23-04-2017, 06:33 PM
(This post was last modified: 23-04-2017, 06:35 PM by Geordie McBoyne.)
Further examination of this receiver reveals that the RF amplifier is not an EF50 but in is fact an EF54, the giveaway is how the valveholder wired. In the EF54 the anode is connected to pin 2 and the screen grid to pin 3. The cathode is connected to no less than four pins, 4, 5, 7 and 8. The developer of this valve (Philips in Holland or Mullard in the UK?) made sure that the cathode inductances were reduced to the minimum. Considering the choice of this valve as the RF amplifier it would seem the guy who did the modifications to the 1804 really knew what he was doing after all.
Info about the EF54: http://www.r-type.org/exhib/aaa1093.htm
To reduce the noise factor the EF54 employs the aligned grids technique. This must be the only known application of this valve in a television receiver.
Geordie McBoyne.
Info about the EF54: http://www.r-type.org/exhib/aaa1093.htm
To reduce the noise factor the EF54 employs the aligned grids technique. This must be the only known application of this valve in a television receiver.
Geordie McBoyne.
