[MRCA] R105D / R105M Power

[wf2u at starband.net]

Breck,

That's a good solution as well.
I didn't find the simple diaode center tap as unstable and it works well
for me, so I didn't bother to design anything more elaborate.
The 12 V to 5 V regulator is a nice idea, especially for field operations
as you don't have to bother with 2 power supplies for the high power
(vehicular) mode. I use mine at home so 2 power supplies is no big deal...

73, Meir WF2U
Landrum, SC


> 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
>
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