[MRCA] R105D / R105M Power

[B. Smith]

I use two pass transistors to create a "phantom" centertap to provide the 
voltages. As I was not satisfed with the diode regulation.  I also built a 
12 volt to 5 volt regulator to provide power in the field at the MRCA meets.

Many thanks to N3FRQ for his suggestion.

Photos at "
http://solo11.abac.com/zorroab1/R104Mpower/R104Mpower.htm


73 breck k4che
"Crystal-controlled, weak, and on AM is no way to go through life"





73, Meir WF2U said:


| | As to the substitute for the wet cell batteries originally used, the way
| to easily power up the radios requiring +/- 2.8V is from a 5 V power
| supply, through a simple an artificial center tap consisting of a couple
| of diodes and resistors. The circuit is not tricky at all and works great
| with nothing to adjust.
| I can either send the circuit or point to a web site where the circuit is
| presented (I'm at work now so I can do it later when I get home).
| I use this setup to power up my Russian R-104M HF transceiver (all tubes,
| 20 W output)  and the same circuit will work as well with low power sets.
| /mrca