Quote:
|
Originally Posted by Sandy G
Damn ...!! Wish I could read German...<grin>
|
I wish I could be a professional translater:
I am 52 and have started in the 1960s to be interested in radiocommunication. At that time our neighbor was a radio ham and then I have also started with it. In the club station GST were many members who worked in Berlin WF. End of the 60th in the WF the rumor arose that the preproduction of a further development of the round 21" / 70° color picture tube, the 17" / 70° rectangular colour picture tube should be scrapped because the COMECON (a council for mutual economic aid, a "supra-national" economic plan organization of the former Eastern Bloc) had decided that the entire color picture tube production for the Eastern Bloc states will be executed in the USSR on the basis of a RCA licence for a 21" / 90 ° rectanglular color picture tube. The color pitcure tube development in the G.D.R. should be stopped.
This was --of course-- a reason for some workers in the WF, this one and single color picture tube of the G.D.R. to rescue. And so 4 - 6 crts were gathered, which were smuggled in a cloak-and-dagger operation out of the WF. The development of the crt was so far that even some tubes had the labels B43G4C.
But what to do with a naked color picture tube without any supplies, without yoke, convergence units, no purity magnets--nothing more than the simple color picture tube? The yokes of the b/w tv sets were not suitable, a color picture tube has three guns and the neck was much thicker (40 millimeter as far as I can remember). At first some old plans for wiring deflection coils were found in old books from the beginning of television technique. The ferrite core of the yoke was built from old ferrite cores of b/w deflection yokes, which was milled and filled in suitable forms and glued with the wellknown "Duosan" glue. After some weeks of drying and airing the ferrite core was really dry and solid. The wiring of the horizontal deflection was manufactored as a saddle coil and the coil for vertical deflection was simply wired around the ferrite core.
For the convergence unit a construction on a plastic carrier with pieces of AM antenna ferrite with corresponding coils was built for dynamic convergence with small revolvable magnets. Also some magneticable brass rings with suitable diameter someone had get for purity adjustments. These all parts were assembled and fitted on a PVC tube--usually used for the john-- as the yoke for the B43G4C.
Due to the fact that the B43G4C was a 17" 70 degree picture tube, it was self-evident, to insert the picture tube into an older b/w tv housing which had already a 17" crt bezel. I know that one of us "upgraded" an old "Weißensee" b/w tv set to a color tv set. For myself I had a tv set housing of a much older brand, but I can't remember the brand.
The entire schematics for the color tv set were from any Western journal, and as far as it was possible, the b/w circuits were used. The IF and tuner stages were taken from a b/w tv set, and the vertical deflection units also. For the horizontal deflection and high voltage stages, one had to use other ways, because the 17" color picture tube needed much more power. The special horizontal output tubes from the western countries were not available, and so two separated horizontal stages were built out of b/w horizontal stages. One only for the deflection and the other one only for high voltage. This had the advantage that a problematic due to X-rays shunt regulator was not necessary.
The PAL decoder (SECAM was not already introduced) was also assembled full solid state according to a Western journal. The greatest problem was to get the color subcarrier crystal with 4.43 MHz. They used for e.g. old quartzes from russion walkie-talkies and grind them until they reached the correct frequency values. The neccesary PAL delay line was no problem. This was produced at the WF for export. Some more problematic was the Y delay line for 1 microsecond. But without need the set would work properly without it. Brightness and color were not absolutely synchronous.