29-10-2016, 07:56 PM
(This post was last modified: 29-10-2016, 07:58 PM by Geordie McBoyne.)
Easy fix, the receiver HT supply rectifier had an OC filament. The original Cossor valve was a type 4/100BU, the nearest Mullard equivalent is the FW4-500. Didn't have either of these in stock so an Osram U14 will be used as a temporary measure until the correct valve is found.
The set now displays a rather dim picture, what can anyone expect from an eighty year old CRT? Note the compression at the left of the picture. Frame and line holds are excellent, the picture remains locked over a wide range of rotation the hold controls.
Other details: the horizontal picture shift has two controls. The sound output valve is a Cossor type 2P, a two volt filament directly heated triode. The TV receiver is a superhet, the IFs have not been determined yet. Like the contemporary GEC TVs the Cossor also has a very low vision intermediate frequency and for that reason a full wave video demodulator is employed, a Cossor DDL4 low capacitance double diode is used.
The set is far from perfect but it will ready for the 2nd of November.
Geordie McBoyne.
The set now displays a rather dim picture, what can anyone expect from an eighty year old CRT? Note the compression at the left of the picture. Frame and line holds are excellent, the picture remains locked over a wide range of rotation the hold controls.
Other details: the horizontal picture shift has two controls. The sound output valve is a Cossor type 2P, a two volt filament directly heated triode. The TV receiver is a superhet, the IFs have not been determined yet. Like the contemporary GEC TVs the Cossor also has a very low vision intermediate frequency and for that reason a full wave video demodulator is employed, a Cossor DDL4 low capacitance double diode is used.
The set is far from perfect but it will ready for the 2nd of November.
Geordie McBoyne.
