Mullard 12-inch Picture Tubes
Type MW31-16 with Clear Glass Face
Type MW31-74 with Grey Glass Face
Direct viewing television picture tubes with 12-inch diameter screen and incorporating an ion trap.
NOTE (applies to series operation only) - The surge heater voltage must not exceed 9.5V (r.m.s.) when the supply is switched on. When used in a series heater chain a current limiting device may be necessary in the circuit to ensure that this voltage is not exceeded.
EXTERNAL CONDUCTIVE COATING
These tubes have an external conductive coating, the capacitance of this to the final anode (900uuF) may be used to provide smoothing for the E.H.T. supply.
A space 30mm along the neck of the tube from the edge of the base should be kept clear for the ion-trap magnet. A clamp of non-magnetic material not more than 10mm wide may be placed between this space and the focus coil.
|Ion-trap magnetic field intensity :||52 to 60 G|
Any, except vertical with screen downwards and the axis of the tube making an angle of less than 50 degrees with the vertical.
TYPICAL OPERATING CONDITIONS
|*Vg||-32 to -71||-44 to -99||V|
LIMITING VALUES (Design centre ratings)
| Vh-k max. (heater negative)||200||V|
| Focusing ampere-
|*||The D.C. value of the grid bias must not be allowed to become positive with respect to the cathode, except during the period immediately after switching off the receiver, when it may be allowed, to rise to +1V. The maximum positive grid excursion may reach 2V and at this voltage the grid current may be expected to be approximately 2mA|
|**||The product of Vg2 and It (average value for the whole screen) must not exceed 6W.|
|||In order to avoid excessive hum the A.C. component of Vh-k should be as low as possible (<20Vr.m.s.).|
|||During a warming-up period not exceeding 45 secs.|
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17th September 2001