[Milsurplus] SCR-522 in 12V yeep

[Mike Morrow]

>Don't have the SCR # but '522 used in Jeeps w. PE-98(?) that
>generated B+ AND xtra 14VDC to series w. Jeep battery


Hi Marty,

The 14 vdc version of the SCR-522-A is the SCR-542-A, and the only
difference between the two sets is that the SCR-542 uses the PE-98 you
mention rather than the 28 vdc PE-94.  The PE units are rather interesting.

The receiver-transmitter (BC-625, 625) uses 14 vdc for filament and control
circuits, regardless of whether it is used in a 14 or 28 vdc installation.
The PE-94 or 98 has three outputs:  +300 vdc, -150vdc, and **14 vdc **.
What's really unusual with these sets is that a separate rotor winding on
the dynamotor generates the LV needed by the RT set.   The LV does NOT come
directly from the battery, even when the RT unit is used in a 14 vdc
vehicle.  The dynamotor has a regulating field controlled with a carbon-pile
regulator sensing the LV output to the RT.  Though there's loss of
efficiency, obviously the benefit from having the LV generated by the
dynamotor is that even the LV will be regulated over a wide range of PE
input voltage.  (I suppose when you have a set that consumes more than 300
watts to generate less than 10 watts RF, efficiency isn't a driving
parameter anyway.)

To me, the PE-94 and 98 are the most technically remarkable power units
found on WWII gear (three field windings, four rotor windings).  They must
have been expensive compared to the simpler designs used on almost
everything else.  I wonder if it the design was British inspired.

73,
Mike / KK5F