Transformer mod. for dial lamps now fitted.
The donor transformer came from a plug-in 'wall wart': its label stated 14v. @ 400 mA. I wired it to two 6.3v 0.3 amp. bulbs connected in series and obtained 12v. across the pair. The transformer needed a clamping bracket so that the transformer could be secured to the chassis: that was easily accomplished by using a scrap piece of aluminium and simply cutting and bending it to the required size and shape. I managed to squeeze the transformer + clamp behind the IF valve and the two IFTs - as you can see in the photo. The resulting dial illumination is excellent - as can also be seen from the photo.
[attachment=8088] [attachment=8089]
With the removal of the old 3.15v. bulbs (which were O/C anyway), the dial bulbs shunt resistor of 75Ω was replaced by 27Ω to maintain the correct current of 100 mA through the heater chain.
Thank you, David, for bringing this mod. to my attention.
Al. / May 31st, 2013 //
The donor transformer came from a plug-in 'wall wart': its label stated 14v. @ 400 mA. I wired it to two 6.3v 0.3 amp. bulbs connected in series and obtained 12v. across the pair. The transformer needed a clamping bracket so that the transformer could be secured to the chassis: that was easily accomplished by using a scrap piece of aluminium and simply cutting and bending it to the required size and shape. I managed to squeeze the transformer + clamp behind the IF valve and the two IFTs - as you can see in the photo. The resulting dial illumination is excellent - as can also be seen from the photo.
[attachment=8088] [attachment=8089]
With the removal of the old 3.15v. bulbs (which were O/C anyway), the dial bulbs shunt resistor of 75Ω was replaced by 27Ω to maintain the correct current of 100 mA through the heater chain.
Thank you, David, for bringing this mod. to my attention.
Al. / May 31st, 2013 //
