1960 Prima 1 Valve TV

[Don Lindsly]

I suspect this schematic is a joke or a classroom exercise. There are several things "wrong with this picture". 1. The antenna circuit feeds the grid of the video amp. Where's the detector? No RF or IF gain at all says there's just not enough dBs to get anything done. The video output taken off the screen grid. The horizontal oscillator/output would be modulated by the video and the reverse.

Don't take it too seriously. It is not intended to work.

Don

[Chad Hauris]

This could have been used in a city where there was perhaps one government owned TV station. The selectivity would be in the antenna coil tuned for the one station. If you had say 500 kw of visual power from the transmitter, and were a few miles away, I'm sure you could get an O.K. signal with this little amplification. It could be perhaps an anode detector like is used in old TRF radio sets...no seperate diode is needed.

[daro]

Originally Posted by Chad Hauris

This could have been used in a city where there was perhaps one government owned TV station. The selectivity would be in the antenna coil tuned for the one station. If you had say 500 kw of visual power from the transmitter, and were a few miles away, I'm sure you could get an O.K. signal with this little amplification. It could be perhaps an anode detector like is used in old TRF radio sets...no seperate diode is needed.

This TV is the Eastern Bloc equivalent to all those 2 & 3 valve TRF radios that were made in Nazi Germany before the WWII.

The CRT is more then likley a 5 inch judging by the EHT voltage, The set is more then likley made & sold very cheapley by the state as tool for spreading properganda by the state as was those radios in Nazi Germany.

I am trying to find out more info on this simple TV set on the net, But I have had no success so far..

Perhaps Telecolor 3007 might know somthing about these.

The website I d/l the circut was in Poland.

[wa2ise]

Originally Posted by Don Lindsly

I suspect this schematic is a joke or a classroom exercise. There are several things "wrong with this picture". 1. The antenna circuit feeds the grid of the video amp. Where's the detector? No RF or IF gain at all says there's just not enough dBs to get anything done. The video output taken off the screen grid. The horizontal oscillator/output would be modulated by the video and the reverse.

The cathode and G1 of the first tube looks like a Hartley local oscillator of the sort found in AA5 AM tube radios. Maybe the oscillation is partly locked on the signal's carrier and creates a synchronous detector? As for the horizontal oscillator, usually max RF on the carrier happens on sync tip. Which would be a big pulse when detected. Maybe that could "tickle" the feedback circuit between G4 and the plate of the tube? And create the horizontal deflection waveform and high voltage? But where does the vertical come from? Oh wait, it just assumes the vertical is the same frequency as the powerline, and you have to twiddle the hold knob to phase it in.

The sound is fairly straightforward, just an FM ratio detector detecting the FM subcarreir off the video.