Babcock Preselector model P2A DX'er overview
Regenerative PreselectorAuthor: Edgardo Castro Bruse
San Salvador, September 5, 2019
This preselector was given to me by my Mentor Dr. Manuel Cader in 1963. It has been in operation since 1963 until present times. I found no information on this preselector, so I want to share what I have done.
I made the diagram directly from the chassis. The nominal values of resistances in the circuit are all within tolerance, except the 390 ohm/2 watt resistance, which measured 550 ohms. Since the preselector works real well, as it is, I did not change it.
Condensers C1, C2, C3, and C4 were not measured, so, I wrote in the diagram values that I considered appropriate.
All voltages were measured in actual operation of the P2A DX’er at 17.05 Mc. At present my Power Supply produces: B+ 160 VDC and 6.3 VAC. The actual current consumption is only 20 ma. Including the drain current of the VR150.!! Over the years I have used voltages B+ from 160 up to 300 V. To do this I have changed the 350 ohm/2watt resistance to the correct value for the VR150 to work properly.
I do hope you enjoy the P2A DX’er as I do.