[Milsurplus] BC-230 direct to 50 ohms

[Cletus W Whitaker]

de WB2CPN South Central Pennsylvania   2003.03.19

 From late 1945 through 1949, prior to and during the "Berlin
Airlift", I used BC-191's as Low Frequency Homing Beacons,
and one was used for ham radio, mostly 40 meters.  There
were a few different models of power supplies.  The very
small ones, (18" X 18" X 18" or less), were totaly unreliable.
They got too hot. But, understand that the BC-191 was
running full power with 80% tone modulation, which is
putting some stress on the power supply.  (We arranged
a 2" pipe with some holes in it along the top of the tube
compartment of the BC-191 and used a 10" squirel-cage fan.)
The one model of power supply that held up best was a very
large one that used 4" round globe rectifiers.  These tubes
were diodes in a linear arrangement, not coaxial.  The plate
was a little round wafer shaped piece of carbon which
was about 3/4" up from the filiment/cathode assembly.
There wasn't much mercury vapor in these tubes like an 866
would have.   There were really two rectifiers; the BC-191
tubes and control circuits used a DC source.  A unique
thing about the BC-191 was the large resistors which were
switched in and out by the transmitting keying relay.  The
idea was to maintain the same filiment voltage on the tubes
when the key was down as well as key up.    73  Clete