This one is for the guys who are either old timers, or have a fair sized collection.

What is the highest performance B&W TV from the mid to late 50s?

By high performance I mean all features which contribute to picture quality. Sharpness, contrast ratio, geometry, etc. Sensistivity is less of an issue these days with the death of OTA broadcast.

As someone whose main exposure to tvs of this era comes from reading old magazines like Radio & TV News, my guess would be one of the souped up RCA 630 clones from the mid 50s, with a 21" picture tube, would be the thing to look for.

An issue to contend with in the later 50's is that the B&W TV designers would limit the video bandwidth to suppress the NTSC color chroma subcarrier. That subcarrier ranging from about 2MHz and up. The chroma subcarrier would appear, on high resolution early B&W sets, as a crawling fine checkerboard pattern in highly saturated color areas of the picture.

Usually, they used the response of the IF strip to do the above chroma subcarrier supression.

One high performance feature that most every TV set manufacturer left out was DC restoration. Without DC restoration, a night scene (picture being mostly dark) the blacks go gray after the TV show switches from a bright sunny day (lots of white in the picture). Most color TVs did have this feature, as gray dark colored areas look really awful, washed out looking. For some reason this doesn't look quite as awful in B&W.

Nothing specific her but probably something from Zenith.

Pre-53 sets with wide bandwidth and DC restoration are the things that make the sets high class.

The epitome of best quality RCA B&W sets was 1951-52, just before color. Four IF stages with 4MHz bandwidth and DC coupled video amplifiers really counts for getting a good picture.

I also think printed circuits with tubes is a bad thing. That is why Zenith touted "hand wired quality" long after almost all other set makers went to printed circuits.

This reminds me of an incident a few years back when I was looking or a Zenith Silver Sensor antenna. She was about 20 years old and she didn't know what Zenith was. I said "you know.. the quality goes in before the name goes on" and she thought I was crazy.

Like maxhifi , this has been a question that has been on my mind . I am relatively new to this hobby/addiction and am looking for my next project. Since I am the world's slowest technician , it will be awhile , so I have time to scout around for the next victim. My next set should be a stand alone television without radio or phonograph. At the present time , I have no interest in color , so I am looking for a set that is 'as good as it gets' for b/w. I'm not looking for anything that is rare or hard to find, just a solid performer. Anybody got a specific make and chassis to look out for? As a side note, there is a user on this forum (John Marinello) that has an avatar of a set that I just can't get over. I don't know anything about the chassis or performance of 'Byron' but for looks I think that's 'about as good as it gets'.

I'd have to say the DuMont 1-piece chassis from 1947-50 with the Mallory Inputuner. Those were used in DuMont, Stromberg-Carlson, and Crosley TVs. Built as close to mil-spec as you can get!

Charles

I was just going to jump in and recommend my 58 24" Space Command orphan that eventually someone is going to frag me for mentioning, but then I saw the DuMont recommendation. For what must have been the ultimate in overkill, I would definitely speak highly of that era of Dumont sets. However, I tend to believe that less bells and whistles simply leaves less to go wrong, not just in electronics, but in most things; especially cars. The more basic the car, the less problems arise. One must understand that I am of the mind that sees the Volkswagen Beetle as an ingenious engineering feat. Not necessarily the actual car, but the idea of one style that changed little, so common mechanics eventually became experts and parts were cheap and backward compatible. It would seem that is what we need now, but I have always felt that the cars were removed from our economy due (besides safety issues) to lasting too long and offering far less opportunity to gouge owners at the dealership. It seems that products that last as long as the payment book and warranty, then are deemed obsolete, are the way these days. Sorry, I sort of went off topic.......

This is interesting in that there's not clear consensus, but plenty to look for. The main reason I said 1955+ was so the set would have an aluminized picture tube, but i haven't seen many later sets with dc restoration, and intercarrier sound is somewhat of a drawback too in that white text makes the annoying buzz sound. I think 17 inches is about a perfect size for a TV screen, as far as I am concerned.

With the desire for an aluminized crt, are you trying to avoid dealing with an ion trap magnet? I have never been quite clear on the ins and outs of aluminized tubes. The has been discussion here before on the subject that led me to believe that if a tube was aluminized that it would not require an ion trap. However, my Sylvania tube guide lists aluminized tubes WITH an ion trap if I am not mistaken.

well, it's not the ion trap
In addition to avoiding the ion trap, the aluminum layer prevents light from the phosphor from lighting up the inside of the tube... Result being improved contrast when scene has both light and dark elements due to absense of reflected light washing out the dark parts of picture

The RCA 21" metal sets from around 56-58 had nice pictures , usually balck cabinet with channel knob , volume/contrast on the side , below them a little door that had brightness , vertical and horz , but like other i'd say i agree about the dumont statements but would add that the RCA 10" sets like 8-t-241 , 9-t-246 Produce great images like the dumonts ... i don't know what the Zenith 21" sets were like in the late 50's but the 23" and 19" zeniths of the 60-66 era had great images , so maybe RCA , i don't recall if the 14" and 17" zeniths of that period had great images , perhaps someone knows what other makes had like sylvania , emerson , etc

Mike

When you saw a 21" set with two 5U4's, it generally was a higher performance model. A lot of mid 50's RCA's were like that. The only thing that was a problem was that lousy 21AP4 CRT. I think the 1954 model year, they went to glass CRT's.

I collect the Hoffman Easy Vision TVs and the Mark V chassis has 4 IFs and a true limiter in the sound stage(this removes almost all of the buzz). The rest of the TV design is of high quality also. However, I do not believe that it has DC restoration. Of course, you have to live with living Black and Green, not living Black and White due to the green tinted safety glass Hoffman used at that time.

As to cars, my wifes Ford Escort has gone almost 200,000 miles with no engine/transmission trouble. My grandfathers 1953 Ford went 170,000 miles (at 45 MPH-he was a slow driver), then broke an engine ring. Due to this kind of stuff, I think cars are as good as they ever were, if not better. They are better in fuel economy(fuel injection), safety, etc. If they are worse, it is in the plastic trim(hubcaps and such) that are used now. From my experience, reliablity is at least as good, if not better than older cars.

When you saw a 21" set with two 5U4's, it generally was a higher performance model. A lot of mid 50's RCA's were like that. The only thing that was a problem was that lousy 21AP4 CRT. I think the 1954 model year, they went to glass CRT's.

Or P-P output tubes for the audio! Some of the higher end late 50's Zeniths had the claim as being "fringe" reception sets as well as some models with two rectifiers.

I was thinking DuMont--but that's more for the cabinetry than the circuitry in a lot of cases (the radio's and phono's in them were NOT so great) and the I think only the top of the line DuMonts had DC resto.

Someone mentioned Stromberg Carlson-I agree they are built like milspec gear. Once had a 6BQ5 integrated stereo amp by them which was heavy and sounded great.

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hi andy,
I want to do this to my RCA 8PT... I was looking at the 630 schematic and it does look like just a diode, but that set drives the grid of the crt and is very different to my 8pt Can you provide a bit more specific info about how to do this? It would be much appreciated.

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Andy, what value are you using for the diode?

i don't remember the 60's zenith sets i watched do this with the blacks , they had blacks and black at fade out , i know this 61 motorola i have that was part of a tv sales/repair that never sold does this , night scenes are very gray, i don't seem to remeber the rca 8-t-241 do it but its been a while since i've run it

mike

When I had my Magnavox CT-246 16" tv/radio/phono console working briefly in 1980-81, I remember how nice it was to have DC restoration on a B&W TV.

Andy,

Finally have some time to look at the TV. Is this (attached) what you have in mind? Just want to confirm before I start work. Also, does it work a lot better with a Ge diode, or does a Si diode suffice?

Took me a bit to find my schematic of my Truetone. I would give this set high marks. 4 video IF's, dc restoration, dual chokes in the B+ supply (no focus coil as a choke, two actual chokes)! A rather interesting AGC circuit and a tuner that is absolutely bizarre. It even has a spot killer for the CRT on turn-off! Intercarrier IF.
Mine is in poor condition (mice!) so it may end up a "Frankenset". The tuner is more than a "basketcase" and without analog, it may be fun to set it up for composite video.
The only thing I see it lacking would be a limiter in the audio circuit.
And the original CRT is good!

Andy,

Finally have some time to look at the TV. Is this (attached) what you have in mind? Just want to confirm before I start work. Also, does it work a lot better with a Ge diode, or does a Si diode suffice?

My guess is silicon, because the video swing is probably 50V pp or more?

Can this be used on other sets?

I've always lamented the lack of DC resto in my Emerson 1224 (which, for some reason, seems especially bad among old B&W sets - any significant white in the picture, and anything else in the picture turns to solid black), and am dying to try it on my set.

Zenith made a line of top-of-the-line chassis' in the late 1950 through 1963 that had switchable DC restoration from the front of the set. They called it "dynamic contrast" or "dynamic picture" as I remember it. It was a push-pull switch on the back of one of the picture controls under the screen.

Those same sets, while having only 3 IF stages, also used a new tube at the time. The 6EJ/EH7 was capable of much higher gain that previously used tubes, so they had wideband IFs with gain.

These were 21" and/or 23" sets. I've worked on a few when I worked in a service shop, and my great grandmother had one. I've never seen a better picture on a B/W TV set. In fact, I'd say those particular Zenith chassis were THE BEST monochrome chassis ever made, hands down, over and above ANY other manufacturer.

One other cool set I know of with DC restoration was the first Magnavox solid state or "astrosonic" large screen TV chassis. Introduced in 1965, it has DC coupled video amp stages, and most came with a 24" or 27" inch CRT. We had a stereo theatre in danish modern with this TV chassis, and the common astrosonic radio chassis of the day and a micromatic changer. It seemed to play forever with very little trouble, and still worked well when I got our first color set. I'd like to find one of those, but I've never seen another since the one my family had. I don't think they sold many as those with the money for a combo like that prolly went for color.

just my $.02.

I can vouch for everything TV Engineer wrote. I had a 1963 Zenith 23" console which produced probably the best picture I ever saw on a b&w set. It had three IF stages, two 6EH7s and a 6EJ7, but no dynamic picture control, though it did have a "peak picture" control on the front panel, behind the drop-down secondary-control door below the CRT. The audio was great as well, owing to the set's 6x9 speaker and 6BN6/6BQ5 audio stage. They don't make them like that anymore.

What about "Mil-Spec" monitors ? Would they have been built to higher standards than civilian TVs were ?

Black-and-white CCTV monitors often have DC restoration, and one model I know of has a switch for it on the back panel. These are 9" and 12" monitors though; the biggest I have seen for sale in recent years was a 20" version.

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That should work on most sets. The only thing that could go wrong is if the video output is feeding the sync circuit it can cause instability. If it does, get rid of the cap and it may be ok. You'll lose some DC restoration, but it's still better than nothing. The type of diode isn't critical as long as it can handle the voltage.

I'd use a 1N914 or a 1N4148. These are high speed diodes. Also, placing a small resistor [~1K] in series with the diode on the capacitor end will improve the dc restorer action.

Some early sets with superior performance are the Radio Craftsman sets for building into a wall or cabinet, and some by Altec Lansing. Conrac made sets like this with remote tuners and also under the name Fleetwood. Both Tech-Master and U.S. Television produced high quality build-in sets as well.
Cliff