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  #31  
Old 10-12-2016, 07:16 PM
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M3-SRT8 M3-SRT8 is offline
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Oh, I would love to see that Stalin era television in operation.

With some vintage Soviet anti-west propaganda, Stalin and the Crew reviewing the October military parades, show trial footage, etc.
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  #32  
Old 10-12-2016, 08:48 PM
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https://www.youtube.com/watch?v=5CaMUfxVJVQ
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  #33  
Old 10-13-2016, 09:30 AM
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Originally Posted by old_coot88 View Post
"Pay attention, please. Thank you!"

"Is day wear!"

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  #34  
Old 10-13-2016, 03:23 PM
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Great find!
Too bad the crt was damaged on Transport. VEB RFT was a TV manufacturer in East Germany

http://www.radiomuseum.org/dsp_herst...company_id=553.

Maybe you are lucky and will find a picture tube in Germany.

Greetings Josef
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  #35  
Old 10-15-2016, 04:03 PM
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This is an incredible piece of History! I wish you all the luck on finding a correct replacement CRT.
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  #36  
Old 04-25-2017, 01:11 AM
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It's a pity that I haven't been on the forum for a while and missed the discussion about that wonderful television, it's time to catch up:



The Leningrad-T2 television was introduced in 1949 as a greatly improved version of the preceding Leningrad-T1 set (1947). According to the early Russian classification, the Leningrad-T2 employs a 9" round picture tube (T1 = 7", T2 = 9", T3 = 12") with magnetic deflection and focusing. The set features a LW/AM/SW radio assembled on a small subchassis attached to the underside of the top panel, and provides FM reception through the audio section of the TV as well. The television was positioned as rather luxurious (just look at the cabinet!), so it came pretty costly in comparison with the extremely popular inexpensive 7" KVN-49 set launched about a year earlier:



The Leningrad-T3, a kingly 12" console version of the set, was produced at the same time in small quantities. It added a phonograph, a top-end multiband radio receiver featuring a motorized tuning/AFC, and a high-fidelity push-pull audio section:


[rw6ase.narod.ru]

The interesting thing is that in addition to the originating Kazitsky plant in Leningrad/St.Petersburg, the T2 television was produced by the Sachsenwerk factory in East Germany as well. In 1949 the factory was involved in postwar reparational service, was equipped with some production lines from the Kazitsky plant, and began to produce exactly the same television but with the use of some German components as well. The production of the model had discontinued in Russia in 1951, and in Germany in 1953, thus a Russian-made Leningrad-T2 has become even more rare than the German one.

The design of the T2’s cabinet appears rather distinctive. The 9" round picture tube sits on the right side of the cabinet, while the left side is occupied by an 8" speaker. Yet, the set looks symmetrical due to the two mirror-like grills:



The grills look similar but the right one is actually a slidable curtain which can be slid to the left, revealing a veneered screen bezel. The bezel is slidable too, providing an easy access to the picture tube, if necessary. There are six controls on the front of the cabinet. The leftmost one is a coaxial volume/tone control combined with the power switch, the others adjust focusing, contrast, brightness, and fine tuning. The rightmost knob is a channel/mode selector. It looks like a coaxial control, but that's a trick for the sake of symmetry - both parts of the knob sit on a common shaft and act as a single knob. The radio control panel built into the top panel of the cabinet appears to be symmetric as well.

As for electronic design, it comes pretty typical for the time. The set uses a "split sound" audio system, so the total number of tubes is about 30 (the schematic is clickable):





The wafer-type tuner receives 3 channels, and has an extra coil providing FM reception. It was more than enough for postwar Eurasia due to very few stations existing on the continent at the time. The next two steps of the channel/mode selector engage FM and AM reception, accordingly. When the selector passes from television to radio mode (i.e. from 3rd to 4th step), the tenon attached to its shaft toggles a special switch turning off the television part of the circuitry:



The signal path starts from the coaxial-type aperiodic 75-ohm antenna input. Then, the signal is amplified by the single tuned RF stage with variable gain controlled by the contrast knob. The audio IF signal is split off after the converter and passes through the three stages of the audio IF amplifier, ending with the limiter and discriminator. Even though the video IF amplifier consists of as few as two stages, the set manages to show a decent sensitivity, I believe due to the designer's choice of high-gain tubes in combination with an "overcoupled" way of forming the needed frequency response. The video section ends up with the detector and the two-stage video amplifier with a DC restorer. The picture tube is driven via the cathode, while the grid is used for the brightness control.

The video IF and synchronization sections were the weak points of the previous Leningrad-T1 model, so they received a lot of designer's attention and were significantly improved. As you might know, Russia was the first country to develop and adopt the new 625/50 broadcasting standard. The T1 was designed to meet the both prewar and newly-accepted standards, but for the new one the bandpass of its video IF amplifier was found to be too narrow causing complaints of poor sharpness. The bandpass of the T2's video section was widened up to almost 6 MHz to realize the advantages of the new standard. The sync section was improved as well, from the basic amplitude selector/clipper known from the prewar times to a pretty complex system employing as many as 3 tubes. The manufacturer's specs declared good synchronization even in weak signal conditions, and perfect interlacing.

The sweep sections are conventional for the time, but with an exception: whereas the lack of special television tubes caused the use of general purpose tubes in TV sweep circuits up to the early 50s, the Leningrad-T2 employs a very unusual one. That's the GU-50, an all-glass military VHF output pentode, copied from the Wehrmacht LS50 tube. Initially purposed for aviation, it has a very robust design, and uses a special base: one that is loctal-like but noticeably bigger:



Since driving the horizontal sweep of a television feels like ‘a rest’ for such a 'hardy warrior’, the tube tends to work forever there, unlike the usual 6L6 clones that often become weak in a few years.
By the way, picking up the design was considered worthwhile, and soon a couple of newly-designed tubes in the same envelope were launched:

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Last edited by Gleb; 04-25-2017 at 06:18 AM.
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  #37  
Old 04-25-2017, 01:12 AM
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The picture tube looks like a prewar bulb-shaped one, since it really is a reworked prewar-type CRT:



In the late 30s-early 40s, the line of 7", 9", and 12" television CRTs with magnetic deflection and focusing was developed and ready for mass production. A few televisions were introduced before the war as well, ending up in 1941 with the 7" 17TN-3 set, which was advanced enough for a prewar TV but still inexpensive:


[rw6ase.narod.ru]

and the bigger 23TN-4 tabletop with a 9" picture tube. And, then came the war…


[AP photo]

As you can guess, a significant part of the industry was ruined by the war so production chains and co-operations were broken. That's why the Moskvich-T1 known as the first postwar work in television, seems to trail behind even some prewar sets - it was just composed from some available components on some undamaged equipment by some surviving designers:


[rw6ase.narod.ru]

However, by 1946 the industry was recovering pretty quickly, thus the need for CRTs was increasing. Since the prewar picture tubes were considered good enough, the CRT manufacturers reasonably decided not to 'reinvent the wheel' and just re-engaged their production, along with some improvements.

So, let's end that little historical excursus and get back to the TV. The main chassis features the way the picture tube is secured. The bell of the CRT is pulled up by a spring-loaded rim to the back side of the strong plastic frame, while the neck is held by the deflection yoke mounted on the chassis:



The frame itself, covered by the safety glass from the front,



is bolted to the front of the chassis, thus forming a solid and integral ‘main chassis unit’ that can be pulled out of the cabinet and securely played/serviced/repaired. Also the picture tube attached to the frame can be easily removed from the front of the cabinet by sliding the decorative screen bezel aside and unscrewing the plastic frame from the chassis.

The assembling is obviously neat and most of the wires and cables are gathered in bundles:



Some components are wired to the distribution rails which are made of thick tinned copper wire threaded through the isolating phenolic stands.
The porcelain socket of the local oscillator tube is mounted on the antivibration suspension:



The power supply chassis sits on the floor of the cabinet next to the main chassis; a thick harness with a tough 22-pin connector is used for their interconnection. In fact, the power chassis gathers two independent power supplies, for the audio and video sections, accordingly:



The bigger transformer powers up the video section, along with the rectifier that uses two 5Z4 tubes in parallel, and the massive filter choke mounted in the middle of the chassis. The section turns on and off automatically while switching between television and radio modes. The smaller transformer and the single rectifier tube that sits right on its top cover, are responsible for the audio section of the TV and the radio receiver. The field coil of the speaker is used as a filter choke for that section. The rest of the power circuitry is collected on the power chassis as well, including all the filter capacitors on the top of the chassis, and a set of the ceramic bleeder resistors underneath:



Some of the resistors are tapped to provide all the needed negative voltages. All of that explains such a big number of pins/wires in the interchassis connection.

The performance of a functional and properly-aligned Leningrad-T2 is impressive due to the declared relatively high grade of the set for the time, and mostly due to the pretty high-definition 625-line standard:



And some video as well (clickable):

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Last edited by Gleb; 01-09-2019 at 05:12 AM.
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  #38  
Old 04-25-2017, 01:37 AM
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Thank you, Gleb, for that informative discussion and the beautiful photos. An impressive television in more than one sense.

The Leningrad's tidy under-chassis layout is a real contrast to the TV that I'm currently restoring: a 1949 Emerson from the USA. The Emerson has some of the sloppiest layout and construction that I've seen, with long, unbundled "lazy man" leads trailing all over the underside and obscuring other components. Cheap to build and annoying to service!

Phil Nelson
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http://antiqueradio.org/index.html

Last edited by Phil Nelson; 04-25-2017 at 11:55 AM.
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  #39  
Old 04-25-2017, 07:37 AM
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M3-SRT8 M3-SRT8 is offline
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Beautiful point to point wiring. Were these TVs made in Russia or East Germany?
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  #40  
Old 04-25-2017, 07:59 AM
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Quote:
Originally Posted by M3-SRT8 View Post
Were these TVs made in Russia or East Germany?
In both countries actually, but in Russia the production had discontinued earlier, in favor of some new 12" tabletops. I described the production issues in the beginning of the post.
The originating designer and manufacturer, the Kazitsky plant, was known for its impressive assembling approach:



That's their 12" tabletop TV from 1953 that I mentioned.
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Last edited by Gleb; 04-26-2017 at 04:28 PM.
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  #41  
Old 04-25-2017, 08:12 AM
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M3-SRT8 M3-SRT8 is offline
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Quote:
Originally Posted by Gleb View Post
In both countries actually, but in Russia the prodiction was discontinued earlier, in favour of some new 12" tabletops. I described the production issues in the beginning of the post.
Any indications where yours was finally assembled ?
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  #42  
Old 04-25-2017, 08:26 AM
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Quote:
Originally Posted by M3-SRT8 View Post
Any indications where yours was finally assembled?
Mine is an early German one.
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  #43  
Old 04-25-2017, 08:33 AM
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Quite impressive craftsmanship. It has the feel of a Dumont set made close to mil spec, with pre-war looking parts.
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  #44  
Old 04-25-2017, 08:41 AM
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M3-SRT8 M3-SRT8 is offline
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Originally Posted by vts1134 View Post
Not immediately. This set is very original and quite unique in this country. It's on my "it doesn't have to work" list. Someday when my kids move out and I don't have anything to do I may start restoring sets on that list. For now I'm content with some sets that work and some sets that don't.
Just rereading your entire thread.

I would leave this particular set alone. No electronic restoration.

How could you? ANY restorative work is going to leave signs, and this set should be set aside and regarded as a particularly outstanding example of Commie craftsmanship.

Sorry. Couldn't resist including one anti bolshevik barb.

Last edited by M3-SRT8; 04-25-2017 at 08:50 AM.
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  #45  
Old 04-25-2017, 08:46 AM
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I don't see any wax paper caps here. Are they all micas, discs and ceramics?
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