the years and the westy has better picture and Color. It's unusual color lock works well. I noticed the set that Harry

I would think at this stage all the early color sets all used the same tubes and phosphors and classic chroma demodulator gain and phase. Once phosphors shifted and people noticed that flesh tones looked different than they should designers started to spread the R-Y and B-Y demodulation angles and play with the gain ratios to get the color rendering they liked. Later went the color temperature started shifting up gains changed again.

Then came the boom of auto correction circuit. ACC was the first in the CTC-4 i think?Then came auto flesh circuits they pulled the phase of the chroma demodulator for a color close to flesh even closer. The auto flesh circuits that operated on color difference signals were less obnoxious than those that pulled the color sub-carrier.

Does anyone know if the Westinghouse have an ACC circuit?? Does it use a standard demodulator circuit?

[John Folsom]

rcafan, the 15" Westinghouse color set has a separate power supply chassis for B+ and filaments down below. How can you sen not have one? How about a photo of your chassis? I am very curious.

[John Folsom]

There was no ACC signal being broadcast in 1954-56. None of the early color sets had and automatic color correcting. They all used a color oscillator phase locked to the burst. Some designs had a crystal in the loop, others (like Westinghouse and Sparton) did not. The Westy used R-Y/B-Y demodulation as opposed to I/Q demodulation.

[stromberg6]

The ACC circuit in the 4 was used to control the gain of the bandpass amp, and depended on the strength of the burst signal. I've wondered if RCA issued a mod to bypass the ACC, allowing for manual-only control of the gain. There isn't any such mod in the lit I have on the 4, and my chassis has all the other mods.
Kevin

[old_coot88]

Gotta luv sitting in on this deep engineering arcana that the average tube jockey was never privy to 'back in the day'.

oc

[stromberg6]

Originally Posted by old_coot88

Gotta luv sitting in on this deep engineering arcana that the average tube jockey was never privy to 'back in the day'.

oc

Yes, we are fortunate not to have to make a living as tube jockeys. I was privileged to know many "old-timers" who did it for a living, and some were really talented and learned technicians, but many were tube jockeys, and winged it. The really good shops gained excellent reputations, as word of mouth spread, but still others did well because they were undercutting the "good guys".
I'm happy just to have a few hours a week to devote to vintage video and radio. If I ever retire, ha-ha, I have a bleep-load of projects just waiting to be attempted.
Kevin

[Sandy G]

Originally Posted by old_coot88

Gotta luv sitting in on this deep engineering arcana that the average tube jockey was never privy to 'back in the day'.

oc

Yeah, at the risk of sounding sacreligious, its kinda like lookin' over the Good Lord's shoulder & reading His "Crib Notes" when He made the World...

[JBL_1]

Originally Posted by John Folsom

There was no ACC signal being broadcast in 1954-56. None of the early color sets had and automatic color correcting. They all used a color oscillator phase locked to the burst. Some designs had a crystal in the loop, others (like Westinghouse and Sparton) did not. The Westy used R-Y/B-Y demodulation as opposed to I/Q demodulation.

Hey John, I wasn't talking about that GE VIR thing of the 70's. I was talking about compensating the chroma gain in the TV set for circumstances where the burst and chroma levels would be attenuated!

I and Q demodulation will give you the same color rendition as an R-Y /B-Y system if the gains and phases are set properly. You can't get the wide I channel but that is really hard to see.

[rcafan]

It was senior moment John! It's there.

[John Folsom]

Ah, good! :-)

[MelodyMaster]

Originally Posted by JBL_1

Hey John, I wasn't talking about that GE VIR thing of the 70's. I was talking about compensating the chroma gain in the TV set for circumstances where the burst and chroma levels would be attenuated!

I and Q demodulation will give you the same color rendition as an R-Y /B-Y system if the gains and phases are set properly. You can't get the wide I channel but that is really hard to see.

I would disagree, IQ demodulation gives a depth of yellows and oranges and subtle shading of flesh tones that just don't seem to exist in bandwidth-restricted RY demodulation. Case in point, I have a late-sixties Ikegami and mid 70s Conrac 19" rack monitor, both with Conrac broadcast tubes, both used as studio check monitors, both aligned to test instruments... the Ikegami uses IQ, and has a subtlety to the hues that the Conrac can't approach. Even my Admiral C322C1 with sulfide 21AZP22 doesn't have the rich reds of the Ikegami. (it uses RY) I have never seen any TV using simple quadrature that approaches he colour fidelity of a set using dual bandpass demodulation. This is one area where PAL definitely is at a disadvantage, since it doesn't HAVE a 1.5 Mhz modulation channel.

The irony, now that analog TV is on its way out, is that RY demod was used because it's easier and cheaper in the analog domain, and one could "play around" with the angles to "improve" flesh tones to compensate for picture tube colorimetry; you can't "play around" with IQ demod. But now digital methods make IQ demod easy, and a digital matrix can make any required adjustmant to vectors.

Part of the fascination of early colour sets is that the design did everything the hard way.

[jeyurkon]

Block diagram of H-840CK15