ADDING SCREEN-GRID VALVE TO SHORT-WAVE ADAPTER

Radio Record, Volume II, Issue 3, 3 August 1928, Page 62

ADDING SCREEN-GRID VALVE TO SHORT-WAVE ADAPTER

N reply to a number of inquiries, it may be stated that the most effective way of applying the screen-grid yulye to the Record short-wave adapter, or to any other wit] the same circuit, is to make up the screen-grid R.F. stage as deseribed ‘on June 29. This section is then to be fastened to the left-hand side of the wdapter by means of inch strips of wood ‘screwed underneath, raaking one complete unit. It should be specially noted that the same pole of the A battery must- be earthed as is done in the broadcast receiver itself, which is usually the negative, whilst the diagram of the adapter shows A positive earthed: as in the full receiver, which is the usual practice. Alterations in the adapter of posttion of grid-leak, ‘and connections for 90 volts B and additic. of .002 fixed condenser are explained in the article. The secondary coil used in_ the screen-grid stage must be a duplicate of the one in the detector stage. The aerial coil and operating spindle is removed from-the detector stage to the screen-grid stage. Both sereen-grid snd detector stacy shoulG be separately sereened With? 28's copper. including the pack of panel, to secure best results. For the detector stage the copper sereea can be screwed underneath to.save — lifting components off the beard, —